Merge branch 'akpm' (patches from Andrew)

Merge more updates from Andrew Morton:
"147 patches, based on 7d2a07b769330c34b4deabeed939325c77a7ec2f.

Subsystems affected by this patch series: mm (memory-hotplug, rmap,
ioremap, highmem, cleanups, secretmem, kfence, damon, and vmscan),
alpha, percpu, procfs, misc, core-kernel, MAINTAINERS, lib,
checkpatch, epoll, init, nilfs2, coredump, fork, pids, criu, kconfig,
selftests, ipc, and scripts"

* emailed patches from Andrew Morton <[e-mail]>: (94 commits)
scripts: check_extable: fix typo in user error message
mm/workingset: correct kernel-doc notations
ipc: replace costly bailout check in sysvipc_find_ipc()
selftests/memfd: remove unused variable
Kconfig.debug: drop selecting non-existing HARDLOCKUP_DETECTOR_ARCH
configs: remove the obsolete CONFIG_INPUT_POLLDEV
prctl: allow to setup brk for et_dyn executables
pid: cleanup the stale comment mentioning pidmap_init().
kernel/fork.c: unexport get_{mm,task}_exe_file
coredump: fix memleak in dump_vma_snapshot()
fs/coredump.c: log if a core dump is aborted due to changed file permissions
nilfs2: use refcount_dec_and_lock() to fix potential UAF
nilfs2: fix memory leak in nilfs_sysfs_delete_snapshot_group
nilfs2: fix memory leak in nilfs_sysfs_create_snapshot_group
nilfs2: fix memory leak in nilfs_sysfs_delete_##name##_group
nilfs2: fix memory leak in nilfs_sysfs_create_##name##_group
nilfs2: fix NULL pointer in nilfs_##name##_attr_release
nilfs2: fix memory leak in nilfs_sysfs_create_device_group
trap: cleanup trap_init()
init: move usermodehelper_enable() to populate_rootfs()
...

Documentation/admin-guide/mm/damon/index.rst

···
+.. SPDX-License-Identifier: GPL-2.0
+
+========================
+Monitoring Data Accesses
+========================
+
+:doc:`DAMON </vm/damon/index>` allows light-weight data access monitoring.
+Using DAMON, users can analyze the memory access patterns of their systems and
+optimize those.
+
+.. toctree::
+   :maxdepth: 2
+
+   start
+   usage

Documentation/admin-guide/mm/damon/start.rst

···
+.. SPDX-License-Identifier: GPL-2.0
+
+===============
+Getting Started
+===============
+
+This document briefly describes how you can use DAMON by demonstrating its
+default user space tool.  Please note that this document describes only a part
+of its features for brevity.  Please refer to :doc:`usage` for more details.
+
+
+TL; DR
+======
+
+Follow the commands below to monitor and visualize the memory access pattern of
+your workload. ::
+
+    # # build the kernel with CONFIG_DAMON_*=y, install it, and reboot
+    # mount -t debugfs none /sys/kernel/debug/
+    # git clone https://github.com/awslabs/damo
+    # ./damo/damo record $(pidof <your workload>)
+    # ./damo/damo report heat --plot_ascii
+
+The final command draws the access heatmap of ``<your workload>``.  The heatmap
+shows which memory region (x-axis) is accessed when (y-axis) and how frequently
+(number; the higher the more accesses have been observed). ::
+
+    111111111111111111111111111111111111111111111111111111110000
+    111121111111111111111111111111211111111111111111111111110000
+    000000000000000000000000000000000000000000000000001555552000
+    000000000000000000000000000000000000000000000222223555552000
+    000000000000000000000000000000000000000011111677775000000000
+    000000000000000000000000000000000000000488888000000000000000
+    000000000000000000000000000000000177888400000000000000000000
+    000000000000000000000000000046666522222100000000000000000000
+    000000000000000000000014444344444300000000000000000000000000
+    000000000000000002222245555510000000000000000000000000000000
+    # access_frequency:  0  1  2  3  4  5  6  7  8  9
+    # x-axis: space (140286319947776-140286426374096: 101.496 MiB)
+    # y-axis: time (605442256436361-605479951866441: 37.695430s)
+    # resolution: 60x10 (1.692 MiB and 3.770s for each character)
+
+
+Prerequisites
+=============
+
+Kernel
+------
+
+You should first ensure your system is running on a kernel built with
+``CONFIG_DAMON_*=y``.
+
+
+User Space Tool
+---------------
+
+For the demonstration, we will use the default user space tool for DAMON,
+called DAMON Operator (DAMO).  It is available at
+https://github.com/awslabs/damo.  The examples below assume that ``damo`` is on
+your ``$PATH``.  It's not mandatory, though.
+
+Because DAMO is using the debugfs interface (refer to :doc:`usage` for the
+detail) of DAMON, you should ensure debugfs is mounted.  Mount it manually as
+below::
+
+    # mount -t debugfs none /sys/kernel/debug/
+
+or append the following line to your ``/etc/fstab`` file so that your system
+can automatically mount debugfs upon booting::
+
+    debugfs /sys/kernel/debug debugfs defaults 0 0
+
+
+Recording Data Access Patterns
+==============================
+
+The commands below record the memory access patterns of a program and save the
+monitoring results to a file. ::
+
+    $ git clone https://github.com/sjp38/masim
+    $ cd masim; make; ./masim ./configs/zigzag.cfg &
+    $ sudo damo record -o damon.data $(pidof masim)
+
+The first two lines of the commands download an artificial memory access
+generator program and run it in the background.  The generator will repeatedly
+access two 100 MiB sized memory regions one by one.  You can substitute this
+with your real workload.  The last line asks ``damo`` to record the access
+pattern in the ``damon.data`` file.
+
+
+Visualizing Recorded Patterns
+=============================
+
+The following three commands visualize the recorded access patterns and save
+the results as separate image files. ::
+
+    $ damo report heats --heatmap access_pattern_heatmap.png
+    $ damo report wss --range 0 101 1 --plot wss_dist.png
+    $ damo report wss --range 0 101 1 --sortby time --plot wss_chron_change.png
+
+- ``access_pattern_heatmap.png`` will visualize the data access pattern in a
+  heatmap, showing which memory region (y-axis) got accessed when (x-axis)
+  and how frequently (color).
+- ``wss_dist.png`` will show the distribution of the working set size.
+- ``wss_chron_change.png`` will show how the working set size has
+  chronologically changed.
+
+You can view the visualizations of this example workload at [1]_.
+Visualizations of other realistic workloads are available at [2]_ [3]_ [4]_.
+
+.. [1] https://damonitor.github.io/doc/html/v17/admin-guide/mm/damon/start.html#visualizing-recorded-patterns
+.. [2] https://damonitor.github.io/test/result/visual/latest/rec.heatmap.1.png.html
+.. [3] https://damonitor.github.io/test/result/visual/latest/rec.wss_sz.png.html
+.. [4] https://damonitor.github.io/test/result/visual/latest/rec.wss_time.png.html

Documentation/admin-guide/mm/damon/usage.rst

···
+.. SPDX-License-Identifier: GPL-2.0
+
+===============
+Detailed Usages
+===============
+
+DAMON provides below three interfaces for different users.
+
+- *DAMON user space tool.*
+  This is for privileged people such as system administrators who want a
+  just-working human-friendly interface.  Using this, users can use the DAMON’s
+  major features in a human-friendly way.  It may not be highly tuned for
+  special cases, though.  It supports only virtual address spaces monitoring.
+- *debugfs interface.*
+  This is for privileged user space programmers who want more optimized use of
+  DAMON.  Using this, users can use DAMON’s major features by reading
+  from and writing to special debugfs files.  Therefore, you can write and use
+  your personalized DAMON debugfs wrapper programs that reads/writes the
+  debugfs files instead of you.  The DAMON user space tool is also a reference
+  implementation of such programs.  It supports only virtual address spaces
+  monitoring.
+- *Kernel Space Programming Interface.*
+  This is for kernel space programmers.  Using this, users can utilize every
+  feature of DAMON most flexibly and efficiently by writing kernel space
+  DAMON application programs for you.  You can even extend DAMON for various
+  address spaces.
+
+Nevertheless, you could write your own user space tool using the debugfs
+interface.  A reference implementation is available at
+https://github.com/awslabs/damo.  If you are a kernel programmer, you could
+refer to :doc:`/vm/damon/api` for the kernel space programming interface.  For
+the reason, this document describes only the debugfs interface
+
+debugfs Interface
+=================
+
+DAMON exports three files, ``attrs``, ``target_ids``, and ``monitor_on`` under
+its debugfs directory, ``<debugfs>/damon/``.
+
+
+Attributes
+----------
+
+Users can get and set the ``sampling interval``, ``aggregation interval``,
+``regions update interval``, and min/max number of monitoring target regions by
+reading from and writing to the ``attrs`` file.  To know about the monitoring
+attributes in detail, please refer to the :doc:`/vm/damon/design`.  For
+example, below commands set those values to 5 ms, 100 ms, 1,000 ms, 10 and
+1000, and then check it again::
+
+    # cd <debugfs>/damon
+    # echo 5000 100000 1000000 10 1000 > attrs
+    # cat attrs
+    5000 100000 1000000 10 1000
+
+
+Target IDs
+----------
+
+Some types of address spaces supports multiple monitoring target.  For example,
+the virtual memory address spaces monitoring can have multiple processes as the
+monitoring targets.  Users can set the targets by writing relevant id values of
+the targets to, and get the ids of the current targets by reading from the
+``target_ids`` file.  In case of the virtual address spaces monitoring, the
+values should be pids of the monitoring target processes.  For example, below
+commands set processes having pids 42 and 4242 as the monitoring targets and
+check it again::
+
+    # cd <debugfs>/damon
+    # echo 42 4242 > target_ids
+    # cat target_ids
+    42 4242
+
+Note that setting the target ids doesn't start the monitoring.
+
+
+Turning On/Off
+--------------
+
+Setting the files as described above doesn't incur effect unless you explicitly
+start the monitoring.  You can start, stop, and check the current status of the
+monitoring by writing to and reading from the ``monitor_on`` file.  Writing
+``on`` to the file starts the monitoring of the targets with the attributes.
+Writing ``off`` to the file stops those.  DAMON also stops if every target
+process is terminated.  Below example commands turn on, off, and check the
+status of DAMON::
+
+    # cd <debugfs>/damon
+    # echo on > monitor_on
+    # echo off > monitor_on
+    # cat monitor_on
+    off
+
+Please note that you cannot write to the above-mentioned debugfs files while
+the monitoring is turned on.  If you write to the files while DAMON is running,
+an error code such as ``-EBUSY`` will be returned.
+
+
+Tracepoint for Monitoring Results
+=================================
+
+DAMON provides the monitoring results via a tracepoint,
+``damon:damon_aggregated``.  While the monitoring is turned on, you could
+record the tracepoint events and show results using tracepoint supporting tools
+like ``perf``.  For example::
+
+    # echo on > monitor_on
+    # perf record -e damon:damon_aggregated &
+    # sleep 5
+    # kill 9 $(pidof perf)
+    # echo off > monitor_on
+    # perf script

Documentation/admin-guide/mm/index.rst

···
 
    concepts
    cma_debugfs
+   damon/index
    hugetlbpage
    idle_page_tracking
    ksm

Documentation/admin-guide/mm/memory-hotplug.rst

···
 .. _admin_guide_memory_hotplug:
 
-==============
-Memory Hotplug
-==============
+==================
+Memory Hot(Un)Plug
+==================
 
-:Created:							Jul 28 2007
-:Updated: Add some details about locking internals:		Aug 20 2018
-
-This document is about memory hotplug including how-to-use and current status.
-Because Memory Hotplug is still under development, contents of this text will
-be changed often.
+This document describes generic Linux support for memory hot(un)plug with
+a focus on System RAM, including ZONE_MOVABLE support.
 
 .. contents:: :local:
-
-.. note::
-
-    (1) x86_64's has special implementation for memory hotplug.
-        This text does not describe it.
-    (2) This text assumes that sysfs is mounted at ``/sys``.
-
 
 Introduction
 ============
 
-Purpose of memory hotplug
--------------------------
+Memory hot(un)plug allows for increasing and decreasing the size of physical
+memory available to a machine at runtime. In the simplest case, it consists of
+physically plugging or unplugging a DIMM at runtime, coordinated with the
+operating system.
 
-Memory Hotplug allows users to increase/decrease the amount of memory.
-Generally, there are two purposes.
+Memory hot(un)plug is used for various purposes:
 
-(A) For changing the amount of memory.
-    This is to allow a feature like capacity on demand.
-(B) For installing/removing DIMMs or NUMA-nodes physically.
-    This is to exchange DIMMs/NUMA-nodes, reduce power consumption, etc.
+- The physical memory available to a machine can be adjusted at runtime, up- or
+  downgrading the memory capacity. This dynamic memory resizing, sometimes
+  referred to as "capacity on demand", is frequently used with virtual machines
+  and logical partitions.
 
-(A) is required by highly virtualized environments and (B) is required by
-hardware which supports memory power management.
+- Replacing hardware, such as DIMMs or whole NUMA nodes, without downtime. One
+  example is replacing failing memory modules.
 
-Linux memory hotplug is designed for both purpose.
+- Reducing energy consumption either by physically unplugging memory modules or
+  by logically unplugging (parts of) memory modules from Linux.
 
-Phases of memory hotplug
-------------------------
+Further, the basic memory hot(un)plug infrastructure in Linux is nowadays also
+used to expose persistent memory, other performance-differentiated memory and
+reserved memory regions as ordinary system RAM to Linux.
 
-There are 2 phases in Memory Hotplug:
+Linux only supports memory hot(un)plug on selected 64 bit architectures, such as
+x86_64, arm64, ppc64, s390x and ia64.
 
-  1) Physical Memory Hotplug phase
-  2) Logical Memory Hotplug phase.
+Memory Hot(Un)Plug Granularity
+------------------------------
 
-The First phase is to communicate hardware/firmware and make/erase
-environment for hotplugged memory. Basically, this phase is necessary
-for the purpose (B), but this is good phase for communication between
-highly virtualized environments too.
-
-When memory is hotplugged, the kernel recognizes new memory, makes new memory
-management tables, and makes sysfs files for new memory's operation.
-
-If firmware supports notification of connection of new memory to OS,
-this phase is triggered automatically. ACPI can notify this event. If not,
-"probe" operation by system administration is used instead.
-(see :ref:`memory_hotplug_physical_mem`).
-
-Logical Memory Hotplug phase is to change memory state into
-available/unavailable for users. Amount of memory from user's view is
-changed by this phase. The kernel makes all memory in it as free pages
-when a memory range is available.
-
-In this document, this phase is described as online/offline.
-
-Logical Memory Hotplug phase is triggered by write of sysfs file by system
-administrator. For the hot-add case, it must be executed after Physical Hotplug
-phase by hand.
-(However, if you writes udev's hotplug scripts for memory hotplug, these
-phases can be execute in seamless way.)
-
-Unit of Memory online/offline operation
----------------------------------------
-
-Memory hotplug uses SPARSEMEM memory model which allows memory to be divided
-into chunks of the same size. These chunks are called "sections". The size of
-a memory section is architecture dependent. For example, power uses 16MiB, ia64
-uses 1GiB.
+Memory hot(un)plug in Linux uses the SPARSEMEM memory model, which divides the
+physical memory address space into chunks of the same size: memory sections. The
+size of a memory section is architecture dependent. For example, x86_64 uses
+128 MiB and ppc64 uses 16 MiB.
 
 Memory sections are combined into chunks referred to as "memory blocks". The
-size of a memory block is architecture dependent and represents the logical
-unit upon which memory online/offline operations are to be performed. The
-default size of a memory block is the same as memory section size unless an
-architecture specifies otherwise. (see :ref:`memory_hotplug_sysfs_files`.)
+size of a memory block is architecture dependent and corresponds to the smallest
+granularity that can be hot(un)plugged. The default size of a memory block is
+the same as memory section size, unless an architecture specifies otherwise.
 
-To determine the size (in bytes) of a memory block please read this file::
+All memory blocks have the same size.
 
-  /sys/devices/system/memory/block_size_bytes
+Phases of Memory Hotplug
+------------------------
 
-Kernel Configuration
-====================
+Memory hotplug consists of two phases:
 
-To use memory hotplug feature, kernel must be compiled with following
-config options.
+(1) Adding the memory to Linux
+(2) Onlining memory blocks
 
-- For all memory hotplug:
-    - Memory model -> Sparse Memory  (``CONFIG_SPARSEMEM``)
-    - Allow for memory hot-add       (``CONFIG_MEMORY_HOTPLUG``)
+In the first phase, metadata, such as the memory map ("memmap") and page tables
+for the direct mapping, is allocated and initialized, and memory blocks are
+created; the latter also creates sysfs files for managing newly created memory
+blocks.
 
-- To enable memory removal, the following are also necessary:
-    - Allow for memory hot remove    (``CONFIG_MEMORY_HOTREMOVE``)
-    - Page Migration                 (``CONFIG_MIGRATION``)
+In the second phase, added memory is exposed to the page allocator. After this
+phase, the memory is visible in memory statistics, such as free and total
+memory, of the system.
 
-- For ACPI memory hotplug, the following are also necessary:
-    - Memory hotplug (under ACPI Support menu) (``CONFIG_ACPI_HOTPLUG_MEMORY``)
-    - This option can be kernel module.
+Phases of Memory Hotunplug
+--------------------------
 
-- As a related configuration, if your box has a feature of NUMA-node hotplug
-  via ACPI, then this option is necessary too.
+Memory hotunplug consists of two phases:
 
-    - ACPI0004,PNP0A05 and PNP0A06 Container Driver (under ACPI Support menu)
-      (``CONFIG_ACPI_CONTAINER``).
+(1) Offlining memory blocks
+(2) Removing the memory from Linux
 
-     This option can be kernel module too.
+In the fist phase, memory is "hidden" from the page allocator again, for
+example, by migrating busy memory to other memory locations and removing all
+relevant free pages from the page allocator After this phase, the memory is no
+longer visible in memory statistics of the system.
 
+In the second phase, the memory blocks are removed and metadata is freed.
 
-.. _memory_hotplug_sysfs_files:
+Memory Hotplug Notifications
+============================
 
-sysfs files for memory hotplug
+There are various ways how Linux is notified about memory hotplug events such
+that it can start adding hotplugged memory. This description is limited to
+systems that support ACPI; mechanisms specific to other firmware interfaces or
+virtual machines are not described.
+
+ACPI Notifications
+------------------
+
+Platforms that support ACPI, such as x86_64, can support memory hotplug
+notifications via ACPI.
+
+In general, a firmware supporting memory hotplug defines a memory class object
+HID "PNP0C80". When notified about hotplug of a new memory device, the ACPI
+driver will hotplug the memory to Linux.
+
+If the firmware supports hotplug of NUMA nodes, it defines an object _HID
+"ACPI0004", "PNP0A05", or "PNP0A06". When notified about an hotplug event, all
+assigned memory devices are added to Linux by the ACPI driver.
+
+Similarly, Linux can be notified about requests to hotunplug a memory device or
+a NUMA node via ACPI. The ACPI driver will try offlining all relevant memory
+blocks, and, if successful, hotunplug the memory from Linux.
+
+Manual Probing
+--------------
+
+On some architectures, the firmware may not be able to notify the operating
+system about a memory hotplug event. Instead, the memory has to be manually
+probed from user space.
+
+The probe interface is located at::
+
+	/sys/devices/system/memory/probe
+
+Only complete memory blocks can be probed. Individual memory blocks are probed
+by providing the physical start address of the memory block::
+
+	% echo addr > /sys/devices/system/memory/probe
+
+Which results in a memory block for the range [addr, addr + memory_block_size)
+being created.
+
+.. note::
+
+  Using the probe interface is discouraged as it is easy to crash the kernel,
+  because Linux cannot validate user input; this interface might be removed in
+  the future.
+
+Onlining and Offlining Memory Blocks
+====================================
+
+After a memory block has been created, Linux has to be instructed to actually
+make use of that memory: the memory block has to be "online".
+
+Before a memory block can be removed, Linux has to stop using any memory part of
+the memory block: the memory block has to be "offlined".
+
+The Linux kernel can be configured to automatically online added memory blocks
+and drivers automatically trigger offlining of memory blocks when trying
+hotunplug of memory. Memory blocks can only be removed once offlining succeeded
+and drivers may trigger offlining of memory blocks when attempting hotunplug of
+memory.
+
+Onlining Memory Blocks Manually
+-------------------------------
+
+If auto-onlining of memory blocks isn't enabled, user-space has to manually
+trigger onlining of memory blocks. Often, udev rules are used to automate this
+task in user space.
+
+Onlining of a memory block can be triggered via::
+
+	% echo online > /sys/devices/system/memory/memoryXXX/state
+
+Or alternatively::
+
+	% echo 1 > /sys/devices/system/memory/memoryXXX/online
+
+The kernel will select the target zone automatically, usually defaulting to
+``ZONE_NORMAL`` unless ``movablecore=1`` has been specified on the kernel
+command line or if the memory block would intersect the ZONE_MOVABLE already.
+
+One can explicitly request to associate an offline memory block with
+ZONE_MOVABLE by::
+
+	% echo online_movable > /sys/devices/system/memory/memoryXXX/state
+
+Or one can explicitly request a kernel zone (usually ZONE_NORMAL) by::
+
+	% echo online_kernel > /sys/devices/system/memory/memoryXXX/state
+
+In any case, if onlining succeeds, the state of the memory block is changed to
+be "online". If it fails, the state of the memory block will remain unchanged
+and the above commands will fail.
+
+Onlining Memory Blocks Automatically
+------------------------------------
+
+The kernel can be configured to try auto-onlining of newly added memory blocks.
+If this feature is disabled, the memory blocks will stay offline until
+explicitly onlined from user space.
+
+The configured auto-online behavior can be observed via::
+
+	% cat /sys/devices/system/memory/auto_online_blocks
+
+Auto-onlining can be enabled by writing ``online``, ``online_kernel`` or
+``online_movable`` to that file, like::
+
+	% echo online > /sys/devices/system/memory/auto_online_blocks
+
+Modifying the auto-online behavior will only affect all subsequently added
+memory blocks only.
+
+.. note::
+
+  In corner cases, auto-onlining can fail. The kernel won't retry. Note that
+  auto-onlining is not expected to fail in default configurations.
+
+.. note::
+
+  DLPAR on ppc64 ignores the ``offline`` setting and will still online added
+  memory blocks; if onlining fails, memory blocks are removed again.
+
+Offlining Memory Blocks
+-----------------------
+
+In the current implementation, Linux's memory offlining will try migrating all
+movable pages off the affected memory block. As most kernel allocations, such as
+page tables, are unmovable, page migration can fail and, therefore, inhibit
+memory offlining from succeeding.
+
+Having the memory provided by memory block managed by ZONE_MOVABLE significantly
+increases memory offlining reliability; still, memory offlining can fail in
+some corner cases.
+
+Further, memory offlining might retry for a long time (or even forever), until
+aborted by the user.
+
+Offlining of a memory block can be triggered via::
+
+	% echo offline > /sys/devices/system/memory/memoryXXX/state
+
+Or alternatively::
+
+	% echo 0 > /sys/devices/system/memory/memoryXXX/online
+
+If offlining succeeds, the state of the memory block is changed to be "offline".
+If it fails, the state of the memory block will remain unchanged and the above
+commands will fail, for example, via::
+
+	bash: echo: write error: Device or resource busy
+
+or via::
+
+	bash: echo: write error: Invalid argument
+
+Observing the State of Memory Blocks
+------------------------------------
+
+The state (online/offline/going-offline) of a memory block can be observed
+either via::
+
+	% cat /sys/device/system/memory/memoryXXX/state
+
+Or alternatively (1/0) via::
+
+	% cat /sys/device/system/memory/memoryXXX/online
+
+For an online memory block, the managing zone can be observed via::
+
+	% cat /sys/device/system/memory/memoryXXX/valid_zones
+
+Configuring Memory Hot(Un)Plug
 ==============================
 
-All memory blocks have their device information in sysfs.  Each memory block
-is described under ``/sys/devices/system/memory`` as::
+There are various ways how system administrators can configure memory
+hot(un)plug and interact with memory blocks, especially, to online them.
+
+Memory Hot(Un)Plug Configuration via Sysfs
+------------------------------------------
+
+Some memory hot(un)plug properties can be configured or inspected via sysfs in::
+
+	/sys/devices/system/memory/
+
+The following files are currently defined:
+
+====================== =========================================================
+``auto_online_blocks`` read-write: set or get the default state of new memory
+		       blocks; configure auto-onlining.
+
+		       The default value depends on the
+		       CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel configuration
+		       option.
+
+		       See the ``state`` property of memory blocks for details.
+``block_size_bytes``   read-only: the size in bytes of a memory block.
+``probe``	       write-only: add (probe) selected memory blocks manually
+		       from user space by supplying the physical start address.
+
+		       Availability depends on the CONFIG_ARCH_MEMORY_PROBE
+		       kernel configuration option.
+``uevent``	       read-write: generic udev file for device subsystems.
+====================== =========================================================
+
+.. note::
+
+  When the CONFIG_MEMORY_FAILURE kernel configuration option is enabled, two
+  additional files ``hard_offline_page`` and ``soft_offline_page`` are available
+  to trigger hwpoisoning of pages, for example, for testing purposes. Note that
+  this functionality is not really related to memory hot(un)plug or actual
+  offlining of memory blocks.
+
+Memory Block Configuration via Sysfs
+------------------------------------
+
+Each memory block is represented as a memory block device that can be
+onlined or offlined. All memory blocks have their device information located in
+sysfs. Each present memory block is listed under
+``/sys/devices/system/memory`` as::
 
 	/sys/devices/system/memory/memoryXXX
 
-where XXX is the memory block id.
+where XXX is the memory block id; the number of digits is variable.
 
-For the memory block covered by the sysfs directory.  It is expected that all
-memory sections in this range are present and no memory holes exist in the
-range. Currently there is no way to determine if there is a memory hole, but
-the existence of one should not affect the hotplug capabilities of the memory
-block.
+A present memory block indicates that some memory in the range is present;
+however, a memory block might span memory holes. A memory block spanning memory
+holes cannot be offlined.
 
-For example, assume 1GiB memory block size. A device for a memory starting at
+For example, assume 1 GiB memory block size. A device for a memory starting at
 0x100000000 is ``/sys/device/system/memory/memory4``::
 
 	(0x100000000 / 1Gib = 4)
 
 This device covers address range [0x100000000 ... 0x140000000)
 
-Under each memory block, you can see 5 files:
-
-- ``/sys/devices/system/memory/memoryXXX/phys_index``
-- ``/sys/devices/system/memory/memoryXXX/phys_device``
-- ``/sys/devices/system/memory/memoryXXX/state``
-- ``/sys/devices/system/memory/memoryXXX/removable``
-- ``/sys/devices/system/memory/memoryXXX/valid_zones``
+The following files are currently defined:
 
 =================== ============================================================
-``phys_index``      read-only and contains memory block id, same as XXX.
-``state``           read-write
-
-                    - at read:  contains online/offline state of memory.
-                    - at write: user can specify "online_kernel",
-
-                    "online_movable", "online", "offline" command
-                    which will be performed on all sections in the block.
+``online``	    read-write: simplified interface to trigger onlining /
+		    offlining and to observe the state of a memory block.
+		    When onlining, the zone is selected automatically.
 ``phys_device``	    read-only: legacy interface only ever used on s390x to
 		    expose the covered storage increment.
+``phys_index``	    read-only: the memory block id (XXX).
 ``removable``	    read-only: legacy interface that indicated whether a memory
-		    block was likely to be offlineable or not.  Newer kernel
-		    versions return "1" if and only if the kernel supports
-		    memory offlining.
-``valid_zones``     read-only: designed to show by which zone memory provided by
-		    a memory block is managed, and to show by which zone memory
-		    provided by an offline memory block could be managed when
-		    onlining.
+		    block was likely to be offlineable or not. Nowadays, the
+		    kernel return ``1`` if and only if it supports memory
+		    offlining.
+``state``	    read-write: advanced interface to trigger onlining /
+		    offlining and to observe the state of a memory block.
 
-		    The first column shows it`s default zone.
+		    When writing, ``online``, ``offline``, ``online_kernel`` and
+		    ``online_movable`` are supported.
 
-		    "memory6/valid_zones: Normal Movable" shows this memoryblock
-		    can be onlined to ZONE_NORMAL by default and to ZONE_MOVABLE
-		    by online_movable.
+		    ``online_movable`` specifies onlining to ZONE_MOVABLE.
+		    ``online_kernel`` specifies onlining to the default kernel
+		    zone for the memory block, such as ZONE_NORMAL.
+                    ``online`` let's the kernel select the zone automatically.
 
-		    "memory7/valid_zones: Movable Normal" shows this memoryblock
-		    can be onlined to ZONE_MOVABLE by default and to ZONE_NORMAL
-		    by online_kernel.
+		    When reading, ``online``, ``offline`` and ``going-offline``
+		    may be returned.
+``uevent``	    read-write: generic uevent file for devices.
+``valid_zones``     read-only: when a block is online, shows the zone it
+		    belongs to; when a block is offline, shows what zone will
+		    manage it when the block will be onlined.
+
+		    For online memory blocks, ``DMA``, ``DMA32``, ``Normal``,
+		    ``Movable`` and ``none`` may be returned. ``none`` indicates
+		    that memory provided by a memory block is managed by
+		    multiple zones or spans multiple nodes; such memory blocks
+		    cannot be offlined. ``Movable`` indicates ZONE_MOVABLE.
+		    Other values indicate a kernel zone.
+
+		    For offline memory blocks, the first column shows the
+		    zone the kernel would select when onlining the memory block
+		    right now without further specifying a zone.
+
+		    Availability depends on the CONFIG_MEMORY_HOTREMOVE
+		    kernel configuration option.
 =================== ============================================================
 
 .. note::
 
-  These directories/files appear after physical memory hotplug phase.
+  If the CONFIG_NUMA kernel configuration option is enabled, the memoryXXX/
+  directories can also be accessed via symbolic links located in the
+  ``/sys/devices/system/node/node*`` directories.
 
-If CONFIG_NUMA is enabled the memoryXXX/ directories can also be accessed
-via symbolic links located in the ``/sys/devices/system/node/node*`` directories.
-
-For example::
+  For example::
 
 	/sys/devices/system/node/node0/memory9 -> ../../memory/memory9
 
-A backlink will also be created::
+  A backlink will also be created::
 
 	/sys/devices/system/memory/memory9/node0 -> ../../node/node0
 
-.. _memory_hotplug_physical_mem:
+Command Line Parameters
+-----------------------
 
-Physical memory hot-add phase
-=============================
+Some command line parameters affect memory hot(un)plug handling. The following
+command line parameters are relevant:
 
-Hardware(Firmware) Support
---------------------------
+======================== =======================================================
+``memhp_default_state``	 configure auto-onlining by essentially setting
+                         ``/sys/devices/system/memory/auto_online_blocks``.
+``movablecore``		 configure automatic zone selection of the kernel. When
+			 set, the kernel will default to ZONE_MOVABLE, unless
+			 other zones can be kept contiguous.
+======================== =======================================================
 
-On x86_64/ia64 platform, memory hotplug by ACPI is supported.
+Module Parameters
+------------------
 
-In general, the firmware (ACPI) which supports memory hotplug defines
-memory class object of _HID "PNP0C80". When a notify is asserted to PNP0C80,
-Linux's ACPI handler does hot-add memory to the system and calls a hotplug udev
-script. This will be done automatically.
+Instead of additional command line parameters or sysfs files, the
+``memory_hotplug`` subsystem now provides a dedicated namespace for module
+parameters. Module parameters can be set via the command line by predicating
+them with ``memory_hotplug.`` such as::
 
-But scripts for memory hotplug are not contained in generic udev package(now).
-You may have to write it by yourself or online/offline memory by hand.
-Please see :ref:`memory_hotplug_how_to_online_memory` and
-:ref:`memory_hotplug_how_to_offline_memory`.
+	memory_hotplug.memmap_on_memory=1
 
-If firmware supports NUMA-node hotplug, and defines an object _HID "ACPI0004",
-"PNP0A05", or "PNP0A06", notification is asserted to it, and ACPI handler
-calls hotplug code for all of objects which are defined in it.
-If memory device is found, memory hotplug code will be called.
+and they can be observed (and some even modified at runtime) via::
 
-Notify memory hot-add event by hand
------------------------------------
+	/sys/modules/memory_hotplug/parameters/
 
-On some architectures, the firmware may not notify the kernel of a memory
-hotplug event.  Therefore, the memory "probe" interface is supported to
-explicitly notify the kernel.  This interface depends on
-CONFIG_ARCH_MEMORY_PROBE and can be configured on powerpc, sh, and x86
-if hotplug is supported, although for x86 this should be handled by ACPI
-notification.
+The following module parameters are currently defined:
 
-Probe interface is located at::
+======================== =======================================================
+``memmap_on_memory``	 read-write: Allocate memory for the memmap from the
+			 added memory block itself. Even if enabled, actual
+			 support depends on various other system properties and
+			 should only be regarded as a hint whether the behavior
+			 would be desired.
 
-	/sys/devices/system/memory/probe
+			 While allocating the memmap from the memory block
+			 itself makes memory hotplug less likely to fail and
+			 keeps the memmap on the same NUMA node in any case, it
+			 can fragment physical memory in a way that huge pages
+			 in bigger granularity cannot be formed on hotplugged
+			 memory.
+======================== =======================================================
 
-You can tell the physical address of new memory to the kernel by::
+ZONE_MOVABLE
+============
 
-	% echo start_address_of_new_memory > /sys/devices/system/memory/probe
+ZONE_MOVABLE is an important mechanism for more reliable memory offlining.
+Further, having system RAM managed by ZONE_MOVABLE instead of one of the
+kernel zones can increase the number of possible transparent huge pages and
+dynamically allocated huge pages.
 
-Then, [start_address_of_new_memory, start_address_of_new_memory +
-memory_block_size] memory range is hot-added. In this case, hotplug script is
-not called (in current implementation). You'll have to online memory by
-yourself.  Please see :ref:`memory_hotplug_how_to_online_memory`.
+Most kernel allocations are unmovable. Important examples include the memory
+map (usually 1/64ths of memory), page tables, and kmalloc(). Such allocations
+can only be served from the kernel zones.
 
-Logical Memory hot-add phase
-============================
+Most user space pages, such as anonymous memory, and page cache pages are
+movable. Such allocations can be served from ZONE_MOVABLE and the kernel zones.
 
-State of memory
+Only movable allocations are served from ZONE_MOVABLE, resulting in unmovable
+allocations being limited to the kernel zones. Without ZONE_MOVABLE, there is
+absolutely no guarantee whether a memory block can be offlined successfully.
+
+Zone Imbalances
 ---------------
 
-To see (online/offline) state of a memory block, read 'state' file::
+Having too much system RAM managed by ZONE_MOVABLE is called a zone imbalance,
+which can harm the system or degrade performance. As one example, the kernel
+might crash because it runs out of free memory for unmovable allocations,
+although there is still plenty of free memory left in ZONE_MOVABLE.
 
-	% cat /sys/device/system/memory/memoryXXX/state
+Usually, MOVABLE:KERNEL ratios of up to 3:1 or even 4:1 are fine. Ratios of 63:1
+are definitely impossible due to the overhead for the memory map.
 
-
-- If the memory block is online, you'll read "online".
-- If the memory block is offline, you'll read "offline".
-
-
-.. _memory_hotplug_how_to_online_memory:
-
-How to online memory
---------------------
-
-When the memory is hot-added, the kernel decides whether or not to "online"
-it according to the policy which can be read from "auto_online_blocks" file::
-
-	% cat /sys/devices/system/memory/auto_online_blocks
-
-The default depends on the CONFIG_MEMORY_HOTPLUG_DEFAULT_ONLINE kernel config
-option. If it is disabled the default is "offline" which means the newly added
-memory is not in a ready-to-use state and you have to "online" the newly added
-memory blocks manually. Automatic onlining can be requested by writing "online"
-to "auto_online_blocks" file::
-
-	% echo online > /sys/devices/system/memory/auto_online_blocks
-
-This sets a global policy and impacts all memory blocks that will subsequently
-be hotplugged. Currently offline blocks keep their state. It is possible, under
-certain circumstances, that some memory blocks will be added but will fail to
-online. User space tools can check their "state" files
-(``/sys/devices/system/memory/memoryXXX/state``) and try to online them manually.
-
-If the automatic onlining wasn't requested, failed, or some memory block was
-offlined it is possible to change the individual block's state by writing to the
-"state" file::
-
-	% echo online > /sys/devices/system/memory/memoryXXX/state
-
-This onlining will not change the ZONE type of the target memory block,
-If the memory block doesn't belong to any zone an appropriate kernel zone
-(usually ZONE_NORMAL) will be used unless movable_node kernel command line
-option is specified when ZONE_MOVABLE will be used.
-
-You can explicitly request to associate it with ZONE_MOVABLE by::
-
-	% echo online_movable > /sys/devices/system/memory/memoryXXX/state
-
-.. note:: current limit: this memory block must be adjacent to ZONE_MOVABLE
-
-Or you can explicitly request a kernel zone (usually ZONE_NORMAL) by::
-
-	% echo online_kernel > /sys/devices/system/memory/memoryXXX/state
-
-.. note:: current limit: this memory block must be adjacent to ZONE_NORMAL
-
-An explicit zone onlining can fail (e.g. when the range is already within
-and existing and incompatible zone already).
-
-After this, memory block XXX's state will be 'online' and the amount of
-available memory will be increased.
-
-This may be changed in future.
-
-Logical memory remove
-=====================
-
-Memory offline and ZONE_MOVABLE
--------------------------------
-
-Memory offlining is more complicated than memory online. Because memory offline
-has to make the whole memory block be unused, memory offline can fail if
-the memory block includes memory which cannot be freed.
-
-In general, memory offline can use 2 techniques.
-
-(1) reclaim and free all memory in the memory block.
-(2) migrate all pages in the memory block.
-
-In the current implementation, Linux's memory offline uses method (2), freeing
-all  pages in the memory block by page migration. But not all pages are
-migratable. Under current Linux, migratable pages are anonymous pages and
-page caches. For offlining a memory block by migration, the kernel has to
-guarantee that the memory block contains only migratable pages.
-
-Now, a boot option for making a memory block which consists of migratable pages
-is supported. By specifying "kernelcore=" or "movablecore=" boot option, you can
-create ZONE_MOVABLE...a zone which is just used for movable pages.
-(See also Documentation/admin-guide/kernel-parameters.rst)
-
-Assume the system has "TOTAL" amount of memory at boot time, this boot option
-creates ZONE_MOVABLE as following.
-
-1) When kernelcore=YYYY boot option is used,
-   Size of memory not for movable pages (not for offline) is YYYY.
-   Size of memory for movable pages (for offline) is TOTAL-YYYY.
-
-2) When movablecore=ZZZZ boot option is used,
-   Size of memory not for movable pages (not for offline) is TOTAL - ZZZZ.
-   Size of memory for movable pages (for offline) is ZZZZ.
+Actual safe zone ratios depend on the workload. Extreme cases, like excessive
+long-term pinning of pages, might not be able to deal with ZONE_MOVABLE at all.
 
 .. note::
 
-   Unfortunately, there is no information to show which memory block belongs
-   to ZONE_MOVABLE. This is TBD.
+  CMA memory part of a kernel zone essentially behaves like memory in
+  ZONE_MOVABLE and similar considerations apply, especially when combining
+  CMA with ZONE_MOVABLE.
 
-   Memory offlining can fail when dissolving a free huge page on ZONE_MOVABLE
-   and the feature of freeing unused vmemmap pages associated with each hugetlb
-   page is enabled.
+ZONE_MOVABLE Sizing Considerations
+----------------------------------
 
-   This can happen when we have plenty of ZONE_MOVABLE memory, but not enough
-   kernel memory to allocate vmemmmap pages.  We may even be able to migrate
-   huge page contents, but will not be able to dissolve the source huge page.
-   This will prevent an offline operation and is unfortunate as memory offlining
-   is expected to succeed on movable zones.  Users that depend on memory hotplug
-   to succeed for movable zones should carefully consider whether the memory
-   savings gained from this feature are worth the risk of possibly not being
-   able to offline memory in certain situations.
+We usually expect that a large portion of available system RAM will actually
+be consumed by user space, either directly or indirectly via the page cache. In
+the normal case, ZONE_MOVABLE can be used when allocating such pages just fine.
 
-.. note::
-   Techniques that rely on long-term pinnings of memory (especially, RDMA and
-   vfio) are fundamentally problematic with ZONE_MOVABLE and, therefore, memory
-   hot remove. Pinned pages cannot reside on ZONE_MOVABLE, to guarantee that
-   memory can still get hot removed - be aware that pinning can fail even if
-   there is plenty of free memory in ZONE_MOVABLE. In addition, using
-   ZONE_MOVABLE might make page pinning more expensive, because pages have to be
-   migrated off that zone first.
+With that in mind, it makes sense that we can have a big portion of system RAM
+managed by ZONE_MOVABLE. However, there are some things to consider when using
+ZONE_MOVABLE, especially when fine-tuning zone ratios:
 
-.. _memory_hotplug_how_to_offline_memory:
+- Having a lot of offline memory blocks. Even offline memory blocks consume
+  memory for metadata and page tables in the direct map; having a lot of offline
+  memory blocks is not a typical case, though.
 
-How to offline memory
----------------------
+- Memory ballooning without balloon compaction is incompatible with
+  ZONE_MOVABLE. Only some implementations, such as virtio-balloon and
+  pseries CMM, fully support balloon compaction.
 
-You can offline a memory block by using the same sysfs interface that was used
-in memory onlining::
+  Further, the CONFIG_BALLOON_COMPACTION kernel configuration option might be
+  disabled. In that case, balloon inflation will only perform unmovable
+  allocations and silently create a zone imbalance, usually triggered by
+  inflation requests from the hypervisor.
 
-	% echo offline > /sys/devices/system/memory/memoryXXX/state
+- Gigantic pages are unmovable, resulting in user space consuming a
+  lot of unmovable memory.
 
-If offline succeeds, the state of the memory block is changed to be "offline".
-If it fails, some error core (like -EBUSY) will be returned by the kernel.
-Even if a memory block does not belong to ZONE_MOVABLE, you can try to offline
-it.  If it doesn't contain 'unmovable' memory, you'll get success.
+- Huge pages are unmovable when an architectures does not support huge
+  page migration, resulting in a similar issue as with gigantic pages.
 
-A memory block under ZONE_MOVABLE is considered to be able to be offlined
-easily.  But under some busy state, it may return -EBUSY. Even if a memory
-block cannot be offlined due to -EBUSY, you can retry offlining it and may be
-able to offline it (or not). (For example, a page is referred to by some kernel
-internal call and released soon.)
+- Page tables are unmovable. Excessive swapping, mapping extremely large
+  files or ZONE_DEVICE memory can be problematic, although only really relevant
+  in corner cases. When we manage a lot of user space memory that has been
+  swapped out or is served from a file/persistent memory/... we still need a lot
+  of page tables to manage that memory once user space accessed that memory.
 
-Consideration:
-  Memory hotplug's design direction is to make the possibility of memory
-  offlining higher and to guarantee unplugging memory under any situation. But
-  it needs more work. Returning -EBUSY under some situation may be good because
-  the user can decide to retry more or not by himself. Currently, memory
-  offlining code does some amount of retry with 120 seconds timeout.
+- In certain DAX configurations the memory map for the device memory will be
+  allocated from the kernel zones.
 
-Physical memory remove
-======================
+- KASAN can have a significant memory overhead, for example, consuming 1/8th of
+  the total system memory size as (unmovable) tracking metadata.
 
-Need more implementation yet....
- - Notification completion of remove works by OS to firmware.
- - Guard from remove if not yet.
+- Long-term pinning of pages. Techniques that rely on long-term pinnings
+  (especially, RDMA and vfio/mdev) are fundamentally problematic with
+  ZONE_MOVABLE, and therefore, memory offlining. Pinned pages cannot reside
+  on ZONE_MOVABLE as that would turn these pages unmovable. Therefore, they
+  have to be migrated off that zone while pinning. Pinning a page can fail
+  even if there is plenty of free memory in ZONE_MOVABLE.
 
+  In addition, using ZONE_MOVABLE might make page pinning more expensive,
+  because of the page migration overhead.
 
-Locking Internals
-=================
+By default, all the memory configured at boot time is managed by the kernel
+zones and ZONE_MOVABLE is not used.
 
-When adding/removing memory that uses memory block devices (i.e. ordinary RAM),
-the device_hotplug_lock should be held to:
+To enable ZONE_MOVABLE to include the memory present at boot and to control the
+ratio between movable and kernel zones there are two command line options:
+``kernelcore=`` and ``movablecore=``. See
+Documentation/admin-guide/kernel-parameters.rst for their description.
 
-- synchronize against online/offline requests (e.g. via sysfs). This way, memory
-  block devices can only be accessed (.online/.state attributes) by user
-  space once memory has been fully added. And when removing memory, we
-  know nobody is in critical sections.
-- synchronize against CPU hotplug and similar (e.g. relevant for ACPI and PPC)
+Memory Offlining and ZONE_MOVABLE
+---------------------------------
 
-Especially, there is a possible lock inversion that is avoided using
-device_hotplug_lock when adding memory and user space tries to online that
-memory faster than expected:
+Even with ZONE_MOVABLE, there are some corner cases where offlining a memory
+block might fail:
 
-- device_online() will first take the device_lock(), followed by
-  mem_hotplug_lock
-- add_memory_resource() will first take the mem_hotplug_lock, followed by
-  the device_lock() (while creating the devices, during bus_add_device()).
+- Memory blocks with memory holes; this applies to memory blocks present during
+  boot and can apply to memory blocks hotplugged via the XEN balloon and the
+  Hyper-V balloon.
 
-As the device is visible to user space before taking the device_lock(), this
-can result in a lock inversion.
+- Mixed NUMA nodes and mixed zones within a single memory block prevent memory
+  offlining; this applies to memory blocks present during boot only.
 
-onlining/offlining of memory should be done via device_online()/
-device_offline() - to make sure it is properly synchronized to actions
-via sysfs. Holding device_hotplug_lock is advised (to e.g. protect online_type)
+- Special memory blocks prevented by the system from getting offlined. Examples
+  include any memory available during boot on arm64 or memory blocks spanning
+  the crashkernel area on s390x; this usually applies to memory blocks present
+  during boot only.
 
-When adding/removing/onlining/offlining memory or adding/removing
-heterogeneous/device memory, we should always hold the mem_hotplug_lock in
-write mode to serialise memory hotplug (e.g. access to global/zone
-variables).
+- Memory blocks overlapping with CMA areas cannot be offlined, this applies to
+  memory blocks present during boot only.
 
-In addition, mem_hotplug_lock (in contrast to device_hotplug_lock) in read
-mode allows for a quite efficient get_online_mems/put_online_mems
-implementation, so code accessing memory can protect from that memory
-vanishing.
+- Concurrent activity that operates on the same physical memory area, such as
+  allocating gigantic pages, can result in temporary offlining failures.
 
+- Out of memory when dissolving huge pages, especially when freeing unused
+  vmemmap pages associated with each hugetlb page is enabled.
 
-Future Work
-===========
+  Offlining code may be able to migrate huge page contents, but may not be able
+  to dissolve the source huge page because it fails allocating (unmovable) pages
+  for the vmemmap, because the system might not have free memory in the kernel
+  zones left.
 
-  - allowing memory hot-add to ZONE_MOVABLE. maybe we need some switch like
-    sysctl or new control file.
-  - showing memory block and physical device relationship.
-  - test and make it better memory offlining.
-  - support HugeTLB page migration and offlining.
-  - memmap removing at memory offline.
-  - physical remove memory.
+  Users that depend on memory offlining to succeed for movable zones should
+  carefully consider whether the memory savings gained from this feature are
+  worth the risk of possibly not being able to offline memory in certain
+  situations.
+
+Further, when running into out of memory situations while migrating pages, or
+when still encountering permanently unmovable pages within ZONE_MOVABLE
+(-> BUG), memory offlining will keep retrying until it eventually succeeds.
+
+When offlining is triggered from user space, the offlining context can be
+terminated by sending a fatal signal. A timeout based offlining can easily be
+implemented via::
+
+	% timeout $TIMEOUT offline_block | failure_handling

Documentation/dev-tools/kfence.rst

···
 A typical out-of-bounds access looks like this::
 
     ==================================================================
-    BUG: KFENCE: out-of-bounds read in test_out_of_bounds_read+0xa3/0x22b
+    BUG: KFENCE: out-of-bounds read in test_out_of_bounds_read+0xa6/0x234
 
-    Out-of-bounds read at 0xffffffffb672efff (1B left of kfence-#17):
-     test_out_of_bounds_read+0xa3/0x22b
-     kunit_try_run_case+0x51/0x85
+    Out-of-bounds read at 0xffff8c3f2e291fff (1B left of kfence-#72):
+     test_out_of_bounds_read+0xa6/0x234
+     kunit_try_run_case+0x61/0xa0
      kunit_generic_run_threadfn_adapter+0x16/0x30
-     kthread+0x137/0x160
+     kthread+0x176/0x1b0
      ret_from_fork+0x22/0x30
 
-    kfence-#17 [0xffffffffb672f000-0xffffffffb672f01f, size=32, cache=kmalloc-32] allocated by task 507:
-     test_alloc+0xf3/0x25b
-     test_out_of_bounds_read+0x98/0x22b
-     kunit_try_run_case+0x51/0x85
+    kfence-#72: 0xffff8c3f2e292000-0xffff8c3f2e29201f, size=32, cache=kmalloc-32
+
+    allocated by task 484 on cpu 0 at 32.919330s:
+     test_alloc+0xfe/0x738
+     test_out_of_bounds_read+0x9b/0x234
+     kunit_try_run_case+0x61/0xa0
      kunit_generic_run_threadfn_adapter+0x16/0x30
-     kthread+0x137/0x160
+     kthread+0x176/0x1b0
      ret_from_fork+0x22/0x30
 
-    CPU: 4 PID: 107 Comm: kunit_try_catch Not tainted 5.8.0-rc6+ #7
-    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1 04/01/2014
+    CPU: 0 PID: 484 Comm: kunit_try_catch Not tainted 5.13.0-rc3+ #7
+    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
     ==================================================================
 
 The header of the report provides a short summary of the function involved in
···
     ==================================================================
     BUG: KFENCE: use-after-free read in test_use_after_free_read+0xb3/0x143
 
-    Use-after-free read at 0xffffffffb673dfe0 (in kfence-#24):
+    Use-after-free read at 0xffff8c3f2e2a0000 (in kfence-#79):
      test_use_after_free_read+0xb3/0x143
-     kunit_try_run_case+0x51/0x85
+     kunit_try_run_case+0x61/0xa0
      kunit_generic_run_threadfn_adapter+0x16/0x30
-     kthread+0x137/0x160
+     kthread+0x176/0x1b0
      ret_from_fork+0x22/0x30
 
-    kfence-#24 [0xffffffffb673dfe0-0xffffffffb673dfff, size=32, cache=kmalloc-32] allocated by task 507:
-     test_alloc+0xf3/0x25b
+    kfence-#79: 0xffff8c3f2e2a0000-0xffff8c3f2e2a001f, size=32, cache=kmalloc-32
+
+    allocated by task 488 on cpu 2 at 33.871326s:
+     test_alloc+0xfe/0x738
      test_use_after_free_read+0x76/0x143
-     kunit_try_run_case+0x51/0x85
+     kunit_try_run_case+0x61/0xa0
      kunit_generic_run_threadfn_adapter+0x16/0x30
-     kthread+0x137/0x160
+     kthread+0x176/0x1b0
      ret_from_fork+0x22/0x30
 
-    freed by task 507:
+    freed by task 488 on cpu 2 at 33.871358s:
      test_use_after_free_read+0xa8/0x143
-     kunit_try_run_case+0x51/0x85
+     kunit_try_run_case+0x61/0xa0
      kunit_generic_run_threadfn_adapter+0x16/0x30
-     kthread+0x137/0x160
+     kthread+0x176/0x1b0
      ret_from_fork+0x22/0x30
 
-    CPU: 4 PID: 109 Comm: kunit_try_catch Tainted: G        W         5.8.0-rc6+ #7
-    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1 04/01/2014
+    CPU: 2 PID: 488 Comm: kunit_try_catch Tainted: G    B             5.13.0-rc3+ #7
+    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
     ==================================================================
 
 KFENCE also reports on invalid frees, such as double-frees::
···
     ==================================================================
     BUG: KFENCE: invalid free in test_double_free+0xdc/0x171
 
-    Invalid free of 0xffffffffb6741000:
+    Invalid free of 0xffff8c3f2e2a4000 (in kfence-#81):
      test_double_free+0xdc/0x171
-     kunit_try_run_case+0x51/0x85
+     kunit_try_run_case+0x61/0xa0
      kunit_generic_run_threadfn_adapter+0x16/0x30
-     kthread+0x137/0x160
+     kthread+0x176/0x1b0
      ret_from_fork+0x22/0x30
 
-    kfence-#26 [0xffffffffb6741000-0xffffffffb674101f, size=32, cache=kmalloc-32] allocated by task 507:
-     test_alloc+0xf3/0x25b
+    kfence-#81: 0xffff8c3f2e2a4000-0xffff8c3f2e2a401f, size=32, cache=kmalloc-32
+
+    allocated by task 490 on cpu 1 at 34.175321s:
+     test_alloc+0xfe/0x738
      test_double_free+0x76/0x171
-     kunit_try_run_case+0x51/0x85
+     kunit_try_run_case+0x61/0xa0
      kunit_generic_run_threadfn_adapter+0x16/0x30
-     kthread+0x137/0x160
+     kthread+0x176/0x1b0
      ret_from_fork+0x22/0x30
 
-    freed by task 507:
+    freed by task 490 on cpu 1 at 34.175348s:
      test_double_free+0xa8/0x171
-     kunit_try_run_case+0x51/0x85
+     kunit_try_run_case+0x61/0xa0
      kunit_generic_run_threadfn_adapter+0x16/0x30
-     kthread+0x137/0x160
+     kthread+0x176/0x1b0
      ret_from_fork+0x22/0x30
 
-    CPU: 4 PID: 111 Comm: kunit_try_catch Tainted: G        W         5.8.0-rc6+ #7
-    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1 04/01/2014
+    CPU: 1 PID: 490 Comm: kunit_try_catch Tainted: G    B             5.13.0-rc3+ #7
+    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
     ==================================================================
 
 KFENCE also uses pattern-based redzones on the other side of an object's guard
···
     ==================================================================
     BUG: KFENCE: memory corruption in test_kmalloc_aligned_oob_write+0xef/0x184
 
-    Corrupted memory at 0xffffffffb6797ff9 [ 0xac . . . . . . ] (in kfence-#69):
+    Corrupted memory at 0xffff8c3f2e33aff9 [ 0xac . . . . . . ] (in kfence-#156):
      test_kmalloc_aligned_oob_write+0xef/0x184
-     kunit_try_run_case+0x51/0x85
+     kunit_try_run_case+0x61/0xa0
      kunit_generic_run_threadfn_adapter+0x16/0x30
-     kthread+0x137/0x160
+     kthread+0x176/0x1b0
      ret_from_fork+0x22/0x30
 
-    kfence-#69 [0xffffffffb6797fb0-0xffffffffb6797ff8, size=73, cache=kmalloc-96] allocated by task 507:
-     test_alloc+0xf3/0x25b
+    kfence-#156: 0xffff8c3f2e33afb0-0xffff8c3f2e33aff8, size=73, cache=kmalloc-96
+
+    allocated by task 502 on cpu 7 at 42.159302s:
+     test_alloc+0xfe/0x738
      test_kmalloc_aligned_oob_write+0x57/0x184
-     kunit_try_run_case+0x51/0x85
+     kunit_try_run_case+0x61/0xa0
      kunit_generic_run_threadfn_adapter+0x16/0x30
-     kthread+0x137/0x160
+     kthread+0x176/0x1b0
      ret_from_fork+0x22/0x30
 
-    CPU: 4 PID: 120 Comm: kunit_try_catch Tainted: G        W         5.8.0-rc6+ #7
-    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1 04/01/2014
+    CPU: 7 PID: 502 Comm: kunit_try_catch Tainted: G    B             5.13.0-rc3+ #7
+    Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014
     ==================================================================
 
 For such errors, the address where the corruption occurred as well as the

Documentation/kbuild/llvm.rst

···
 ------------
 
 - `Website <https://clangbuiltlinux.github.io/>`_
-- `Mailing List <https://groups.google.com/forum/#!forum/clang-built-linux>`_: <[e-mail]>
+- `Mailing List <https://lore.kernel.org/llvm/>`_: <[e-mail]>
+- `Old Mailing List Archives <https://groups.google.com/g/clang-built-linux>`_
 - `Issue Tracker <https://github.com/ClangBuiltLinux/linux/issues>`_
-- IRC: #clangbuiltlinux on chat.freenode.net
+- IRC: #clangbuiltlinux on irc.libera.chat
 - `Telegram <https://t.me/ClangBuiltLinux>`_: @ClangBuiltLinux
 - `Wiki <https://github.com/ClangBuiltLinux/linux/wiki>`_
 - `Beginner Bugs <https://github.com/ClangBuiltLinux/linux/issues?q=is%3Aopen+is%3Aissue+label%3A%22good+first+issue%22>`_

Documentation/vm/damon/api.rst

···
+.. SPDX-License-Identifier: GPL-2.0
+
+=============
+API Reference
+=============
+
+Kernel space programs can use every feature of DAMON using below APIs.  All you
+need to do is including ``damon.h``, which is located in ``include/linux/`` of
+the source tree.
+
+Structures
+==========
+
+.. kernel-doc:: include/linux/damon.h
+
+
+Functions
+=========
+
+.. kernel-doc:: mm/damon/core.c

Documentation/vm/damon/design.rst

···
+.. SPDX-License-Identifier: GPL-2.0
+
+======
+Design
+======
+
+Configurable Layers
+===================
+
+DAMON provides data access monitoring functionality while making the accuracy
+and the overhead controllable.  The fundamental access monitorings require
+primitives that dependent on and optimized for the target address space.  On
+the other hand, the accuracy and overhead tradeoff mechanism, which is the core
+of DAMON, is in the pure logic space.  DAMON separates the two parts in
+different layers and defines its interface to allow various low level
+primitives implementations configurable with the core logic.
+
+Due to this separated design and the configurable interface, users can extend
+DAMON for any address space by configuring the core logics with appropriate low
+level primitive implementations.  If appropriate one is not provided, users can
+implement the primitives on their own.
+
+For example, physical memory, virtual memory, swap space, those for specific
+processes, NUMA nodes, files, and backing memory devices would be supportable.
+Also, if some architectures or devices support special optimized access check
+primitives, those will be easily configurable.
+
+
+Reference Implementations of Address Space Specific Primitives
+==============================================================
+
+The low level primitives for the fundamental access monitoring are defined in
+two parts:
+
+1. Identification of the monitoring target address range for the address space.
+2. Access check of specific address range in the target space.
+
+DAMON currently provides the implementation of the primitives for only the
+virtual address spaces. Below two subsections describe how it works.
+
+
+VMA-based Target Address Range Construction
+-------------------------------------------
+
+Only small parts in the super-huge virtual address space of the processes are
+mapped to the physical memory and accessed.  Thus, tracking the unmapped
+address regions is just wasteful.  However, because DAMON can deal with some
+level of noise using the adaptive regions adjustment mechanism, tracking every
+mapping is not strictly required but could even incur a high overhead in some
+cases.  That said, too huge unmapped areas inside the monitoring target should
+be removed to not take the time for the adaptive mechanism.
+
+For the reason, this implementation converts the complex mappings to three
+distinct regions that cover every mapped area of the address space.  The two
+gaps between the three regions are the two biggest unmapped areas in the given
+address space.  The two biggest unmapped areas would be the gap between the
+heap and the uppermost mmap()-ed region, and the gap between the lowermost
+mmap()-ed region and the stack in most of the cases.  Because these gaps are
+exceptionally huge in usual address spaces, excluding these will be sufficient
+to make a reasonable trade-off.  Below shows this in detail::
+
+    <heap>
+    <BIG UNMAPPED REGION 1>
+    <uppermost mmap()-ed region>
+    (small mmap()-ed regions and munmap()-ed regions)
+    <lowermost mmap()-ed region>
+    <BIG UNMAPPED REGION 2>
+    <stack>
+
+
+PTE Accessed-bit Based Access Check
+-----------------------------------
+
+The implementation for the virtual address space uses PTE Accessed-bit for
+basic access checks.  It finds the relevant PTE Accessed bit from the address
+by walking the page table for the target task of the address.  In this way, the
+implementation finds and clears the bit for next sampling target address and
+checks whether the bit set again after one sampling period.  This could disturb
+other kernel subsystems using the Accessed bits, namely Idle page tracking and
+the reclaim logic.  To avoid such disturbances, DAMON makes it mutually
+exclusive with Idle page tracking and uses ``PG_idle`` and ``PG_young`` page
+flags to solve the conflict with the reclaim logic, as Idle page tracking does.
+
+
+Address Space Independent Core Mechanisms
+=========================================
+
+Below four sections describe each of the DAMON core mechanisms and the five
+monitoring attributes, ``sampling interval``, ``aggregation interval``,
+``regions update interval``, ``minimum number of regions``, and ``maximum
+number of regions``.
+
+
+Access Frequency Monitoring
+---------------------------
+
+The output of DAMON says what pages are how frequently accessed for a given
+duration.  The resolution of the access frequency is controlled by setting
+``sampling interval`` and ``aggregation interval``.  In detail, DAMON checks
+access to each page per ``sampling interval`` and aggregates the results.  In
+other words, counts the number of the accesses to each page.  After each
+``aggregation interval`` passes, DAMON calls callback functions that previously
+registered by users so that users can read the aggregated results and then
+clears the results.  This can be described in below simple pseudo-code::
+
+    while monitoring_on:
+        for page in monitoring_target:
+            if accessed(page):
+                nr_accesses[page] += 1
+        if time() % aggregation_interval == 0:
+            for callback in user_registered_callbacks:
+                callback(monitoring_target, nr_accesses)
+            for page in monitoring_target:
+                nr_accesses[page] = 0
+        sleep(sampling interval)
+
+The monitoring overhead of this mechanism will arbitrarily increase as the
+size of the target workload grows.
+
+
+Region Based Sampling
+---------------------
+
+To avoid the unbounded increase of the overhead, DAMON groups adjacent pages
+that assumed to have the same access frequencies into a region.  As long as the
+assumption (pages in a region have the same access frequencies) is kept, only
+one page in the region is required to be checked.  Thus, for each ``sampling
+interval``, DAMON randomly picks one page in each region, waits for one
+``sampling interval``, checks whether the page is accessed meanwhile, and
+increases the access frequency of the region if so.  Therefore, the monitoring
+overhead is controllable by setting the number of regions.  DAMON allows users
+to set the minimum and the maximum number of regions for the trade-off.
+
+This scheme, however, cannot preserve the quality of the output if the
+assumption is not guaranteed.
+
+
+Adaptive Regions Adjustment
+---------------------------
+
+Even somehow the initial monitoring target regions are well constructed to
+fulfill the assumption (pages in same region have similar access frequencies),
+the data access pattern can be dynamically changed.  This will result in low
+monitoring quality.  To keep the assumption as much as possible, DAMON
+adaptively merges and splits each region based on their access frequency.
+
+For each ``aggregation interval``, it compares the access frequencies of
+adjacent regions and merges those if the frequency difference is small.  Then,
+after it reports and clears the aggregated access frequency of each region, it
+splits each region into two or three regions if the total number of regions
+will not exceed the user-specified maximum number of regions after the split.
+
+In this way, DAMON provides its best-effort quality and minimal overhead while
+keeping the bounds users set for their trade-off.
+
+
+Dynamic Target Space Updates Handling
+-------------------------------------
+
+The monitoring target address range could dynamically changed.  For example,
+virtual memory could be dynamically mapped and unmapped.  Physical memory could
+be hot-plugged.
+
+As the changes could be quite frequent in some cases, DAMON checks the dynamic
+memory mapping changes and applies it to the abstracted target area only for
+each of a user-specified time interval (``regions update interval``).

Documentation/vm/damon/faq.rst

···
+.. SPDX-License-Identifier: GPL-2.0
+
+==========================
+Frequently Asked Questions
+==========================
+
+Why a new subsystem, instead of extending perf or other user space tools?
+=========================================================================
+
+First, because it needs to be lightweight as much as possible so that it can be
+used online, any unnecessary overhead such as kernel - user space context
+switching cost should be avoided.  Second, DAMON aims to be used by other
+programs including the kernel.  Therefore, having a dependency on specific
+tools like perf is not desirable.  These are the two biggest reasons why DAMON
+is implemented in the kernel space.
+
+
+Can 'idle pages tracking' or 'perf mem' substitute DAMON?
+=========================================================
+
+Idle page tracking is a low level primitive for access check of the physical
+address space.  'perf mem' is similar, though it can use sampling to minimize
+the overhead.  On the other hand, DAMON is a higher-level framework for the
+monitoring of various address spaces.  It is focused on memory management
+optimization and provides sophisticated accuracy/overhead handling mechanisms.
+Therefore, 'idle pages tracking' and 'perf mem' could provide a subset of
+DAMON's output, but cannot substitute DAMON.
+
+
+Does DAMON support virtual memory only?
+=======================================
+
+No.  The core of the DAMON is address space independent.  The address space
+specific low level primitive parts including monitoring target regions
+constructions and actual access checks can be implemented and configured on the
+DAMON core by the users.  In this way, DAMON users can monitor any address
+space with any access check technique.
+
+Nonetheless, DAMON provides vma tracking and PTE Accessed bit check based
+implementations of the address space dependent functions for the virtual memory
+by default, for a reference and convenient use.  In near future, we will
+provide those for physical memory address space.
+
+
+Can I simply monitor page granularity?
+======================================
+
+Yes.  You can do so by setting the ``min_nr_regions`` attribute higher than the
+working set size divided by the page size.  Because the monitoring target
+regions size is forced to be ``>=page size``, the region split will make no
+effect.

Documentation/vm/damon/index.rst

···
+.. SPDX-License-Identifier: GPL-2.0
+
+==========================
+DAMON: Data Access MONitor
+==========================
+
+DAMON is a data access monitoring framework subsystem for the Linux kernel.
+The core mechanisms of DAMON (refer to :doc:`design` for the detail) make it
+
+ - *accurate* (the monitoring output is useful enough for DRAM level memory
+   management; It might not appropriate for CPU Cache levels, though),
+ - *light-weight* (the monitoring overhead is low enough to be applied online),
+   and
+ - *scalable* (the upper-bound of the overhead is in constant range regardless
+   of the size of target workloads).
+
+Using this framework, therefore, the kernel's memory management mechanisms can
+make advanced decisions.  Experimental memory management optimization works
+that incurring high data accesses monitoring overhead could implemented again.
+In user space, meanwhile, users who have some special workloads can write
+personalized applications for better understanding and optimizations of their
+workloads and systems.
+
+.. toctree::
+   :maxdepth: 2
+
+   faq
+   design
+   api
+   plans

Documentation/vm/index.rst

···
    arch_pgtable_helpers
    balance
    cleancache
+   damon/index
    free_page_reporting
    frontswap
    highmem

MAINTAINERS

···
 CLANG/LLVM BUILD SUPPORT
 M:	Nathan Chancellor <[e-mail]>
 M:	Nick Desaulniers <[e-mail]>
-L:	[e-mail]
+L:	[e-mail]
 S:	Supported
 W:	https://clangbuiltlinux.github.io/
 B:	https://github.com/ClangBuiltLinux/linux/issues
···
 M:	Kees Cook <[e-mail]>
 R:	Nathan Chancellor <[e-mail]>
 R:	Nick Desaulniers <[e-mail]>
-L:	[e-mail]
+L:	[e-mail]
 S:	Supported
 B:	https://github.com/ClangBuiltLinux/linux/issues
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/clang/features
···
 F:	net/ax25/ax25_out.c
 F:	net/ax25/ax25_timer.c
 F:	net/ax25/sysctl_net_ax25.c
+
+DATA ACCESS MONITOR
+M:	SeongJae Park <[e-mail]>
+L:	[e-mail]
+S:	Maintained
+F:	Documentation/admin-guide/mm/damon/
+F:	Documentation/vm/damon/
+F:	include/linux/damon.h
+F:	include/trace/events/damon.h
+F:	mm/damon/
+F:	tools/testing/selftests/damon/
 
 DAVICOM FAST ETHERNET (DMFE) NETWORK DRIVER
 L:	[e-mail]

arch/Kconfig

···
 	bool
 	help
 	  Architecture provides a function to run __do_softirq() on a
-	  seperate stack.
+	  separate stack.
 
 config PGTABLE_LEVELS
 	int

arch/alpha/include/asm/agp.h

···
 
 /* dummy for now */
 
-#define map_page_into_agp(page) 
-#define unmap_page_from_agp(page) 
+#define map_page_into_agp(page)		do { } while (0)
+#define unmap_page_from_agp(page)	do { } while (0)
 #define flush_agp_cache() mb()
 
 /* GATT allocation. Returns/accepts GATT kernel virtual address. */

arch/alpha/kernel/pci-sysfs.c

···
  * @sparse: address space type
  *
  * Use the bus mapping routines to map a PCI resource into userspace.
+ *
+ * Return: %0 on success, negative error code otherwise
  */
 static int pci_mmap_resource(struct kobject *kobj,
 			     struct bin_attribute *attr,
···
 
 /**
  * pci_remove_resource_files - cleanup resource files
- * @dev: dev to cleanup
+ * @pdev: pci_dev to cleanup
  *
  * If we created resource files for @dev, remove them from sysfs and
  * free their resources.
···
 }
 
 /**
- * pci_create_resource_files - create resource files in sysfs for @dev
- * @dev: dev in question
+ * pci_create_resource_files - create resource files in sysfs for @pdev
+ * @pdev: pci_dev in question
  *
  * Walk the resources in @dev creating files for each resource available.
+ *
+ * Return: %0 on success, or negative error code
  */
 int pci_create_resource_files(struct pci_dev *pdev)
 {
···
 
 /**
  * pci_adjust_legacy_attr - adjustment of legacy file attributes
- * @b: bus to create files under
+ * @bus: bus to create files under
  * @mmap_type: I/O port or memory
  *
  * Adjust file name and size for sparse mappings.

arch/arc/kernel/traps.c

···
 #include <asm/unaligned.h>
 #include <asm/kprobes.h>
 
-void __init trap_init(void)
-{
-	return;
-}
-
 void die(const char *str, struct pt_regs *regs, unsigned long address)
 {
 	show_kernel_fault_diag(str, regs, address);

arch/arm/configs/dove_defconfig

···
 CONFIG_SATA_MV=y
 CONFIG_NETDEVICES=y
 CONFIG_MV643XX_ETH=y
-CONFIG_INPUT_POLLDEV=y
 # CONFIG_INPUT_MOUSEDEV is not set
 CONFIG_INPUT_EVDEV=y
 # CONFIG_KEYBOARD_ATKBD is not set

arch/arm/configs/pxa_defconfig

···
 CONFIG_MWIFIEX=m
 CONFIG_MWIFIEX_SDIO=m
 CONFIG_INPUT_FF_MEMLESS=m
-CONFIG_INPUT_POLLDEV=y
 CONFIG_INPUT_MATRIXKMAP=y
 CONFIG_INPUT_MOUSEDEV=m
 CONFIG_INPUT_MOUSEDEV_SCREEN_X=640

arch/arm/kernel/traps.c

···
 	panic("Oops failed to kill thread");
 }
 
-void __init trap_init(void)
-{
-	return;
-}
-
 #ifdef CONFIG_KUSER_HELPERS
 static void __init kuser_init(void *vectors)
 {

arch/arm64/mm/mmu.c

···
 	return ret;
 }
 
-void arch_remove_memory(int nid, u64 start, u64 size,
-			struct vmem_altmap *altmap)
+void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
 {
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;

arch/h8300/kernel/traps.c

···
 {
 }
 
-void __init trap_init(void)
-{
-}
-
 asmlinkage void set_esp0(unsigned long ssp)
 {
 	current->thread.esp0 = ssp;

arch/hexagon/kernel/traps.c

···
 #define TRAP_SYSCALL	1
 #define TRAP_DEBUG	0xdb
 
-void __init trap_init(void)
-{
-}
-
 #ifdef CONFIG_GENERIC_BUG
 /* Maybe should resemble arch/sh/kernel/traps.c ?? */
 int is_valid_bugaddr(unsigned long addr)

arch/ia64/mm/init.c

···
 	return ret;
 }
 
-void arch_remove_memory(int nid, u64 start, u64 size,
-			struct vmem_altmap *altmap)
+void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
 {
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;

arch/mips/configs/lemote2f_defconfig

···
 CONFIG_R8169=y
 CONFIG_USB_USBNET=m
 CONFIG_USB_NET_CDC_EEM=m
-CONFIG_INPUT_POLLDEV=m
 CONFIG_INPUT_EVDEV=y
 # CONFIG_MOUSE_PS2_ALPS is not set
 # CONFIG_MOUSE_PS2_LOGIPS2PP is not set

arch/mips/configs/pic32mzda_defconfig

···
 CONFIG_SCSI_SCAN_ASYNC=y
 # CONFIG_SCSI_LOWLEVEL is not set
 CONFIG_INPUT_LEDS=m
-CONFIG_INPUT_POLLDEV=y
 CONFIG_INPUT_MOUSEDEV=m
 CONFIG_INPUT_EVDEV=y
 CONFIG_INPUT_EVBUG=m

arch/mips/configs/rt305x_defconfig

···
 CONFIG_PPP_ASYNC=m
 CONFIG_ISDN=y
 CONFIG_INPUT=m
-CONFIG_INPUT_POLLDEV=m
 # CONFIG_KEYBOARD_ATKBD is not set
 # CONFIG_INPUT_MOUSE is not set
 CONFIG_INPUT_MISC=y

arch/mips/configs/xway_defconfig

···
 CONFIG_PPP_ASYNC=m
 CONFIG_ISDN=y
 CONFIG_INPUT=m
-CONFIG_INPUT_POLLDEV=m
 # CONFIG_KEYBOARD_ATKBD is not set
 # CONFIG_INPUT_MOUSE is not set
 CONFIG_INPUT_MISC=y

arch/nds32/kernel/traps.c

···
 }
 
 extern char *exception_vector, *exception_vector_end;
-void __init trap_init(void)
-{
-	return;
-}
-
 void __init early_trap_init(void)
 {
 	unsigned long ivb = 0;

arch/nios2/kernel/traps.c

···
 	printk("%s\n", loglvl);
 }
 
-void __init trap_init(void)
-{
-	/* Nothing to do here */
-}
-
 /* Breakpoint handler */
 asmlinkage void breakpoint_c(struct pt_regs *fp)
 {

arch/openrisc/kernel/traps.c

···
 	die("Oops", regs, 9);
 }
 
-void __init trap_init(void)
-{
-	/* Nothing needs to be done */
-}
-
 asmlinkage void do_trap(struct pt_regs *regs, unsigned long address)
 {
 	force_sig_fault(SIGTRAP, TRAP_BRKPT, (void __user *)regs->pc);

arch/parisc/configs/generic-32bit_defconfig

···
 CONFIG_PPP_DEFLATE=m
 CONFIG_PPPOE=m
 # CONFIG_WLAN is not set
-CONFIG_INPUT_POLLDEV=y
 CONFIG_KEYBOARD_HIL_OLD=m
 CONFIG_KEYBOARD_HIL=m
 CONFIG_MOUSE_SERIAL=y

arch/parisc/kernel/traps.c

···
 
 	initialize_ivt(&fault_vector_20);
 }
-
-void __init trap_init(void)
-{
-}

arch/powerpc/kernel/traps.c

···
 	die("Bad kernel stack pointer", regs, SIGABRT);
 }
 
-void __init trap_init(void)
-{
-}
-
-
 #ifdef CONFIG_PPC_EMULATED_STATS
 
 #define WARN_EMULATED_SETUP(type)	.type = { .name = #type }

arch/powerpc/mm/mem.c

···
 	return rc;
 }
 
-void __ref arch_remove_memory(int nid, u64 start, u64 size,
-			      struct vmem_altmap *altmap)
+void __ref arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
 {
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;

arch/powerpc/platforms/pseries/hotplug-memory.c

···
 {
 	unsigned long block_sz, start_pfn;
 	int sections_per_block;
-	int i, nid;
+	int i;
 
 	start_pfn = base >> PAGE_SHIFT;
 
···
 
 	block_sz = pseries_memory_block_size();
 	sections_per_block = block_sz / MIN_MEMORY_BLOCK_SIZE;
-	nid = memory_add_physaddr_to_nid(base);
 
 	for (i = 0; i < sections_per_block; i++) {
-		__remove_memory(nid, base, MIN_MEMORY_BLOCK_SIZE);
+		__remove_memory(base, MIN_MEMORY_BLOCK_SIZE);
 		base += MIN_MEMORY_BLOCK_SIZE;
 	}
 
···
 
 	block_sz = pseries_memory_block_size();
 
-	__remove_memory(mem_block->nid, lmb->base_addr, block_sz);
+	__remove_memory(lmb->base_addr, block_sz);
 	put_device(&mem_block->dev);
 
 	/* Update memory regions for memory remove */
···
 
 	rc = dlpar_online_lmb(lmb);
 	if (rc) {
-		__remove_memory(nid, lmb->base_addr, block_sz);
+		__remove_memory(lmb->base_addr, block_sz);
 		invalidate_lmb_associativity_index(lmb);
 	} else {
 		lmb->flags |= DRCONF_MEM_ASSIGNED;

arch/riscv/Kconfig

···
 	select GENERIC_EARLY_IOREMAP
 	select GENERIC_GETTIMEOFDAY if HAVE_GENERIC_VDSO
 	select GENERIC_IDLE_POLL_SETUP
-	select GENERIC_IOREMAP
+	select GENERIC_IOREMAP if MMU
 	select GENERIC_IRQ_MULTI_HANDLER
 	select GENERIC_IRQ_SHOW
 	select GENERIC_IRQ_SHOW_LEVEL

arch/riscv/kernel/traps.c

···
 }
 #endif /* CONFIG_GENERIC_BUG */
 
-/* stvec & scratch is already set from head.S */
-void __init trap_init(void)
-{
-}
-
 #ifdef CONFIG_VMAP_STACK
 static DEFINE_PER_CPU(unsigned long [OVERFLOW_STACK_SIZE/sizeof(long)],
 		overflow_stack)__aligned(16);

arch/s390/mm/init.c

···
 	return rc;
 }
 
-void arch_remove_memory(int nid, u64 start, u64 size,
-			struct vmem_altmap *altmap)
+void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
 {
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;

arch/sh/mm/init.c

···
 	return ret;
 }
 
-void arch_remove_memory(int nid, u64 start, u64 size,
-			struct vmem_altmap *altmap)
+void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
 {
 	unsigned long start_pfn = PFN_DOWN(start);
 	unsigned long nr_pages = size >> PAGE_SHIFT;

arch/um/kernel/trap.c

···
 {
 	do_IRQ(WINCH_IRQ, regs);
 }
-
-void trap_init(void)
-{
-}

arch/x86/configs/i386_defconfig

···
 CONFIG_8139TOO=y
 # CONFIG_8139TOO_PIO is not set
 CONFIG_R8169=y
-CONFIG_INPUT_POLLDEV=y
 CONFIG_INPUT_EVDEV=y
 CONFIG_INPUT_JOYSTICK=y
 CONFIG_INPUT_TABLET=y

arch/x86/configs/x86_64_defconfig

···
 CONFIG_FORCEDETH=y
 CONFIG_8139TOO=y
 CONFIG_R8169=y
-CONFIG_INPUT_POLLDEV=y
 CONFIG_INPUT_EVDEV=y
 CONFIG_INPUT_JOYSTICK=y
 CONFIG_INPUT_TABLET=y

arch/x86/mm/init_32.c

···
 	return __add_pages(nid, start_pfn, nr_pages, params);
 }
 
-void arch_remove_memory(int nid, u64 start, u64 size,
-			struct vmem_altmap *altmap)
+void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
 {
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;

arch/x86/mm/init_64.c

···
 	remove_pagetable(start, end, true, NULL);
 }
 
-void __ref arch_remove_memory(int nid, u64 start, u64 size,
-			      struct vmem_altmap *altmap)
+void __ref arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap)
 {
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;

drivers/acpi/acpi_memhotplug.c

···
 struct acpi_memory_device {
 	struct acpi_device *device;
 	struct list_head res_list;
+	int mgid;
 };
 
 static acpi_status
···
 static int acpi_memory_enable_device(struct acpi_memory_device *mem_device)
 {
 	acpi_handle handle = mem_device->device->handle;
+	mhp_t mhp_flags = MHP_NID_IS_MGID;
 	int result, num_enabled = 0;
 	struct acpi_memory_info *info;
-	mhp_t mhp_flags = MHP_NONE;
-	int node;
+	u64 total_length = 0;
+	int node, mgid;
 
 	node = acpi_get_node(handle);
+
+	list_for_each_entry(info, &mem_device->res_list, list) {
+		if (!info->length)
+			continue;
+		/* We want a single node for the whole memory group */
+		if (node < 0)
+			node = memory_add_physaddr_to_nid(info->start_addr);
+		total_length += info->length;
+	}
+
+	if (!total_length) {
+		dev_err(&mem_device->device->dev, "device is empty\n");
+		return -EINVAL;
+	}
+
+	mgid = memory_group_register_static(node, PFN_UP(total_length));
+	if (mgid < 0)
+		return mgid;
+	mem_device->mgid = mgid;
+
 	/*
 	 * Tell the VM there is more memory here...
 	 * Note: Assume that this function returns zero on success
···
 	 * (i.e. memory-hot-remove function)
 	 */
 	list_for_each_entry(info, &mem_device->res_list, list) {
-		if (info->enabled) { /* just sanity check...*/
-			num_enabled++;
-			continue;
-		}
 		/*
 		 * If the memory block size is zero, please ignore it.
 		 * Don't try to do the following memory hotplug flowchart.
 		 */
 		if (!info->length)
 			continue;
-		if (node < 0)
-			node = memory_add_physaddr_to_nid(info->start_addr);
 
 		if (mhp_supports_memmap_on_memory(info->length))
 			mhp_flags |= MHP_MEMMAP_ON_MEMORY;
-		result = __add_memory(node, info->start_addr, info->length,
+		result = __add_memory(mgid, info->start_addr, info->length,
 				      mhp_flags);
 
 		/*
···
 
 static void acpi_memory_remove_memory(struct acpi_memory_device *mem_device)
 {
-	acpi_handle handle = mem_device->device->handle;
 	struct acpi_memory_info *info, *n;
-	int nid = acpi_get_node(handle);
 
 	list_for_each_entry_safe(info, n, &mem_device->res_list, list) {
 		if (!info->enabled)
 			continue;
 
-		if (nid == NUMA_NO_NODE)
-			nid = memory_add_physaddr_to_nid(info->start_addr);
-
 		acpi_unbind_memory_blocks(info);
-		__remove_memory(nid, info->start_addr, info->length);
+		__remove_memory(info->start_addr, info->length);
 		list_del(&info->list);
 		kfree(info);
 	}
···
 {
 	if (!mem_device)
 		return;
+
+	/* In case we succeeded adding *some* memory, unregistering fails. */
+	if (mem_device->mgid >= 0)
+		memory_group_unregister(mem_device->mgid);
 
 	acpi_memory_free_device_resources(mem_device);
 	mem_device->device->driver_data = NULL;
···
 
 	INIT_LIST_HEAD(&mem_device->res_list);
 	mem_device->device = device;
+	mem_device->mgid = -1;
 	sprintf(acpi_device_name(device), "%s", ACPI_MEMORY_DEVICE_NAME);
 	sprintf(acpi_device_class(device), "%s", ACPI_MEMORY_DEVICE_CLASS);
 	device->driver_data = mem_device;

drivers/base/memory.c

···
  */
 static DEFINE_XARRAY(memory_blocks);
 
+/*
+ * Memory groups, indexed by memory group id (mgid).
+ */
+static DEFINE_XARRAY_FLAGS(memory_groups, XA_FLAGS_ALLOC);
+#define MEMORY_GROUP_MARK_DYNAMIC	XA_MARK_1
+
 static BLOCKING_NOTIFIER_HEAD(memory_chain);
 
 int register_memory_notifier(struct notifier_block *nb)
···
 	struct zone *zone;
 	int ret;
 
-	zone = zone_for_pfn_range(mem->online_type, mem->nid, start_pfn, nr_pages);
+	zone = zone_for_pfn_range(mem->online_type, mem->nid, mem->group,
+				  start_pfn, nr_pages);
 
 	/*
 	 * Although vmemmap pages have a different lifecycle than the pages
···
 	}
 
 	ret = online_pages(start_pfn + nr_vmemmap_pages,
-			   nr_pages - nr_vmemmap_pages, zone);
+			   nr_pages - nr_vmemmap_pages, zone, mem->group);
 	if (ret) {
 		if (nr_vmemmap_pages)
 			mhp_deinit_memmap_on_memory(start_pfn, nr_vmemmap_pages);
···
 	 * now already properly populated.
 	 */
 	if (nr_vmemmap_pages)
-		adjust_present_page_count(zone, nr_vmemmap_pages);
+		adjust_present_page_count(pfn_to_page(start_pfn), mem->group,
+					  nr_vmemmap_pages);
 
 	return ret;
 }
···
 	unsigned long start_pfn = section_nr_to_pfn(mem->start_section_nr);
 	unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
 	unsigned long nr_vmemmap_pages = mem->nr_vmemmap_pages;
-	struct zone *zone;
 	int ret;
 
 	/*
 	 * Unaccount before offlining, such that unpopulated zone and kthreads
 	 * can properly be torn down in offline_pages().
 	 */
-	if (nr_vmemmap_pages) {
-		zone = page_zone(pfn_to_page(start_pfn));
-		adjust_present_page_count(zone, -nr_vmemmap_pages);
-	}
+	if (nr_vmemmap_pages)
+		adjust_present_page_count(pfn_to_page(start_pfn), mem->group,
+					  -nr_vmemmap_pages);
 
 	ret = offline_pages(start_pfn + nr_vmemmap_pages,
-			    nr_pages - nr_vmemmap_pages);
+			    nr_pages - nr_vmemmap_pages, mem->group);
 	if (ret) {
 		/* offline_pages() failed. Account back. */
 		if (nr_vmemmap_pages)
-			adjust_present_page_count(zone, nr_vmemmap_pages);
+			adjust_present_page_count(pfn_to_page(start_pfn),
+						  mem->group, nr_vmemmap_pages);
 		return ret;
 	}
 
···
 
 #ifdef CONFIG_MEMORY_HOTREMOVE
 static int print_allowed_zone(char *buf, int len, int nid,
+			      struct memory_group *group,
 			      unsigned long start_pfn, unsigned long nr_pages,
 			      int online_type, struct zone *default_zone)
 {
 	struct zone *zone;
 
-	zone = zone_for_pfn_range(online_type, nid, start_pfn, nr_pages);
+	zone = zone_for_pfn_range(online_type, nid, group, start_pfn, nr_pages);
 	if (zone == default_zone)
 		return 0;
 
···
 	struct memory_block *mem = to_memory_block(dev);
 	unsigned long start_pfn = section_nr_to_pfn(mem->start_section_nr);
 	unsigned long nr_pages = PAGES_PER_SECTION * sections_per_block;
+	struct memory_group *group = mem->group;
 	struct zone *default_zone;
+	int nid = mem->nid;
 	int len = 0;
-	int nid;
 
 	/*
 	 * Check the existing zone. Make sure that we do that only on the
···
 		goto out;
 	}
 
-	nid = mem->nid;
-	default_zone = zone_for_pfn_range(MMOP_ONLINE, nid, start_pfn,
-					  nr_pages);
+	default_zone = zone_for_pfn_range(MMOP_ONLINE, nid, group,
+					  start_pfn, nr_pages);
 
 	len += sysfs_emit_at(buf, len, "%s", default_zone->name);
-	len += print_allowed_zone(buf, len, nid, start_pfn, nr_pages,
+	len += print_allowed_zone(buf, len, nid, group, start_pfn, nr_pages,
 				  MMOP_ONLINE_KERNEL, default_zone);
-	len += print_allowed_zone(buf, len, nid, start_pfn, nr_pages,
+	len += print_allowed_zone(buf, len, nid, group, start_pfn, nr_pages,
 				  MMOP_ONLINE_MOVABLE, default_zone);
 out:
 	len += sysfs_emit_at(buf, len, "\n");
···
 }
 
 static int init_memory_block(unsigned long block_id, unsigned long state,
-			     unsigned long nr_vmemmap_pages)
+			     unsigned long nr_vmemmap_pages,
+			     struct memory_group *group)
 {
 	struct memory_block *mem;
 	int ret = 0;
···
 	mem->state = state;
 	mem->nid = NUMA_NO_NODE;
 	mem->nr_vmemmap_pages = nr_vmemmap_pages;
+	INIT_LIST_HEAD(&mem->group_next);
+
+	if (group) {
+		mem->group = group;
+		list_add(&mem->group_next, &group->memory_blocks);
+	}
 
 	ret = register_memory(mem);
 
···
 	if (section_count == 0)
 		return 0;
 	return init_memory_block(memory_block_id(base_section_nr),
-				 MEM_ONLINE, 0);
+				 MEM_ONLINE, 0,  NULL);
 }
 
 static void unregister_memory(struct memory_block *memory)
···
 		return;
 
 	WARN_ON(xa_erase(&memory_blocks, memory->dev.id) == NULL);
+
+	if (memory->group) {
+		list_del(&memory->group_next);
+		memory->group = NULL;
+	}
 
 	/* drop the ref. we got via find_memory_block() */
 	put_device(&memory->dev);
···
  * Called under device_hotplug_lock.
  */
 int create_memory_block_devices(unsigned long start, unsigned long size,
-				unsigned long vmemmap_pages)
+				unsigned long vmemmap_pages,
+				struct memory_group *group)
 {
 	const unsigned long start_block_id = pfn_to_block_id(PFN_DOWN(start));
 	unsigned long end_block_id = pfn_to_block_id(PFN_DOWN(start + size));
···
 		return -EINVAL;
 
 	for (block_id = start_block_id; block_id != end_block_id; block_id++) {
-		ret = init_memory_block(block_id, MEM_OFFLINE, vmemmap_pages);
+		ret = init_memory_block(block_id, MEM_OFFLINE, vmemmap_pages,
+					group);
 		if (ret)
 			break;
 	}
···
 
 	return bus_for_each_dev(&memory_subsys, NULL, &cb_data,
 				for_each_memory_block_cb);
+}
+
+/*
+ * This is an internal helper to unify allocation and initialization of
+ * memory groups. Note that the passed memory group will be copied to a
+ * dynamically allocated memory group. After this call, the passed
+ * memory group should no longer be used.
+ */
+static int memory_group_register(struct memory_group group)
+{
+	struct memory_group *new_group;
+	uint32_t mgid;
+	int ret;
+
+	if (!node_possible(group.nid))
+		return -EINVAL;
+
+	new_group = kzalloc(sizeof(group), GFP_KERNEL);
+	if (!new_group)
+		return -ENOMEM;
+	*new_group = group;
+	INIT_LIST_HEAD(&new_group->memory_blocks);
+
+	ret = xa_alloc(&memory_groups, &mgid, new_group, xa_limit_31b,
+		       GFP_KERNEL);
+	if (ret) {
+		kfree(new_group);
+		return ret;
+	} else if (group.is_dynamic) {
+		xa_set_mark(&memory_groups, mgid, MEMORY_GROUP_MARK_DYNAMIC);
+	}
+	return mgid;
+}
+
+/**
+ * memory_group_register_static() - Register a static memory group.
+ * @nid: The node id.
+ * @max_pages: The maximum number of pages we'll have in this static memory
+ *	       group.
+ *
+ * Register a new static memory group and return the memory group id.
+ * All memory in the group belongs to a single unit, such as a DIMM. All
+ * memory belonging to a static memory group is added in one go to be removed
+ * in one go -- it's static.
+ *
+ * Returns an error if out of memory, if the node id is invalid, if no new
+ * memory groups can be registered, or if max_pages is invalid (0). Otherwise,
+ * returns the new memory group id.
+ */
+int memory_group_register_static(int nid, unsigned long max_pages)
+{
+	struct memory_group group = {
+		.nid = nid,
+		.s = {
+			.max_pages = max_pages,
+		},
+	};
+
+	if (!max_pages)
+		return -EINVAL;
+	return memory_group_register(group);
+}
+EXPORT_SYMBOL_GPL(memory_group_register_static);
+
+/**
+ * memory_group_register_dynamic() - Register a dynamic memory group.
+ * @nid: The node id.
+ * @unit_pages: Unit in pages in which is memory added/removed in this dynamic
+ *		memory group.
+ *
+ * Register a new dynamic memory group and return the memory group id.
+ * Memory within a dynamic memory group is added/removed dynamically
+ * in unit_pages.
+ *
+ * Returns an error if out of memory, if the node id is invalid, if no new
+ * memory groups can be registered, or if unit_pages is invalid (0, not a
+ * power of two, smaller than a single memory block). Otherwise, returns the
+ * new memory group id.
+ */
+int memory_group_register_dynamic(int nid, unsigned long unit_pages)
+{
+	struct memory_group group = {
+		.nid = nid,
+		.is_dynamic = true,
+		.d = {
+			.unit_pages = unit_pages,
+		},
+	};
+
+	if (!unit_pages || !is_power_of_2(unit_pages) ||
+	    unit_pages < PHYS_PFN(memory_block_size_bytes()))
+		return -EINVAL;
+	return memory_group_register(group);
+}
+EXPORT_SYMBOL_GPL(memory_group_register_dynamic);
+
+/**
+ * memory_group_unregister() - Unregister a memory group.
+ * @mgid: the memory group id
+ *
+ * Unregister a memory group. If any memory block still belongs to this
+ * memory group, unregistering will fail.
+ *
+ * Returns -EINVAL if the memory group id is invalid, returns -EBUSY if some
+ * memory blocks still belong to this memory group and returns 0 if
+ * unregistering succeeded.
+ */
+int memory_group_unregister(int mgid)
+{
+	struct memory_group *group;
+
+	if (mgid < 0)
+		return -EINVAL;
+
+	group = xa_load(&memory_groups, mgid);
+	if (!group)
+		return -EINVAL;
+	if (!list_empty(&group->memory_blocks))
+		return -EBUSY;
+	xa_erase(&memory_groups, mgid);
+	kfree(group);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(memory_group_unregister);
+
+/*
+ * This is an internal helper only to be used in core memory hotplug code to
+ * lookup a memory group. We don't care about locking, as we don't expect a
+ * memory group to get unregistered while adding memory to it -- because
+ * the group and the memory is managed by the same driver.
+ */
+struct memory_group *memory_group_find_by_id(int mgid)
+{
+	return xa_load(&memory_groups, mgid);
+}
+
+/*
+ * This is an internal helper only to be used in core memory hotplug code to
+ * walk all dynamic memory groups excluding a given memory group, either
+ * belonging to a specific node, or belonging to any node.
+ */
+int walk_dynamic_memory_groups(int nid, walk_memory_groups_func_t func,
+			       struct memory_group *excluded, void *arg)
+{
+	struct memory_group *group;
+	unsigned long index;
+	int ret = 0;
+
+	xa_for_each_marked(&memory_groups, index, group,
+			   MEMORY_GROUP_MARK_DYNAMIC) {
+		if (group == excluded)
+			continue;
+#ifdef CONFIG_NUMA
+		if (nid != NUMA_NO_NODE && group->nid != nid)
+			continue;
+#endif /* CONFIG_NUMA */
+		ret = func(group, arg);
+		if (ret)
+			break;
+	}
+	return ret;
 }

drivers/base/node.c

···
 #ifdef CONFIG_MEMORY_HOTPLUG_SPARSE
 static int __ref get_nid_for_pfn(unsigned long pfn)
 {
-	if (!pfn_valid_within(pfn))
-		return -1;
 #ifdef CONFIG_DEFERRED_STRUCT_PAGE_INIT
 	if (system_state < SYSTEM_RUNNING)
 		return early_pfn_to_nid(pfn);

drivers/dax/kmem.c

···
 
 struct dax_kmem_data {
 	const char *res_name;
+	int mgid;
 	struct resource *res[];
 };
 
 static int dev_dax_kmem_probe(struct dev_dax *dev_dax)
 {
 	struct device *dev = &dev_dax->dev;
+	unsigned long total_len = 0;
 	struct dax_kmem_data *data;
-	int rc = -ENOMEM;
-	int i, mapped = 0;
+	int i, rc, mapped = 0;
 	int numa_node;
 
 	/*
···
 		return -EINVAL;
 	}
 
-	data = kzalloc(struct_size(data, res, dev_dax->nr_range), GFP_KERNEL);
-	if (!data)
-		return -ENOMEM;
-
-	data->res_name = kstrdup(dev_name(dev), GFP_KERNEL);
-	if (!data->res_name)
-		goto err_res_name;
-
 	for (i = 0; i < dev_dax->nr_range; i++) {
-		struct resource *res;
 		struct range range;
 
 		rc = dax_kmem_range(dev_dax, i, &range);
···
 					i, range.start, range.end);
 			continue;
 		}
+		total_len += range_len(&range);
+	}
+
+	if (!total_len) {
+		dev_warn(dev, "rejecting DAX region without any memory after alignment\n");
+		return -EINVAL;
+	}
+
+	data = kzalloc(struct_size(data, res, dev_dax->nr_range), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	rc = -ENOMEM;
+	data->res_name = kstrdup(dev_name(dev), GFP_KERNEL);
+	if (!data->res_name)
+		goto err_res_name;
+
+	rc = memory_group_register_static(numa_node, total_len);
+	if (rc < 0)
+		goto err_reg_mgid;
+	data->mgid = rc;
+
+	for (i = 0; i < dev_dax->nr_range; i++) {
+		struct resource *res;
+		struct range range;
+
+		rc = dax_kmem_range(dev_dax, i, &range);
+		if (rc)
+			continue;
 
 		/* Region is permanently reserved if hotremove fails. */
 		res = request_mem_region(range.start, range_len(&range), data->res_name);
···
 		 * Ensure that future kexec'd kernels will not treat
 		 * this as RAM automatically.
 		 */
-		rc = add_memory_driver_managed(numa_node, range.start,
-				range_len(&range), kmem_name, MHP_NONE);
+		rc = add_memory_driver_managed(data->mgid, range.start,
+				range_len(&range), kmem_name, MHP_NID_IS_MGID);
 
 		if (rc) {
 			dev_warn(dev, "mapping%d: %#llx-%#llx memory add failed\n",
···
 	return 0;
 
 err_request_mem:
+	memory_group_unregister(data->mgid);
+err_reg_mgid:
 	kfree(data->res_name);
 err_res_name:
 	kfree(data);
···
 		if (rc)
 			continue;
 
-		rc = remove_memory(dev_dax->target_node, range.start,
-				range_len(&range));
+		rc = remove_memory(range.start, range_len(&range));
 		if (rc == 0) {
 			release_resource(data->res[i]);
 			kfree(data->res[i]);
···
 	}
 
 	if (success >= dev_dax->nr_range) {
+		memory_group_unregister(data->mgid);
 		kfree(data->res_name);
 		kfree(data);
 		dev_set_drvdata(dev, NULL);

drivers/devfreq/devfreq.c

···
 #include <linux/hrtimer.h>
 #include <linux/of.h>
 #include <linux/pm_qos.h>
+#include <linux/units.h>
 #include "governor.h"
 
 #define CREATE_TRACE_POINTS
···
 
 #define IS_SUPPORTED_FLAG(f, name) ((f & DEVFREQ_GOV_FLAG_##name) ? true : false)
 #define IS_SUPPORTED_ATTR(f, name) ((f & DEVFREQ_GOV_ATTR_##name) ? true : false)
-#define HZ_PER_KHZ	1000
 
 static struct class *devfreq_class;
 static struct dentry *devfreq_debugfs;

drivers/hwmon/mr75203.c

···
 #include <linux/property.h>
 #include <linux/regmap.h>
 #include <linux/reset.h>
+#include <linux/units.h>
 
 /* PVT Common register */
 #define PVT_IP_CONFIG	0x04
···
 #define CLK_SYNTH_EN		BIT(24)
 #define CLK_SYS_CYCLES_MAX	514
 #define CLK_SYS_CYCLES_MIN	2
-#define HZ_PER_MHZ		1000000L
 
 #define SDIF_DISABLE	0x04
 

drivers/iio/common/hid-sensors/hid-sensor-attributes.c

···
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/time.h>
+#include <linux/units.h>
 
 #include <linux/hid-sensor-hub.h>
 #include <linux/iio/iio.h>
-
-#define HZ_PER_MHZ	1000000L
 
 static struct {
 	u32 usage_id;

drivers/iio/light/as73211.c

···
 #include <linux/module.h>
 #include <linux/mutex.h>
 #include <linux/pm.h>
-
-#define HZ_PER_KHZ 1000
+#include <linux/units.h>
 
 #define AS73211_DRV_NAME "as73211"
 

drivers/media/i2c/ov02a10.c

···
 #include <linux/module.h>
 #include <linux/pm_runtime.h>
 #include <linux/regulator/consumer.h>
+#include <linux/units.h>
 #include <media/media-entity.h>
 #include <media/v4l2-async.h>
 #include <media/v4l2-ctrls.h>
···
 /* Test pattern control */
 #define OV02A10_REG_TEST_PATTERN			0xb6
 
-#define HZ_PER_MHZ					1000000L
 #define OV02A10_LINK_FREQ_390MHZ			(390 * HZ_PER_MHZ)
 #define OV02A10_ECLK_FREQ				(24 * HZ_PER_MHZ)
 

drivers/mtd/nand/raw/intel-nand-controller.c

···
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/types.h>
+#include <linux/units.h>
 #include <asm/unaligned.h>
 
 #define EBU_CLC			0x000
···
 
 #define MAX_CS	2
 
-#define HZ_PER_MHZ	1000000L
 #define USEC_PER_SEC	1000000L
 
 struct ebu_nand_cs {

drivers/phy/st/phy-stm32-usbphyc.c

···
 #include <linux/of_platform.h>
 #include <linux/phy/phy.h>
 #include <linux/reset.h>
+#include <linux/units.h>
 
 #define STM32_USBPHYC_PLL	0x0
 #define STM32_USBPHYC_MISC	0x8
···
 #define PLL_FVCO_MHZ		2880
 #define PLL_INFF_MIN_RATE_HZ	19200000
 #define PLL_INFF_MAX_RATE_HZ	38400000
-#define HZ_PER_MHZ		1000000L
 
 struct pll_params {
 	u8 ndiv;

drivers/thermal/devfreq_cooling.c

···
 #include <linux/pm_opp.h>
 #include <linux/pm_qos.h>
 #include <linux/thermal.h>
+#include <linux/units.h>
 
 #include <trace/events/thermal.h>
 
-#define HZ_PER_KHZ		1000
 #define SCALE_ERROR_MITIGATION	100
 
 /**

drivers/virtio/virtio_mem.c

···
 	 * add_memory_driver_managed().
 	 */
 	const char *resource_name;
+	/* Memory group identification. */
+	int mgid;
 
 	/*
 	 * We don't want to add too much memory if it's not getting onlined,
···
 		addr + size - 1);
 	/* Memory might get onlined immediately. */
 	atomic64_add(size, &vm->offline_size);
-	rc = add_memory_driver_managed(vm->nid, addr, size, vm->resource_name,
-				       MHP_MERGE_RESOURCE);
+	rc = add_memory_driver_managed(vm->mgid, addr, size, vm->resource_name,
+				       MHP_MERGE_RESOURCE | MHP_NID_IS_MGID);
 	if (rc) {
 		atomic64_sub(size, &vm->offline_size);
 		dev_warn(&vm->vdev->dev, "adding memory failed: %d\n", rc);
···
 
 	dev_dbg(&vm->vdev->dev, "removing memory: 0x%llx - 0x%llx\n", addr,
 		addr + size - 1);
-	rc = remove_memory(vm->nid, addr, size);
+	rc = remove_memory(addr, size);
 	if (!rc) {
 		atomic64_sub(size, &vm->offline_size);
 		/*
···
 		"offlining and removing memory: 0x%llx - 0x%llx\n", addr,
 		addr + size - 1);
 
-	rc = offline_and_remove_memory(vm->nid, addr, size);
+	rc = offline_and_remove_memory(addr, size);
 	if (!rc) {
 		atomic64_sub(size, &vm->offline_size);
 		/*
···
 static int virtio_mem_probe(struct virtio_device *vdev)
 {
 	struct virtio_mem *vm;
+	uint64_t unit_pages;
 	int rc;
 
 	BUILD_BUG_ON(sizeof(struct virtio_mem_req) != 24);
···
 	if (rc)
 		goto out_del_vq;
 
+	/* use a single dynamic memory group to cover the whole memory device */
+	if (vm->in_sbm)
+		unit_pages = PHYS_PFN(memory_block_size_bytes());
+	else
+		unit_pages = PHYS_PFN(vm->bbm.bb_size);
+	rc = memory_group_register_dynamic(vm->nid, unit_pages);
+	if (rc < 0)
+		goto out_del_resource;
+	vm->mgid = rc;
+
 	/*
 	 * If we still have memory plugged, we have to unplug all memory first.
 	 * Registering our parent resource makes sure that this memory isn't
···
 	vm->memory_notifier.notifier_call = virtio_mem_memory_notifier_cb;
 	rc = register_memory_notifier(&vm->memory_notifier);
 	if (rc)
-		goto out_del_resource;
+		goto out_unreg_group;
 	rc = register_virtio_mem_device(vm);
 	if (rc)
 		goto out_unreg_mem;
···
 	return 0;
 out_unreg_mem:
 	unregister_memory_notifier(&vm->memory_notifier);
+out_unreg_group:
+	memory_group_unregister(vm->mgid);
 out_del_resource:
 	virtio_mem_delete_resource(vm);
 out_del_vq:
···
 	} else {
 		virtio_mem_delete_resource(vm);
 		kfree_const(vm->resource_name);
+		memory_group_unregister(vm->mgid);
 	}
 
 	/* remove all tracking data - no locking needed */

fs/coredump.c

···
 		 * filesystem.
 		 */
 		mnt_userns = file_mnt_user_ns(cprm.file);
-		if (!uid_eq(i_uid_into_mnt(mnt_userns, inode), current_fsuid()))
+		if (!uid_eq(i_uid_into_mnt(mnt_userns, inode),
+			    current_fsuid())) {
+			pr_info_ratelimited("Core dump to %s aborted: cannot preserve file owner\n",
+					    cn.corename);
 			goto close_fail;
-		if ((inode->i_mode & 0677) != 0600)
+		}
+		if ((inode->i_mode & 0677) != 0600) {
+			pr_info_ratelimited("Core dump to %s aborted: cannot preserve file permissions\n",
+					    cn.corename);
 			goto close_fail;
+		}
 		if (!(cprm.file->f_mode & FMODE_CAN_WRITE))
 			goto close_fail;
 		if (do_truncate(mnt_userns, cprm.file->f_path.dentry,
···
 
 	mmap_write_unlock(mm);
 
-	if (WARN_ON(i != *vma_count))
+	if (WARN_ON(i != *vma_count)) {
+		kvfree(*vma_meta);
 		return -EFAULT;
+	}
 
 	*vma_data_size_ptr = vma_data_size;
 	return 0;

fs/eventpoll.c

···
 	 */
 	call_rcu(&epi->rcu, epi_rcu_free);
 
-	atomic_long_dec(&ep->user->epoll_watches);
+	percpu_counter_dec(&ep->user->epoll_watches);
 
 	return 0;
 }
···
 {
 	int error, pwake = 0;
 	__poll_t revents;
-	long user_watches;
 	struct epitem *epi;
 	struct ep_pqueue epq;
 	struct eventpoll *tep = NULL;
···
 
 	lockdep_assert_irqs_enabled();
 
-	user_watches = atomic_long_read(&ep->user->epoll_watches);
-	if (unlikely(user_watches >= max_user_watches))
+	if (unlikely(percpu_counter_compare(&ep->user->epoll_watches,
+					    max_user_watches) >= 0))
 		return -ENOSPC;
-	if (!(epi = kmem_cache_zalloc(epi_cache, GFP_KERNEL)))
+	percpu_counter_inc(&ep->user->epoll_watches);
+
+	if (!(epi = kmem_cache_zalloc(epi_cache, GFP_KERNEL))) {
+		percpu_counter_dec(&ep->user->epoll_watches);
 		return -ENOMEM;
+	}
 
 	/* Item initialization follow here ... */
 	INIT_LIST_HEAD(&epi->rdllink);
···
 		mutex_lock_nested(&tep->mtx, 1);
 	/* Add the current item to the list of active epoll hook for this file */
 	if (unlikely(attach_epitem(tfile, epi) < 0)) {
-		kmem_cache_free(epi_cache, epi);
 		if (tep)
 			mutex_unlock(&tep->mtx);
+		kmem_cache_free(epi_cache, epi);
+		percpu_counter_dec(&ep->user->epoll_watches);
 		return -ENOMEM;
 	}
 
 	if (full_check && !tep)
 		list_file(tfile);
-
-	atomic_long_inc(&ep->user->epoll_watches);
 
 	/*
 	 * Add the current item to the RB tree. All RB tree operations are

fs/nilfs2/sysfs.c

···
 #define NILFS_DEV_INT_GROUP_TYPE(name, parent_name) \
 static void nilfs_##name##_attr_release(struct kobject *kobj) \
 { \
-	struct nilfs_sysfs_##parent_name##_subgroups *subgroups; \
-	struct the_nilfs *nilfs = container_of(kobj->parent, \
-						struct the_nilfs, \
-						ns_##parent_name##_kobj); \
-	subgroups = nilfs->ns_##parent_name##_subgroups; \
+	struct nilfs_sysfs_##parent_name##_subgroups *subgroups = container_of(kobj, \
+						struct nilfs_sysfs_##parent_name##_subgroups, \
+						sg_##name##_kobj); \
 	complete(&subgroups->sg_##name##_kobj_unregister); \
 } \
 static struct kobj_type nilfs_##name##_ktype = { \
···
 	err = kobject_init_and_add(kobj, &nilfs_##name##_ktype, parent, \
 				    #name); \
 	if (err) \
-		return err; \
-	return 0; \
+		kobject_put(kobj); \
+	return err; \
 } \
 static void nilfs_sysfs_delete_##name##_group(struct the_nilfs *nilfs) \
 { \
-	kobject_del(&nilfs->ns_##parent_name##_subgroups->sg_##name##_kobj); \
+	kobject_put(&nilfs->ns_##parent_name##_subgroups->sg_##name##_kobj); \
 }
 
 /************************************************************************
···
 	}
 
 	if (err)
-		return err;
+		kobject_put(&root->snapshot_kobj);
 
-	return 0;
+	return err;
 }
 
 void nilfs_sysfs_delete_snapshot_group(struct nilfs_root *root)
 {
-	kobject_del(&root->snapshot_kobj);
+	kobject_put(&root->snapshot_kobj);
 }
 
 /************************************************************************
···
 	err = kobject_init_and_add(&nilfs->ns_dev_kobj, &nilfs_dev_ktype, NULL,
 				    "%s", sb->s_id);
 	if (err)
-		goto free_dev_subgroups;
+		goto cleanup_dev_kobject;
 
 	err = nilfs_sysfs_create_mounted_snapshots_group(nilfs);
 	if (err)
···
 	nilfs_sysfs_delete_mounted_snapshots_group(nilfs);
 
 cleanup_dev_kobject:
-	kobject_del(&nilfs->ns_dev_kobj);
-
-free_dev_subgroups:
+	kobject_put(&nilfs->ns_dev_kobj);
 	kfree(nilfs->ns_dev_subgroups);
 
 failed_create_device_group:

fs/nilfs2/the_nilfs.c

···
 
 void nilfs_put_root(struct nilfs_root *root)
 {
-	if (refcount_dec_and_test(&root->count)) {
-		struct the_nilfs *nilfs = root->nilfs;
+	struct the_nilfs *nilfs = root->nilfs;
 
-		nilfs_sysfs_delete_snapshot_group(root);
-
-		spin_lock(&nilfs->ns_cptree_lock);
+	if (refcount_dec_and_lock(&root->count, &nilfs->ns_cptree_lock)) {
 		rb_erase(&root->rb_node, &nilfs->ns_cptree);
 		spin_unlock(&nilfs->ns_cptree_lock);
+
+		nilfs_sysfs_delete_snapshot_group(root);
 		iput(root->ifile);
 
 		kfree(root);

fs/proc/array.c

···
 
 void proc_task_name(struct seq_file *m, struct task_struct *p, bool escape)
 {
-	char *buf;
-	size_t size;
 	char tcomm[64];
-	int ret;
 
 	if (p->flags & PF_WQ_WORKER)
 		wq_worker_comm(tcomm, sizeof(tcomm), p);
 	else
 		__get_task_comm(tcomm, sizeof(tcomm), p);
 
-	size = seq_get_buf(m, &buf);
-	if (escape) {
-		ret = string_escape_str(tcomm, buf, size,
-					ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\");
-		if (ret >= size)
-			ret = -1;
-	} else {
-		ret = strscpy(buf, tcomm, size);
-	}
-
-	seq_commit(m, ret);
+	if (escape)
+		seq_escape_str(m, tcomm, ESCAPE_SPACE | ESCAPE_SPECIAL, "\n\\");
+	else
+		seq_printf(m, "%.64s", tcomm);
 }
 
 /*

fs/proc/base.c

···
 #include <linux/posix-timers.h>
 #include <linux/time_namespace.h>
 #include <linux/resctrl.h>
+#include <linux/cn_proc.h>
 #include <trace/events/oom.h>
 #include "internal.h"
 #include "fd.h"
···
 	if (!p)
 		return -ESRCH;
 
-	if (same_thread_group(current, p))
+	if (same_thread_group(current, p)) {
 		set_task_comm(p, buffer);
+		proc_comm_connector(p);
+	}
 	else
 		count = -EINVAL;
 

include/asm-generic/early_ioremap.h

···
 extern void early_iounmap(void __iomem *addr, unsigned long size);
 extern void early_memunmap(void *addr, unsigned long size);
 
-/*
- * Weak function called by early_ioremap_reset(). It does nothing, but
- * architectures may provide their own version to do any needed cleanups.
- */
-extern void early_ioremap_shutdown(void);
-
 #if defined(CONFIG_GENERIC_EARLY_IOREMAP) && defined(CONFIG_MMU)
 /* Arch-specific initialization */
 extern void early_ioremap_init(void);

include/linux/damon.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * DAMON api
+ *
+ * Author: SeongJae Park <[e-mail]>
+ */
+
+#ifndef _DAMON_H_
+#define _DAMON_H_
+
+#include <linux/mutex.h>
+#include <linux/time64.h>
+#include <linux/types.h>
+
+/* Minimal region size.  Every damon_region is aligned by this. */
+#define DAMON_MIN_REGION	PAGE_SIZE
+
+/**
+ * struct damon_addr_range - Represents an address region of [@start, @end).
+ * @start:	Start address of the region (inclusive).
+ * @end:	End address of the region (exclusive).
+ */
+struct damon_addr_range {
+	unsigned long start;
+	unsigned long end;
+};
+
+/**
+ * struct damon_region - Represents a monitoring target region.
+ * @ar:			The address range of the region.
+ * @sampling_addr:	Address of the sample for the next access check.
+ * @nr_accesses:	Access frequency of this region.
+ * @list:		List head for siblings.
+ */
+struct damon_region {
+	struct damon_addr_range ar;
+	unsigned long sampling_addr;
+	unsigned int nr_accesses;
+	struct list_head list;
+};
+
+/**
+ * struct damon_target - Represents a monitoring target.
+ * @id:			Unique identifier for this target.
+ * @nr_regions:		Number of monitoring target regions of this target.
+ * @regions_list:	Head of the monitoring target regions of this target.
+ * @list:		List head for siblings.
+ *
+ * Each monitoring context could have multiple targets.  For example, a context
+ * for virtual memory address spaces could have multiple target processes.  The
+ * @id of each target should be unique among the targets of the context.  For
+ * example, in the virtual address monitoring context, it could be a pidfd or
+ * an address of an mm_struct.
+ */
+struct damon_target {
+	unsigned long id;
+	unsigned int nr_regions;
+	struct list_head regions_list;
+	struct list_head list;
+};
+
+struct damon_ctx;
+
+/**
+ * struct damon_primitive	Monitoring primitives for given use cases.
+ *
+ * @init:			Initialize primitive-internal data structures.
+ * @update:			Update primitive-internal data structures.
+ * @prepare_access_checks:	Prepare next access check of target regions.
+ * @check_accesses:		Check the accesses to target regions.
+ * @reset_aggregated:		Reset aggregated accesses monitoring results.
+ * @target_valid:		Determine if the target is valid.
+ * @cleanup:			Clean up the context.
+ *
+ * DAMON can be extended for various address spaces and usages.  For this,
+ * users should register the low level primitives for their target address
+ * space and usecase via the &damon_ctx.primitive.  Then, the monitoring thread
+ * (&damon_ctx.kdamond) calls @init and @prepare_access_checks before starting
+ * the monitoring, @update after each &damon_ctx.primitive_update_interval, and
+ * @check_accesses, @target_valid and @prepare_access_checks after each
+ * &damon_ctx.sample_interval.  Finally, @reset_aggregated is called after each
+ * &damon_ctx.aggr_interval.
+ *
+ * @init should initialize primitive-internal data structures.  For example,
+ * this could be used to construct proper monitoring target regions and link
+ * those to @damon_ctx.adaptive_targets.
+ * @update should update the primitive-internal data structures.  For example,
+ * this could be used to update monitoring target regions for current status.
+ * @prepare_access_checks should manipulate the monitoring regions to be
+ * prepared for the next access check.
+ * @check_accesses should check the accesses to each region that made after the
+ * last preparation and update the number of observed accesses of each region.
+ * It should also return max number of observed accesses that made as a result
+ * of its update.  The value will be used for regions adjustment threshold.
+ * @reset_aggregated should reset the access monitoring results that aggregated
+ * by @check_accesses.
+ * @target_valid should check whether the target is still valid for the
+ * monitoring.
+ * @cleanup is called from @kdamond just before its termination.
+ */
+struct damon_primitive {
+	void (*init)(struct damon_ctx *context);
+	void (*update)(struct damon_ctx *context);
+	void (*prepare_access_checks)(struct damon_ctx *context);
+	unsigned int (*check_accesses)(struct damon_ctx *context);
+	void (*reset_aggregated)(struct damon_ctx *context);
+	bool (*target_valid)(void *target);
+	void (*cleanup)(struct damon_ctx *context);
+};
+
+/*
+ * struct damon_callback	Monitoring events notification callbacks.
+ *
+ * @before_start:	Called before starting the monitoring.
+ * @after_sampling:	Called after each sampling.
+ * @after_aggregation:	Called after each aggregation.
+ * @before_terminate:	Called before terminating the monitoring.
+ * @private:		User private data.
+ *
+ * The monitoring thread (&damon_ctx.kdamond) calls @before_start and
+ * @before_terminate just before starting and finishing the monitoring,
+ * respectively.  Therefore, those are good places for installing and cleaning
+ * @private.
+ *
+ * The monitoring thread calls @after_sampling and @after_aggregation for each
+ * of the sampling intervals and aggregation intervals, respectively.
+ * Therefore, users can safely access the monitoring results without additional
+ * protection.  For the reason, users are recommended to use these callback for
+ * the accesses to the results.
+ *
+ * If any callback returns non-zero, monitoring stops.
+ */
+struct damon_callback {
+	void *private;
+
+	int (*before_start)(struct damon_ctx *context);
+	int (*after_sampling)(struct damon_ctx *context);
+	int (*after_aggregation)(struct damon_ctx *context);
+	int (*before_terminate)(struct damon_ctx *context);
+};
+
+/**
+ * struct damon_ctx - Represents a context for each monitoring.  This is the
+ * main interface that allows users to set the attributes and get the results
+ * of the monitoring.
+ *
+ * @sample_interval:		The time between access samplings.
+ * @aggr_interval:		The time between monitor results aggregations.
+ * @primitive_update_interval:	The time between monitoring primitive updates.
+ *
+ * For each @sample_interval, DAMON checks whether each region is accessed or
+ * not.  It aggregates and keeps the access information (number of accesses to
+ * each region) for @aggr_interval time.  DAMON also checks whether the target
+ * memory regions need update (e.g., by ``mmap()`` calls from the application,
+ * in case of virtual memory monitoring) and applies the changes for each
+ * @primitive_update_interval.  All time intervals are in micro-seconds.
+ * Please refer to &struct damon_primitive and &struct damon_callback for more
+ * detail.
+ *
+ * @kdamond:		Kernel thread who does the monitoring.
+ * @kdamond_stop:	Notifies whether kdamond should stop.
+ * @kdamond_lock:	Mutex for the synchronizations with @kdamond.
+ *
+ * For each monitoring context, one kernel thread for the monitoring is
+ * created.  The pointer to the thread is stored in @kdamond.
+ *
+ * Once started, the monitoring thread runs until explicitly required to be
+ * terminated or every monitoring target is invalid.  The validity of the
+ * targets is checked via the &damon_primitive.target_valid of @primitive.  The
+ * termination can also be explicitly requested by writing non-zero to
+ * @kdamond_stop.  The thread sets @kdamond to NULL when it terminates.
+ * Therefore, users can know whether the monitoring is ongoing or terminated by
+ * reading @kdamond.  Reads and writes to @kdamond and @kdamond_stop from
+ * outside of the monitoring thread must be protected by @kdamond_lock.
+ *
+ * Note that the monitoring thread protects only @kdamond and @kdamond_stop via
+ * @kdamond_lock.  Accesses to other fields must be protected by themselves.
+ *
+ * @primitive:	Set of monitoring primitives for given use cases.
+ * @callback:	Set of callbacks for monitoring events notifications.
+ *
+ * @min_nr_regions:	The minimum number of adaptive monitoring regions.
+ * @max_nr_regions:	The maximum number of adaptive monitoring regions.
+ * @adaptive_targets:	Head of monitoring targets (&damon_target) list.
+ */
+struct damon_ctx {
+	unsigned long sample_interval;
+	unsigned long aggr_interval;
+	unsigned long primitive_update_interval;
+
+/* private: internal use only */
+	struct timespec64 last_aggregation;
+	struct timespec64 last_primitive_update;
+
+/* public: */
+	struct task_struct *kdamond;
+	bool kdamond_stop;
+	struct mutex kdamond_lock;
+
+	struct damon_primitive primitive;
+	struct damon_callback callback;
+
+	unsigned long min_nr_regions;
+	unsigned long max_nr_regions;
+	struct list_head adaptive_targets;
+};
+
+#define damon_next_region(r) \
+	(container_of(r->list.next, struct damon_region, list))
+
+#define damon_prev_region(r) \
+	(container_of(r->list.prev, struct damon_region, list))
+
+#define damon_for_each_region(r, t) \
+	list_for_each_entry(r, &t->regions_list, list)
+
+#define damon_for_each_region_safe(r, next, t) \
+	list_for_each_entry_safe(r, next, &t->regions_list, list)
+
+#define damon_for_each_target(t, ctx) \
+	list_for_each_entry(t, &(ctx)->adaptive_targets, list)
+
+#define damon_for_each_target_safe(t, next, ctx)	\
+	list_for_each_entry_safe(t, next, &(ctx)->adaptive_targets, list)
+
+#ifdef CONFIG_DAMON
+
+struct damon_region *damon_new_region(unsigned long start, unsigned long end);
+inline void damon_insert_region(struct damon_region *r,
+		struct damon_region *prev, struct damon_region *next,
+		struct damon_target *t);
+void damon_add_region(struct damon_region *r, struct damon_target *t);
+void damon_destroy_region(struct damon_region *r, struct damon_target *t);
+
+struct damon_target *damon_new_target(unsigned long id);
+void damon_add_target(struct damon_ctx *ctx, struct damon_target *t);
+void damon_free_target(struct damon_target *t);
+void damon_destroy_target(struct damon_target *t);
+unsigned int damon_nr_regions(struct damon_target *t);
+
+struct damon_ctx *damon_new_ctx(void);
+void damon_destroy_ctx(struct damon_ctx *ctx);
+int damon_set_targets(struct damon_ctx *ctx,
+		unsigned long *ids, ssize_t nr_ids);
+int damon_set_attrs(struct damon_ctx *ctx, unsigned long sample_int,
+		unsigned long aggr_int, unsigned long primitive_upd_int,
+		unsigned long min_nr_reg, unsigned long max_nr_reg);
+int damon_nr_running_ctxs(void);
+
+int damon_start(struct damon_ctx **ctxs, int nr_ctxs);
+int damon_stop(struct damon_ctx **ctxs, int nr_ctxs);
+
+#endif	/* CONFIG_DAMON */
+
+#ifdef CONFIG_DAMON_VADDR
+
+/* Monitoring primitives for virtual memory address spaces */
+void damon_va_init(struct damon_ctx *ctx);
+void damon_va_update(struct damon_ctx *ctx);
+void damon_va_prepare_access_checks(struct damon_ctx *ctx);
+unsigned int damon_va_check_accesses(struct damon_ctx *ctx);
+bool damon_va_target_valid(void *t);
+void damon_va_cleanup(struct damon_ctx *ctx);
+void damon_va_set_primitives(struct damon_ctx *ctx);
+
+#endif	/* CONFIG_DAMON_VADDR */
+
+#endif	/* _DAMON_H */

include/linux/highmem-internal.h

···
 
 static inline void *kmap_atomic_prot(struct page *page, pgprot_t prot)
 {
-	preempt_disable();
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		migrate_disable();
+	else
+		preempt_disable();
+
 	pagefault_disable();
 	return __kmap_local_page_prot(page, prot);
 }
···
 
 static inline void *kmap_atomic_pfn(unsigned long pfn)
 {
-	preempt_disable();
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		migrate_disable();
+	else
+		preempt_disable();
+
 	pagefault_disable();
 	return __kmap_local_pfn_prot(pfn, kmap_prot);
 }
···
 {
 	kunmap_local_indexed(addr);
 	pagefault_enable();
-	preempt_enable();
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		migrate_enable();
+	else
+		preempt_enable();
 }
 
 unsigned int __nr_free_highpages(void);
···
 
 static inline void *kmap_atomic(struct page *page)
 {
-	preempt_disable();
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		migrate_disable();
+	else
+		preempt_disable();
 	pagefault_disable();
 	return page_address(page);
 }
···
 	kunmap_flush_on_unmap(addr);
 #endif
 	pagefault_enable();
-	preempt_enable();
+	if (IS_ENABLED(CONFIG_PREEMPT_RT))
+		migrate_enable();
+	else
+		preempt_enable();
 }
 
 static inline unsigned int nr_free_highpages(void) { return 0; }

include/linux/memory.h

···
 
 #define MIN_MEMORY_BLOCK_SIZE     (1UL << SECTION_SIZE_BITS)
 
+/**
+ * struct memory_group - a logical group of memory blocks
+ * @nid: The node id for all memory blocks inside the memory group.
+ * @blocks: List of all memory blocks belonging to this memory group.
+ * @present_kernel_pages: Present (online) memory outside ZONE_MOVABLE of this
+ *			  memory group.
+ * @present_movable_pages: Present (online) memory in ZONE_MOVABLE of this
+ *			   memory group.
+ * @is_dynamic: The memory group type: static vs. dynamic
+ * @s.max_pages: Valid with &memory_group.is_dynamic == false. The maximum
+ *		 number of pages we'll have in this static memory group.
+ * @d.unit_pages: Valid with &memory_group.is_dynamic == true. Unit in pages
+ *		  in which memory is added/removed in this dynamic memory group.
+ *		  This granularity defines the alignment of a unit in physical
+ *		  address space; it has to be at least as big as a single
+ *		  memory block.
+ *
+ * A memory group logically groups memory blocks; each memory block
+ * belongs to at most one memory group. A memory group corresponds to
+ * a memory device, such as a DIMM or a NUMA node, which spans multiple
+ * memory blocks and might even span multiple non-contiguous physical memory
+ * ranges.
+ *
+ * Modification of members after registration is serialized by memory
+ * hot(un)plug code.
+ */
+struct memory_group {
+	int nid;
+	struct list_head memory_blocks;
+	unsigned long present_kernel_pages;
+	unsigned long present_movable_pages;
+	bool is_dynamic;
+	union {
+		struct {
+			unsigned long max_pages;
+		} s;
+		struct {
+			unsigned long unit_pages;
+		} d;
+	};
+};
+
 struct memory_block {
 	unsigned long start_section_nr;
 	unsigned long state;		/* serialized by the dev->lock */
···
 	 * lay at the beginning of the memory block.
 	 */
 	unsigned long nr_vmemmap_pages;
+	struct memory_group *group;	/* group (if any) for this block */
+	struct list_head group_next;	/* next block inside memory group */
 };
 
 int arch_get_memory_phys_device(unsigned long start_pfn);
···
 extern int register_memory_notifier(struct notifier_block *nb);
 extern void unregister_memory_notifier(struct notifier_block *nb);
 int create_memory_block_devices(unsigned long start, unsigned long size,
-				unsigned long vmemmap_pages);
+				unsigned long vmemmap_pages,
+				struct memory_group *group);
 void remove_memory_block_devices(unsigned long start, unsigned long size);
 extern void memory_dev_init(void);
 extern int memory_notify(unsigned long val, void *v);
···
 			      void *arg, walk_memory_blocks_func_t func);
 extern int for_each_memory_block(void *arg, walk_memory_blocks_func_t func);
 #define CONFIG_MEM_BLOCK_SIZE	(PAGES_PER_SECTION<<PAGE_SHIFT)
+
+extern int memory_group_register_static(int nid, unsigned long max_pages);
+extern int memory_group_register_dynamic(int nid, unsigned long unit_pages);
+extern int memory_group_unregister(int mgid);
+struct memory_group *memory_group_find_by_id(int mgid);
+typedef int (*walk_memory_groups_func_t)(struct memory_group *, void *);
+int walk_dynamic_memory_groups(int nid, walk_memory_groups_func_t func,
+			       struct memory_group *excluded, void *arg);
 #endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
 
 #ifdef CONFIG_MEMORY_HOTPLUG

include/linux/memory_hotplug.h

···
 struct pglist_data;
 struct mem_section;
 struct memory_block;
+struct memory_group;
 struct resource;
 struct vmem_altmap;
 
···
  * Only selected architectures support it with SPARSE_VMEMMAP.
  */
 #define MHP_MEMMAP_ON_MEMORY   ((__force mhp_t)BIT(1))
+/*
+ * The nid field specifies a memory group id (mgid) instead. The memory group
+ * implies the node id (nid).
+ */
+#define MHP_NID_IS_MGID		((__force mhp_t)BIT(2))
 
 /*
  * Extended parameters for memory hotplug:
···
 extern int zone_grow_free_lists(struct zone *zone, unsigned long new_nr_pages);
 extern int zone_grow_waitqueues(struct zone *zone, unsigned long nr_pages);
 extern int add_one_highpage(struct page *page, int pfn, int bad_ppro);
-extern void adjust_present_page_count(struct zone *zone, long nr_pages);
+extern void adjust_present_page_count(struct page *page,
+				      struct memory_group *group,
+				      long nr_pages);
 /* VM interface that may be used by firmware interface */
 extern int mhp_init_memmap_on_memory(unsigned long pfn, unsigned long nr_pages,
 				     struct zone *zone);
 extern void mhp_deinit_memmap_on_memory(unsigned long pfn, unsigned long nr_pages);
 extern int online_pages(unsigned long pfn, unsigned long nr_pages,
-			struct zone *zone);
+			struct zone *zone, struct memory_group *group);
 extern struct zone *test_pages_in_a_zone(unsigned long start_pfn,
 					 unsigned long end_pfn);
 extern void __offline_isolated_pages(unsigned long start_pfn,
···
 	return movable_node_enabled;
 }
 
-extern void arch_remove_memory(int nid, u64 start, u64 size,
-			       struct vmem_altmap *altmap);
+extern void arch_remove_memory(u64 start, u64 size, struct vmem_altmap *altmap);
 extern void __remove_pages(unsigned long start_pfn, unsigned long nr_pages,
 			   struct vmem_altmap *altmap);
 
···
 #ifdef CONFIG_MEMORY_HOTREMOVE
 
 extern void try_offline_node(int nid);
-extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
-extern int remove_memory(int nid, u64 start, u64 size);
-extern void __remove_memory(int nid, u64 start, u64 size);
-extern int offline_and_remove_memory(int nid, u64 start, u64 size);
+extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages,
+			 struct memory_group *group);
+extern int remove_memory(u64 start, u64 size);
+extern void __remove_memory(u64 start, u64 size);
+extern int offline_and_remove_memory(u64 start, u64 size);
 
 #else
 static inline void try_offline_node(int nid) {}
 
-static inline int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
+static inline int offline_pages(unsigned long start_pfn, unsigned long nr_pages,
+				struct memory_group *group)
 {
 	return -EINVAL;
 }
 
-static inline int remove_memory(int nid, u64 start, u64 size)
+static inline int remove_memory(u64 start, u64 size)
 {
 	return -EBUSY;
 }
 
-static inline void __remove_memory(int nid, u64 start, u64 size) {}
+static inline void __remove_memory(u64 start, u64 size) {}
 #endif /* CONFIG_MEMORY_HOTREMOVE */
 
 extern void set_zone_contiguous(struct zone *zone);
···
 		unsigned long map_offset, struct vmem_altmap *altmap);
 extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map,
 					  unsigned long pnum);
-extern struct zone *zone_for_pfn_range(int online_type, int nid, unsigned start_pfn,
+extern struct zone *zone_for_pfn_range(int online_type, int nid,
+		struct memory_group *group, unsigned long start_pfn,
 		unsigned long nr_pages);
 extern int arch_create_linear_mapping(int nid, u64 start, u64 size,
 				      struct mhp_params *params);

include/linux/mmzone.h

···
 	 * is calculated as:
 	 *	present_pages = spanned_pages - absent_pages(pages in holes);
 	 *
+	 * present_early_pages is present pages existing within the zone
+	 * located on memory available since early boot, excluding hotplugged
+	 * memory.
+	 *
 	 * managed_pages is present pages managed by the buddy system, which
 	 * is calculated as (reserved_pages includes pages allocated by the
 	 * bootmem allocator):
···
 	atomic_long_t		managed_pages;
 	unsigned long		spanned_pages;
 	unsigned long		present_pages;
+#if defined(CONFIG_MEMORY_HOTPLUG)
+	unsigned long		present_early_pages;
+#endif
 #ifdef CONFIG_CMA
 	unsigned long		cma_pages;
 #endif
···
 #define pfn_in_present_section pfn_valid
 #define subsection_map_init(_pfn, _nr_pages) do {} while (0)
 #endif /* CONFIG_SPARSEMEM */
-
-/*
- * If it is possible to have holes within a MAX_ORDER_NR_PAGES, then we
- * need to check pfn validity within that MAX_ORDER_NR_PAGES block.
- * pfn_valid_within() should be used in this case; we optimise this away
- * when we have no holes within a MAX_ORDER_NR_PAGES block.
- */
-#ifdef CONFIG_HOLES_IN_ZONE
-#define pfn_valid_within(pfn) pfn_valid(pfn)
-#else
-#define pfn_valid_within(pfn) (1)
-#endif
 
 #endif /* !__GENERATING_BOUNDS.H */
 #endif /* !__ASSEMBLY__ */

include/linux/once.h

···
  * out the condition into a nop. DO_ONCE() guarantees type safety of
  * arguments!
  *
- * Not that the following is not equivalent ...
+ * Note that the following is not equivalent ...
  *
  *   DO_ONCE(func, arg);
  *   DO_ONCE(func, arg);

include/linux/page-flags.h

···
 #ifdef CONFIG_MEMORY_FAILURE
 	PG_hwpoison,		/* hardware poisoned page. Don't touch */
 #endif
-#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
+#if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
 	PG_young,
 	PG_idle,
 #endif
···
 	/* Only valid for buddy pages. Used to track pages that are reported */
 	PG_reported = PG_uptodate,
 };
+
+#define PAGEFLAGS_MASK		((1UL << NR_PAGEFLAGS) - 1)
 
 #ifndef __GENERATING_BOUNDS_H
 
···
 #define __PG_HWPOISON 0
 #endif
 
-#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
+#if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
 TESTPAGEFLAG(Young, young, PF_ANY)
 SETPAGEFLAG(Young, young, PF_ANY)
 TESTCLEARFLAG(Young, young, PF_ANY)
···
  * alloc-free cycle to prevent from reusing the page.
  */
 #define PAGE_FLAGS_CHECK_AT_PREP	\
-	(((1UL << NR_PAGEFLAGS) - 1) & ~__PG_HWPOISON)
+	(PAGEFLAGS_MASK & ~__PG_HWPOISON)
 
 #define PAGE_FLAGS_PRIVATE				\
 	(1UL << PG_private | 1UL << PG_private_2)

include/linux/page_ext.h

···
 enum page_ext_flags {
 	PAGE_EXT_OWNER,
 	PAGE_EXT_OWNER_ALLOCATED,
-#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
+#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
 	PAGE_EXT_YOUNG,
 	PAGE_EXT_IDLE,
 #endif

include/linux/page_idle.h

···
 #include <linux/page-flags.h>
 #include <linux/page_ext.h>
 
-#ifdef CONFIG_IDLE_PAGE_TRACKING
+#ifdef CONFIG_PAGE_IDLE_FLAG
 
 #ifdef CONFIG_64BIT
 static inline bool page_is_young(struct page *page)
···
 }
 #endif /* CONFIG_64BIT */
 
-#else /* !CONFIG_IDLE_PAGE_TRACKING */
+#else /* !CONFIG_PAGE_IDLE_FLAG */
 
 static inline bool page_is_young(struct page *page)
 {
···
 {
 }
 
-#endif /* CONFIG_IDLE_PAGE_TRACKING */
+#endif /* CONFIG_PAGE_IDLE_FLAG */
 
 #endif /* _LINUX_MM_PAGE_IDLE_H */

include/linux/pagemap.h

···
  */
 static inline pgoff_t page_to_index(struct page *page)
 {
-	pgoff_t pgoff;
+	struct page *head;
 
 	if (likely(!PageTransTail(page)))
 		return page->index;
 
+	head = compound_head(page);
 	/*
 	 *  We don't initialize ->index for tail pages: calculate based on
 	 *  head page
 	 */
-	pgoff = compound_head(page)->index;
-	pgoff += page - compound_head(page);
-	return pgoff;
+	return head->index + page - head;
 }
 
 extern pgoff_t hugetlb_basepage_index(struct page *page);

include/linux/sched/user.h

···
 
 #include <linux/uidgid.h>
 #include <linux/atomic.h>
+#include <linux/percpu_counter.h>
 #include <linux/refcount.h>
 #include <linux/ratelimit.h>
 
···
 struct user_struct {
 	refcount_t __count;	/* reference count */
 #ifdef CONFIG_EPOLL
-	atomic_long_t epoll_watches; /* The number of file descriptors currently watched */
+	struct percpu_counter epoll_watches; /* The number of file descriptors currently watched */
 #endif
 	unsigned long unix_inflight;	/* How many files in flight in unix sockets */
 	atomic_long_t pipe_bufs;  /* how many pages are allocated in pipe buffers */

include/linux/threads.h

···
  * Define a minimum number of pids per cpu.  Heuristically based
  * on original pid max of 32k for 32 cpus.  Also, increase the
  * minimum settable value for pid_max on the running system based
- * on similar defaults.  See kernel/pid.c:pidmap_init() for details.
+ * on similar defaults.  See kernel/pid.c:pid_idr_init() for details.
  */
 #define PIDS_PER_CPU_DEFAULT	1024
 #define PIDS_PER_CPU_MIN	8

include/linux/units.h

···
 #define PICO	1000000000000ULL
 #define FEMTO	1000000000000000ULL
 
-#define MILLIWATT_PER_WATT	1000L
-#define MICROWATT_PER_MILLIWATT	1000L
-#define MICROWATT_PER_WATT	1000000L
+#define HZ_PER_KHZ		1000UL
+#define KHZ_PER_MHZ		1000UL
+#define HZ_PER_MHZ		1000000UL
+
+#define MILLIWATT_PER_WATT	1000UL
+#define MICROWATT_PER_MILLIWATT	1000UL
+#define MICROWATT_PER_WATT	1000000UL
 
 #define ABSOLUTE_ZERO_MILLICELSIUS -273150
 

include/linux/vmalloc.h

···
 }
 
 #ifdef CONFIG_MMU
-int vmap_range(unsigned long addr, unsigned long end,
-			phys_addr_t phys_addr, pgprot_t prot,
-			unsigned int max_page_shift);
 void vunmap_range(unsigned long addr, unsigned long end);
 static inline void set_vm_flush_reset_perms(void *addr)
 {

include/trace/events/damon.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM damon
+
+#if !defined(_TRACE_DAMON_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_DAMON_H
+
+#include <linux/damon.h>
+#include <linux/types.h>
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(damon_aggregated,
+
+	TP_PROTO(struct damon_target *t, struct damon_region *r,
+		unsigned int nr_regions),
+
+	TP_ARGS(t, r, nr_regions),
+
+	TP_STRUCT__entry(
+		__field(unsigned long, target_id)
+		__field(unsigned int, nr_regions)
+		__field(unsigned long, start)
+		__field(unsigned long, end)
+		__field(unsigned int, nr_accesses)
+	),
+
+	TP_fast_assign(
+		__entry->target_id = t->id;
+		__entry->nr_regions = nr_regions;
+		__entry->start = r->ar.start;
+		__entry->end = r->ar.end;
+		__entry->nr_accesses = r->nr_accesses;
+	),
+
+	TP_printk("target_id=%lu nr_regions=%u %lu-%lu: %u",
+			__entry->target_id, __entry->nr_regions,
+			__entry->start, __entry->end, __entry->nr_accesses)
+);
+
+#endif /* _TRACE_DAMON_H */
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>

include/trace/events/mmflags.h

···
 #define IF_HAVE_PG_HWPOISON(flag,string)
 #endif
 
-#if defined(CONFIG_IDLE_PAGE_TRACKING) && defined(CONFIG_64BIT)
+#if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
 #define IF_HAVE_PG_IDLE(flag,string) ,{1UL << flag, string}
 #else
 #define IF_HAVE_PG_IDLE(flag,string)

include/trace/events/page_ref.h

···
 
 	TP_printk("pfn=0x%lx flags=%s count=%d mapcount=%d mapping=%p mt=%d val=%d",
 		__entry->pfn,
-		show_page_flags(__entry->flags & ((1UL << NR_PAGEFLAGS) - 1)),
+		show_page_flags(__entry->flags & PAGEFLAGS_MASK),
 		__entry->count,
 		__entry->mapcount, __entry->mapping, __entry->mt,
 		__entry->val)
···
 
 	TP_printk("pfn=0x%lx flags=%s count=%d mapcount=%d mapping=%p mt=%d val=%d ret=%d",
 		__entry->pfn,
-		show_page_flags(__entry->flags & ((1UL << NR_PAGEFLAGS) - 1)),
+		show_page_flags(__entry->flags & PAGEFLAGS_MASK),
 		__entry->count,
 		__entry->mapcount, __entry->mapping, __entry->mt,
 		__entry->val, __entry->ret)

init/initramfs.c

···
 #include <linux/mm.h>
 #include <linux/namei.h>
 #include <linux/init_syscalls.h>
+#include <linux/umh.h>
 
 static ssize_t __init xwrite(struct file *file, const char *p, size_t count,
 		loff_t *pos)
···
 {
 	initramfs_cookie = async_schedule_domain(do_populate_rootfs, NULL,
 						 &initramfs_domain);
+	usermodehelper_enable();
 	if (!initramfs_async)
 		wait_for_initramfs();
 	return 0;

init/main.c

···
 
 void __init __weak pgtable_cache_init(void) { }
 
+void __init __weak trap_init(void) { }
+
 bool initcall_debug;
 core_param(initcall_debug, initcall_debug, bool, 0644);
 
···
 	driver_init();
 	init_irq_proc();
 	do_ctors();
-	usermodehelper_enable();
 	do_initcalls();
 }
 

init/noinitramfs.c

···
 #include <linux/kdev_t.h>
 #include <linux/syscalls.h>
 #include <linux/init_syscalls.h>
+#include <linux/umh.h>
 
 /*
  * Create a simple rootfs that is similar to the default initramfs
···
 {
 	int err;
 
+	usermodehelper_enable();
 	err = init_mkdir("/dev", 0755);
 	if (err < 0)
 		goto out;

ipc/util.c

···
 static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,
 					      loff_t *new_pos)
 {
-	struct kern_ipc_perm *ipc;
-	int total, id;
+	struct kern_ipc_perm *ipc = NULL;
+	int max_idx = ipc_get_maxidx(ids);
 
-	total = 0;
-	for (id = 0; id < pos && total < ids->in_use; id++) {
-		ipc = idr_find(&ids->ipcs_idr, id);
-		if (ipc != NULL)
-			total++;
-	}
-
-	ipc = NULL;
-	if (total >= ids->in_use)
+	if (max_idx == -1 || pos > max_idx)
 		goto out;
 
-	for (; pos < ipc_mni; pos++) {
+	for (; pos <= max_idx; pos++) {
 		ipc = idr_find(&ids->ipcs_idr, pos);
 		if (ipc != NULL) {
 			rcu_read_lock();

kernel/acct.c

···
 	/*
 	 * Accounting records are not subject to resource limits.
 	 */
-	flim = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
+	flim = rlimit(RLIMIT_FSIZE);
 	current->signal->rlim[RLIMIT_FSIZE].rlim_cur = RLIM_INFINITY;
 	/* Perform file operations on behalf of whoever enabled accounting */
 	orig_cred = override_creds(file->f_cred);

kernel/fork.c

···
 	rcu_read_unlock();
 	return exe_file;
 }
-EXPORT_SYMBOL(get_mm_exe_file);
 
 /**
  * get_task_exe_file - acquire a reference to the task's executable file
···
 	task_unlock(task);
 	return exe_file;
 }
-EXPORT_SYMBOL(get_task_exe_file);
 
 /**
  * get_task_mm - acquire a reference to the task's mm

kernel/profile.c

···
 #define NR_PROFILE_GRP		(NR_PROFILE_HIT/PROFILE_GRPSZ)
 
 static atomic_t *prof_buffer;
-static unsigned long prof_len, prof_shift;
+static unsigned long prof_len;
+static unsigned short int prof_shift;
 
 int prof_on __read_mostly;
 EXPORT_SYMBOL_GPL(prof_on);
···
 		if (str[strlen(sleepstr)] == ',')
 			str += strlen(sleepstr) + 1;
 		if (get_option(&str, &par))
-			prof_shift = par;
-		pr_info("kernel sleep profiling enabled (shift: %ld)\n",
+			prof_shift = clamp(par, 0, BITS_PER_LONG - 1);
+		pr_info("kernel sleep profiling enabled (shift: %u)\n",
 			prof_shift);
 #else
 		pr_warn("kernel sleep profiling requires CONFIG_SCHEDSTATS\n");
···
 		if (str[strlen(schedstr)] == ',')
 			str += strlen(schedstr) + 1;
 		if (get_option(&str, &par))
-			prof_shift = par;
-		pr_info("kernel schedule profiling enabled (shift: %ld)\n",
+			prof_shift = clamp(par, 0, BITS_PER_LONG - 1);
+		pr_info("kernel schedule profiling enabled (shift: %u)\n",
 			prof_shift);
 	} else if (!strncmp(str, kvmstr, strlen(kvmstr))) {
 		prof_on = KVM_PROFILING;
 		if (str[strlen(kvmstr)] == ',')
 			str += strlen(kvmstr) + 1;
 		if (get_option(&str, &par))
-			prof_shift = par;
-		pr_info("kernel KVM profiling enabled (shift: %ld)\n",
+			prof_shift = clamp(par, 0, BITS_PER_LONG - 1);
+		pr_info("kernel KVM profiling enabled (shift: %u)\n",
 			prof_shift);
 	} else if (get_option(&str, &par)) {
-		prof_shift = par;
+		prof_shift = clamp(par, 0, BITS_PER_LONG - 1);
 		prof_on = CPU_PROFILING;
-		pr_info("kernel profiling enabled (shift: %ld)\n",
+		pr_info("kernel profiling enabled (shift: %u)\n",
 			prof_shift);
 	}
 	return 1;
···
 	unsigned long p = *ppos;
 	ssize_t read;
 	char *pnt;
-	unsigned int sample_step = 1 << prof_shift;
+	unsigned long sample_step = 1UL << prof_shift;
 
 	profile_flip_buffers();
 	if (p >= (prof_len+1)*sizeof(unsigned int))

kernel/sys.c

···
 	error = -EINVAL;
 
 	/*
-	 * @brk should be after @end_data in traditional maps.
-	 */
-	if (prctl_map->start_brk <= prctl_map->end_data ||
-	    prctl_map->brk <= prctl_map->end_data)
-		goto out;
-
-	/*
 	 * Neither we should allow to override limits if they set.
 	 */
 	if (check_data_rlimit(rlimit(RLIMIT_DATA), prctl_map->brk,

kernel/user.c

···
 	return NULL;
 }
 
+static int user_epoll_alloc(struct user_struct *up)
+{
+#ifdef CONFIG_EPOLL
+	return percpu_counter_init(&up->epoll_watches, 0, GFP_KERNEL);
+#else
+	return 0;
+#endif
+}
+
+static void user_epoll_free(struct user_struct *up)
+{
+#ifdef CONFIG_EPOLL
+	percpu_counter_destroy(&up->epoll_watches);
+#endif
+}
+
 /* IRQs are disabled and uidhash_lock is held upon function entry.
  * IRQ state (as stored in flags) is restored and uidhash_lock released
  * upon function exit.
···
 {
 	uid_hash_remove(up);
 	spin_unlock_irqrestore(&uidhash_lock, flags);
+	user_epoll_free(up);
 	kmem_cache_free(uid_cachep, up);
 }
 
···
 
 		new->uid = uid;
 		refcount_set(&new->__count, 1);
+		if (user_epoll_alloc(new)) {
+			kmem_cache_free(uid_cachep, new);
+			return NULL;
+		}
 		ratelimit_state_init(&new->ratelimit, HZ, 100);
 		ratelimit_set_flags(&new->ratelimit, RATELIMIT_MSG_ON_RELEASE);
 
···
 		spin_lock_irq(&uidhash_lock);
 		up = uid_hash_find(uid, hashent);
 		if (up) {
+			user_epoll_free(new);
 			kmem_cache_free(uid_cachep, new);
 		} else {
 			uid_hash_insert(new, hashent);
···
 
 	for(n = 0; n < UIDHASH_SZ; ++n)
 		INIT_HLIST_HEAD(uidhash_table + n);
+
+	if (user_epoll_alloc(&root_user))
+		panic("root_user epoll percpu counter alloc failed");
 
 	/* Insert the root user immediately (init already runs as root) */
 	spin_lock_irq(&uidhash_lock);

lib/Kconfig.debug

···
 	depends on HAVE_HARDLOCKUP_DETECTOR_PERF || HAVE_HARDLOCKUP_DETECTOR_ARCH
 	select LOCKUP_DETECTOR
 	select HARDLOCKUP_DETECTOR_PERF if HAVE_HARDLOCKUP_DETECTOR_PERF
-	select HARDLOCKUP_DETECTOR_ARCH if HAVE_HARDLOCKUP_DETECTOR_ARCH
 	help
 	  Say Y here to enable the kernel to act as a watchdog to detect
 	  hard lockups.
···
 	  If unsure, say N.
 
 config TEST_SORT
-	tristate "Array-based sort test"
-	depends on DEBUG_KERNEL || m
+	tristate "Array-based sort test" if !KUNIT_ALL_TESTS
+	depends on KUNIT
+	default KUNIT_ALL_TESTS
 	help
 	  This option enables the self-test function of 'sort()' at boot,
 	  or at module load time.
···
 
 config RATIONAL_KUNIT_TEST
 	tristate "KUnit test for rational.c" if !KUNIT_ALL_TESTS
-	depends on KUNIT
-	select RATIONAL
+	depends on KUNIT && RATIONAL
 	default KUNIT_ALL_TESTS
 	help
 	  This builds the rational math unit test.

lib/dump_stack.c

···
 }
 
 /**
- * dump_stack - dump the current task information and its stack trace
+ * dump_stack_lvl - dump the current task information and its stack trace
+ * @log_lvl: log level
  *
  * Architectures can override this implementation by implementing its own.
  */

lib/iov_iter.c

···
  * _copy_mc_to_iter - copy to iter with source memory error exception handling
  * @addr: source kernel address
  * @bytes: total transfer length
- * @iter: destination iterator
+ * @i: destination iterator
  *
  * The pmem driver deploys this for the dax operation
  * (dax_copy_to_iter()) for dax reads (bypass page-cache and the
···
  * * ITER_KVEC, ITER_PIPE, and ITER_BVEC can return short copies.
  *   Compare to copy_to_iter() where only ITER_IOVEC attempts might return
  *   a short copy.
+ *
+ * Return: number of bytes copied (may be %0)
  */
 size_t _copy_mc_to_iter(const void *addr, size_t bytes, struct iov_iter *i)
 {
···
  * _copy_from_iter_flushcache - write destination through cpu cache
  * @addr: destination kernel address
  * @bytes: total transfer length
- * @iter: source iterator
+ * @i: source iterator
  *
  * The pmem driver arranges for filesystem-dax to use this facility via
  * dax_copy_from_iter() for ensuring that writes to persistent memory
···
  * all iterator types. The _copy_from_iter_nocache() only attempts to
  * bypass the cache for the ITER_IOVEC case, and on some archs may use
  * instructions that strand dirty-data in the cache.
+ *
+ * Return: number of bytes copied (may be %0)
  */
 size_t _copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
 {

lib/math/Kconfig

···
 	  If unsure, say N.
 
 config RATIONAL
-	bool
+	tristate

lib/math/rational.c

···
 #include <linux/export.h>
 #include <linux/minmax.h>
 #include <linux/limits.h>
+#include <linux/module.h>
 
 /*
  * calculate best rational approximation for a given fraction
···
 }
 
 EXPORT_SYMBOL(rational_best_approximation);
+
+MODULE_LICENSE("GPL v2");

lib/test_printf.c

···
 	bool append = false;
 	int i;
 
-	flags &= BIT(NR_PAGEFLAGS) - 1;
+	flags &= PAGEFLAGS_MASK;
 	if (flags) {
 		page_flags |= flags;
 		snprintf(cmp_buf + size, BUF_SIZE - size, "%s", name);

lib/test_sort.c

···
 // SPDX-License-Identifier: GPL-2.0-only
+
+#include <kunit/test.h>
+
 #include <linux/sort.h>
 #include <linux/slab.h>
 #include <linux/module.h>
···
 
 #define TEST_LEN 1000
 
-static int __init cmpint(const void *a, const void *b)
+static int cmpint(const void *a, const void *b)
 {
 	return *(int *)a - *(int *)b;
 }
 
-static int __init test_sort_init(void)
+static void test_sort(struct kunit *test)
 {
-	int *a, i, r = 1, err = -ENOMEM;
+	int *a, i, r = 1;
 
-	a = kmalloc_array(TEST_LEN, sizeof(*a), GFP_KERNEL);
-	if (!a)
-		return err;
+	a = kunit_kmalloc_array(test, TEST_LEN, sizeof(*a), GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, a);
 
 	for (i = 0; i < TEST_LEN; i++) {
 		r = (r * 725861) % 6599;
···
 
 	sort(a, TEST_LEN, sizeof(*a), cmpint, NULL);
 
-	err = -EINVAL;
 	for (i = 0; i < TEST_LEN-1; i++)
-		if (a[i] > a[i+1]) {
-			pr_err("test has failed\n");
-			goto exit;
-		}
-	err = 0;
-	pr_info("test passed\n");
-exit:
-	kfree(a);
-	return err;
+		KUNIT_ASSERT_LE(test, a[i], a[i + 1]);
 }
 
-static void __exit test_sort_exit(void)
-{
-}
+static struct kunit_case sort_test_cases[] = {
+	KUNIT_CASE(test_sort),
+	{}
+};
 
-module_init(test_sort_init);
-module_exit(test_sort_exit);
+static struct kunit_suite sort_test_suite = {
+	.name = "lib_sort",
+	.test_cases = sort_test_cases,
+};
+
+kunit_test_suites(&sort_test_suite);
 
 MODULE_LICENSE("GPL");

lib/vsprintf.c

···
 static
 char *format_page_flags(char *buf, char *end, unsigned long flags)
 {
-	unsigned long main_flags = flags & (BIT(NR_PAGEFLAGS) - 1);
+	unsigned long main_flags = flags & PAGEFLAGS_MASK;
 	bool append = false;
 	int i;
 

mm/Kconfig

···
 	depends on MMU
 	bool
 
-config HOLES_IN_ZONE
-	bool
-
 # Don't discard allocated memory used to track "memory" and "reserved" memblocks
 # after early boot, so it can still be used to test for validity of memory.
 # Also, memblocks are updated with memory hot(un)plug.
···
 	  lifetime of the system until these kthreads finish the
 	  initialisation.
 
+config PAGE_IDLE_FLAG
+	bool
+	select PAGE_EXTENSION if !64BIT
+	help
+	  This adds PG_idle and PG_young flags to 'struct page'.  PTE Accessed
+	  bit writers can set the state of the bit in the flags so that PTE
+	  Accessed bit readers may avoid disturbance.
+
 config IDLE_PAGE_TRACKING
 	bool "Enable idle page tracking"
 	depends on SYSFS && MMU
-	select PAGE_EXTENSION if !64BIT
+	select PAGE_IDLE_FLAG
 	help
 	  This feature allows to estimate the amount of user pages that have
 	  not been touched during a given period of time. This information can
···
 
 config SECRETMEM
 	def_bool ARCH_HAS_SET_DIRECT_MAP && !EMBEDDED
+
+source "mm/damon/Kconfig"
 
 endmenu

mm/Makefile

···
 mmu-$(CONFIG_MMU)	:= highmem.o memory.o mincore.o \
 			   mlock.o mmap.o mmu_gather.o mprotect.o mremap.o \
 			   msync.o page_vma_mapped.o pagewalk.o \
-			   pgtable-generic.o rmap.o vmalloc.o ioremap.o
+			   pgtable-generic.o rmap.o vmalloc.o
 
 
 ifdef CONFIG_CROSS_MEMORY_ATTACH
···
 obj-$(CONFIG_USERFAULTFD) += userfaultfd.o
 obj-$(CONFIG_IDLE_PAGE_TRACKING) += page_idle.o
 obj-$(CONFIG_DEBUG_PAGE_REF) += debug_page_ref.o
+obj-$(CONFIG_DAMON) += damon/
 obj-$(CONFIG_HARDENED_USERCOPY) += usercopy.o
 obj-$(CONFIG_PERCPU_STATS) += percpu-stats.o
 obj-$(CONFIG_ZONE_DEVICE) += memremap.o
···
 obj-$(CONFIG_PAGE_REPORTING) += page_reporting.o
 obj-$(CONFIG_IO_MAPPING) += io-mapping.o
 obj-$(CONFIG_HAVE_BOOTMEM_INFO_NODE) += bootmem_info.o
+obj-$(CONFIG_GENERIC_IOREMAP) += ioremap.o

mm/compaction.c

···
 	 * is necessary for the block to be a migration source/target.
 	 */
 	do {
-		if (pfn_valid_within(pfn)) {
-			if (check_source && PageLRU(page)) {
-				clear_pageblock_skip(page);
-				return true;
-			}
+		if (check_source && PageLRU(page)) {
+			clear_pageblock_skip(page);
+			return true;
+		}
 
-			if (check_target && PageBuddy(page)) {
-				clear_pageblock_skip(page);
-				return true;
-			}
+		if (check_target && PageBuddy(page)) {
+			clear_pageblock_skip(page);
+			return true;
 		}
 
 		page += (1 << PAGE_ALLOC_COSTLY_ORDER);
···
 			break;
 
 		nr_scanned++;
-		if (!pfn_valid_within(blockpfn))
-			goto isolate_fail;
 
 		/*
 		 * For compound pages such as THP and hugetlbfs, we can save
···
 			cond_resched();
 		}
 
-		if (!pfn_valid_within(low_pfn))
-			goto isolate_fail;
 		nr_scanned++;
 
 		page = pfn_to_page(low_pfn);

mm/damon/Kconfig

···
+# SPDX-License-Identifier: GPL-2.0-only
+
+menu "Data Access Monitoring"
+
+config DAMON
+	bool "DAMON: Data Access Monitoring Framework"
+	help
+	  This builds a framework that allows kernel subsystems to monitor
+	  access frequency of each memory region. The information can be useful
+	  for performance-centric DRAM level memory management.
+
+	  See https://damonitor.github.io/doc/html/latest-damon/index.html for
+	  more information.
+
+config DAMON_KUNIT_TEST
+	bool "Test for damon" if !KUNIT_ALL_TESTS
+	depends on DAMON && KUNIT=y
+	default KUNIT_ALL_TESTS
+	help
+	  This builds the DAMON Kunit test suite.
+
+	  For more information on KUnit and unit tests in general, please refer
+	  to the KUnit documentation.
+
+	  If unsure, say N.
+
+config DAMON_VADDR
+	bool "Data access monitoring primitives for virtual address spaces"
+	depends on DAMON && MMU
+	select PAGE_IDLE_FLAG
+	help
+	  This builds the default data access monitoring primitives for DAMON
+	  that works for virtual address spaces.
+
+config DAMON_VADDR_KUNIT_TEST
+	bool "Test for DAMON primitives" if !KUNIT_ALL_TESTS
+	depends on DAMON_VADDR && KUNIT=y
+	default KUNIT_ALL_TESTS
+	help
+	  This builds the DAMON virtual addresses primitives Kunit test suite.
+
+	  For more information on KUnit and unit tests in general, please refer
+	  to the KUnit documentation.
+
+	  If unsure, say N.
+
+config DAMON_DBGFS
+	bool "DAMON debugfs interface"
+	depends on DAMON_VADDR && DEBUG_FS
+	help
+	  This builds the debugfs interface for DAMON.  The user space admins
+	  can use the interface for arbitrary data access monitoring.
+
+	  If unsure, say N.
+
+config DAMON_DBGFS_KUNIT_TEST
+	bool "Test for damon debugfs interface" if !KUNIT_ALL_TESTS
+	depends on DAMON_DBGFS && KUNIT=y
+	default KUNIT_ALL_TESTS
+	help
+	  This builds the DAMON debugfs interface Kunit test suite.
+
+	  For more information on KUnit and unit tests in general, please refer
+	  to the KUnit documentation.
+
+	  If unsure, say N.
+
+endmenu

mm/damon/Makefile

···
+# SPDX-License-Identifier: GPL-2.0
+
+obj-$(CONFIG_DAMON)		:= core.o
+obj-$(CONFIG_DAMON_VADDR)	+= vaddr.o
+obj-$(CONFIG_DAMON_DBGFS)	+= dbgfs.o

mm/damon/core-test.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Data Access Monitor Unit Tests
+ *
+ * Copyright 2019 Amazon.com, Inc. or its affiliates.  All rights reserved.
+ *
+ * Author: SeongJae Park <[e-mail]>
+ */
+
+#ifdef CONFIG_DAMON_KUNIT_TEST
+
+#ifndef _DAMON_CORE_TEST_H
+#define _DAMON_CORE_TEST_H
+
+#include <kunit/test.h>
+
+static void damon_test_regions(struct kunit *test)
+{
+	struct damon_region *r;
+	struct damon_target *t;
+
+	r = damon_new_region(1, 2);
+	KUNIT_EXPECT_EQ(test, 1ul, r->ar.start);
+	KUNIT_EXPECT_EQ(test, 2ul, r->ar.end);
+	KUNIT_EXPECT_EQ(test, 0u, r->nr_accesses);
+
+	t = damon_new_target(42);
+	KUNIT_EXPECT_EQ(test, 0u, damon_nr_regions(t));
+
+	damon_add_region(r, t);
+	KUNIT_EXPECT_EQ(test, 1u, damon_nr_regions(t));
+
+	damon_del_region(r, t);
+	KUNIT_EXPECT_EQ(test, 0u, damon_nr_regions(t));
+
+	damon_free_target(t);
+}
+
+static unsigned int nr_damon_targets(struct damon_ctx *ctx)
+{
+	struct damon_target *t;
+	unsigned int nr_targets = 0;
+
+	damon_for_each_target(t, ctx)
+		nr_targets++;
+
+	return nr_targets;
+}
+
+static void damon_test_target(struct kunit *test)
+{
+	struct damon_ctx *c = damon_new_ctx();
+	struct damon_target *t;
+
+	t = damon_new_target(42);
+	KUNIT_EXPECT_EQ(test, 42ul, t->id);
+	KUNIT_EXPECT_EQ(test, 0u, nr_damon_targets(c));
+
+	damon_add_target(c, t);
+	KUNIT_EXPECT_EQ(test, 1u, nr_damon_targets(c));
+
+	damon_destroy_target(t);
+	KUNIT_EXPECT_EQ(test, 0u, nr_damon_targets(c));
+
+	damon_destroy_ctx(c);
+}
+
+/*
+ * Test kdamond_reset_aggregated()
+ *
+ * DAMON checks access to each region and aggregates this information as the
+ * access frequency of each region.  In detail, it increases '->nr_accesses' of
+ * regions that an access has confirmed.  'kdamond_reset_aggregated()' flushes
+ * the aggregated information ('->nr_accesses' of each regions) to the result
+ * buffer.  As a result of the flushing, the '->nr_accesses' of regions are
+ * initialized to zero.
+ */
+static void damon_test_aggregate(struct kunit *test)
+{
+	struct damon_ctx *ctx = damon_new_ctx();
+	unsigned long target_ids[] = {1, 2, 3};
+	unsigned long saddr[][3] = {{10, 20, 30}, {5, 42, 49}, {13, 33, 55} };
+	unsigned long eaddr[][3] = {{15, 27, 40}, {31, 45, 55}, {23, 44, 66} };
+	unsigned long accesses[][3] = {{42, 95, 84}, {10, 20, 30}, {0, 1, 2} };
+	struct damon_target *t;
+	struct damon_region *r;
+	int it, ir;
+
+	damon_set_targets(ctx, target_ids, 3);
+
+	it = 0;
+	damon_for_each_target(t, ctx) {
+		for (ir = 0; ir < 3; ir++) {
+			r = damon_new_region(saddr[it][ir], eaddr[it][ir]);
+			r->nr_accesses = accesses[it][ir];
+			damon_add_region(r, t);
+		}
+		it++;
+	}
+	kdamond_reset_aggregated(ctx);
+	it = 0;
+	damon_for_each_target(t, ctx) {
+		ir = 0;
+		/* '->nr_accesses' should be zeroed */
+		damon_for_each_region(r, t) {
+			KUNIT_EXPECT_EQ(test, 0u, r->nr_accesses);
+			ir++;
+		}
+		/* regions should be preserved */
+		KUNIT_EXPECT_EQ(test, 3, ir);
+		it++;
+	}
+	/* targets also should be preserved */
+	KUNIT_EXPECT_EQ(test, 3, it);
+
+	damon_destroy_ctx(ctx);
+}
+
+static void damon_test_split_at(struct kunit *test)
+{
+	struct damon_ctx *c = damon_new_ctx();
+	struct damon_target *t;
+	struct damon_region *r;
+
+	t = damon_new_target(42);
+	r = damon_new_region(0, 100);
+	damon_add_region(r, t);
+	damon_split_region_at(c, t, r, 25);
+	KUNIT_EXPECT_EQ(test, r->ar.start, 0ul);
+	KUNIT_EXPECT_EQ(test, r->ar.end, 25ul);
+
+	r = damon_next_region(r);
+	KUNIT_EXPECT_EQ(test, r->ar.start, 25ul);
+	KUNIT_EXPECT_EQ(test, r->ar.end, 100ul);
+
+	damon_free_target(t);
+	damon_destroy_ctx(c);
+}
+
+static void damon_test_merge_two(struct kunit *test)
+{
+	struct damon_target *t;
+	struct damon_region *r, *r2, *r3;
+	int i;
+
+	t = damon_new_target(42);
+	r = damon_new_region(0, 100);
+	r->nr_accesses = 10;
+	damon_add_region(r, t);
+	r2 = damon_new_region(100, 300);
+	r2->nr_accesses = 20;
+	damon_add_region(r2, t);
+
+	damon_merge_two_regions(t, r, r2);
+	KUNIT_EXPECT_EQ(test, r->ar.start, 0ul);
+	KUNIT_EXPECT_EQ(test, r->ar.end, 300ul);
+	KUNIT_EXPECT_EQ(test, r->nr_accesses, 16u);
+
+	i = 0;
+	damon_for_each_region(r3, t) {
+		KUNIT_EXPECT_PTR_EQ(test, r, r3);
+		i++;
+	}
+	KUNIT_EXPECT_EQ(test, i, 1);
+
+	damon_free_target(t);
+}
+
+static struct damon_region *__nth_region_of(struct damon_target *t, int idx)
+{
+	struct damon_region *r;
+	unsigned int i = 0;
+
+	damon_for_each_region(r, t) {
+		if (i++ == idx)
+			return r;
+	}
+
+	return NULL;
+}
+
+static void damon_test_merge_regions_of(struct kunit *test)
+{
+	struct damon_target *t;
+	struct damon_region *r;
+	unsigned long sa[] = {0, 100, 114, 122, 130, 156, 170, 184};
+	unsigned long ea[] = {100, 112, 122, 130, 156, 170, 184, 230};
+	unsigned int nrs[] = {0, 0, 10, 10, 20, 30, 1, 2};
+
+	unsigned long saddrs[] = {0, 114, 130, 156, 170};
+	unsigned long eaddrs[] = {112, 130, 156, 170, 230};
+	int i;
+
+	t = damon_new_target(42);
+	for (i = 0; i < ARRAY_SIZE(sa); i++) {
+		r = damon_new_region(sa[i], ea[i]);
+		r->nr_accesses = nrs[i];
+		damon_add_region(r, t);
+	}
+
+	damon_merge_regions_of(t, 9, 9999);
+	/* 0-112, 114-130, 130-156, 156-170 */
+	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 5u);
+	for (i = 0; i < 5; i++) {
+		r = __nth_region_of(t, i);
+		KUNIT_EXPECT_EQ(test, r->ar.start, saddrs[i]);
+		KUNIT_EXPECT_EQ(test, r->ar.end, eaddrs[i]);
+	}
+	damon_free_target(t);
+}
+
+static void damon_test_split_regions_of(struct kunit *test)
+{
+	struct damon_ctx *c = damon_new_ctx();
+	struct damon_target *t;
+	struct damon_region *r;
+
+	t = damon_new_target(42);
+	r = damon_new_region(0, 22);
+	damon_add_region(r, t);
+	damon_split_regions_of(c, t, 2);
+	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 2u);
+	damon_free_target(t);
+
+	t = damon_new_target(42);
+	r = damon_new_region(0, 220);
+	damon_add_region(r, t);
+	damon_split_regions_of(c, t, 4);
+	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 4u);
+	damon_free_target(t);
+	damon_destroy_ctx(c);
+}
+
+static struct kunit_case damon_test_cases[] = {
+	KUNIT_CASE(damon_test_target),
+	KUNIT_CASE(damon_test_regions),
+	KUNIT_CASE(damon_test_aggregate),
+	KUNIT_CASE(damon_test_split_at),
+	KUNIT_CASE(damon_test_merge_two),
+	KUNIT_CASE(damon_test_merge_regions_of),
+	KUNIT_CASE(damon_test_split_regions_of),
+	{},
+};
+
+static struct kunit_suite damon_test_suite = {
+	.name = "damon",
+	.test_cases = damon_test_cases,
+};
+kunit_test_suite(damon_test_suite);
+
+#endif /* _DAMON_CORE_TEST_H */
+
+#endif	/* CONFIG_DAMON_KUNIT_TEST */

mm/damon/core.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Data Access Monitor
+ *
+ * Author: SeongJae Park <[e-mail]>
+ */
+
+#define pr_fmt(fmt) "damon: " fmt
+
+#include <linux/damon.h>
+#include <linux/delay.h>
+#include <linux/kthread.h>
+#include <linux/random.h>
+#include <linux/slab.h>
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/damon.h>
+
+#ifdef CONFIG_DAMON_KUNIT_TEST
+#undef DAMON_MIN_REGION
+#define DAMON_MIN_REGION 1
+#endif
+
+/* Get a random number in [l, r) */
+#define damon_rand(l, r) (l + prandom_u32_max(r - l))
+
+static DEFINE_MUTEX(damon_lock);
+static int nr_running_ctxs;
+
+/*
+ * Construct a damon_region struct
+ *
+ * Returns the pointer to the new struct if success, or NULL otherwise
+ */
+struct damon_region *damon_new_region(unsigned long start, unsigned long end)
+{
+	struct damon_region *region;
+
+	region = kmalloc(sizeof(*region), GFP_KERNEL);
+	if (!region)
+		return NULL;
+
+	region->ar.start = start;
+	region->ar.end = end;
+	region->nr_accesses = 0;
+	INIT_LIST_HEAD(&region->list);
+
+	return region;
+}
+
+/*
+ * Add a region between two other regions
+ */
+inline void damon_insert_region(struct damon_region *r,
+		struct damon_region *prev, struct damon_region *next,
+		struct damon_target *t)
+{
+	__list_add(&r->list, &prev->list, &next->list);
+	t->nr_regions++;
+}
+
+void damon_add_region(struct damon_region *r, struct damon_target *t)
+{
+	list_add_tail(&r->list, &t->regions_list);
+	t->nr_regions++;
+}
+
+static void damon_del_region(struct damon_region *r, struct damon_target *t)
+{
+	list_del(&r->list);
+	t->nr_regions--;
+}
+
+static void damon_free_region(struct damon_region *r)
+{
+	kfree(r);
+}
+
+void damon_destroy_region(struct damon_region *r, struct damon_target *t)
+{
+	damon_del_region(r, t);
+	damon_free_region(r);
+}
+
+/*
+ * Construct a damon_target struct
+ *
+ * Returns the pointer to the new struct if success, or NULL otherwise
+ */
+struct damon_target *damon_new_target(unsigned long id)
+{
+	struct damon_target *t;
+
+	t = kmalloc(sizeof(*t), GFP_KERNEL);
+	if (!t)
+		return NULL;
+
+	t->id = id;
+	t->nr_regions = 0;
+	INIT_LIST_HEAD(&t->regions_list);
+
+	return t;
+}
+
+void damon_add_target(struct damon_ctx *ctx, struct damon_target *t)
+{
+	list_add_tail(&t->list, &ctx->adaptive_targets);
+}
+
+static void damon_del_target(struct damon_target *t)
+{
+	list_del(&t->list);
+}
+
+void damon_free_target(struct damon_target *t)
+{
+	struct damon_region *r, *next;
+
+	damon_for_each_region_safe(r, next, t)
+		damon_free_region(r);
+	kfree(t);
+}
+
+void damon_destroy_target(struct damon_target *t)
+{
+	damon_del_target(t);
+	damon_free_target(t);
+}
+
+unsigned int damon_nr_regions(struct damon_target *t)
+{
+	return t->nr_regions;
+}
+
+struct damon_ctx *damon_new_ctx(void)
+{
+	struct damon_ctx *ctx;
+
+	ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
+	if (!ctx)
+		return NULL;
+
+	ctx->sample_interval = 5 * 1000;
+	ctx->aggr_interval = 100 * 1000;
+	ctx->primitive_update_interval = 60 * 1000 * 1000;
+
+	ktime_get_coarse_ts64(&ctx->last_aggregation);
+	ctx->last_primitive_update = ctx->last_aggregation;
+
+	mutex_init(&ctx->kdamond_lock);
+
+	ctx->min_nr_regions = 10;
+	ctx->max_nr_regions = 1000;
+
+	INIT_LIST_HEAD(&ctx->adaptive_targets);
+
+	return ctx;
+}
+
+static void damon_destroy_targets(struct damon_ctx *ctx)
+{
+	struct damon_target *t, *next_t;
+
+	if (ctx->primitive.cleanup) {
+		ctx->primitive.cleanup(ctx);
+		return;
+	}
+
+	damon_for_each_target_safe(t, next_t, ctx)
+		damon_destroy_target(t);
+}
+
+void damon_destroy_ctx(struct damon_ctx *ctx)
+{
+	damon_destroy_targets(ctx);
+	kfree(ctx);
+}
+
+/**
+ * damon_set_targets() - Set monitoring targets.
+ * @ctx:	monitoring context
+ * @ids:	array of target ids
+ * @nr_ids:	number of entries in @ids
+ *
+ * This function should not be called while the kdamond is running.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int damon_set_targets(struct damon_ctx *ctx,
+		      unsigned long *ids, ssize_t nr_ids)
+{
+	ssize_t i;
+	struct damon_target *t, *next;
+
+	damon_destroy_targets(ctx);
+
+	for (i = 0; i < nr_ids; i++) {
+		t = damon_new_target(ids[i]);
+		if (!t) {
+			pr_err("Failed to alloc damon_target\n");
+			/* The caller should do cleanup of the ids itself */
+			damon_for_each_target_safe(t, next, ctx)
+				damon_destroy_target(t);
+			return -ENOMEM;
+		}
+		damon_add_target(ctx, t);
+	}
+
+	return 0;
+}
+
+/**
+ * damon_set_attrs() - Set attributes for the monitoring.
+ * @ctx:		monitoring context
+ * @sample_int:		time interval between samplings
+ * @aggr_int:		time interval between aggregations
+ * @primitive_upd_int:	time interval between monitoring primitive updates
+ * @min_nr_reg:		minimal number of regions
+ * @max_nr_reg:		maximum number of regions
+ *
+ * This function should not be called while the kdamond is running.
+ * Every time interval is in micro-seconds.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int damon_set_attrs(struct damon_ctx *ctx, unsigned long sample_int,
+		    unsigned long aggr_int, unsigned long primitive_upd_int,
+		    unsigned long min_nr_reg, unsigned long max_nr_reg)
+{
+	if (min_nr_reg < 3) {
+		pr_err("min_nr_regions (%lu) must be at least 3\n",
+				min_nr_reg);
+		return -EINVAL;
+	}
+	if (min_nr_reg > max_nr_reg) {
+		pr_err("invalid nr_regions.  min (%lu) > max (%lu)\n",
+				min_nr_reg, max_nr_reg);
+		return -EINVAL;
+	}
+
+	ctx->sample_interval = sample_int;
+	ctx->aggr_interval = aggr_int;
+	ctx->primitive_update_interval = primitive_upd_int;
+	ctx->min_nr_regions = min_nr_reg;
+	ctx->max_nr_regions = max_nr_reg;
+
+	return 0;
+}
+
+/**
+ * damon_nr_running_ctxs() - Return number of currently running contexts.
+ */
+int damon_nr_running_ctxs(void)
+{
+	int nr_ctxs;
+
+	mutex_lock(&damon_lock);
+	nr_ctxs = nr_running_ctxs;
+	mutex_unlock(&damon_lock);
+
+	return nr_ctxs;
+}
+
+/* Returns the size upper limit for each monitoring region */
+static unsigned long damon_region_sz_limit(struct damon_ctx *ctx)
+{
+	struct damon_target *t;
+	struct damon_region *r;
+	unsigned long sz = 0;
+
+	damon_for_each_target(t, ctx) {
+		damon_for_each_region(r, t)
+			sz += r->ar.end - r->ar.start;
+	}
+
+	if (ctx->min_nr_regions)
+		sz /= ctx->min_nr_regions;
+	if (sz < DAMON_MIN_REGION)
+		sz = DAMON_MIN_REGION;
+
+	return sz;
+}
+
+static bool damon_kdamond_running(struct damon_ctx *ctx)
+{
+	bool running;
+
+	mutex_lock(&ctx->kdamond_lock);
+	running = ctx->kdamond != NULL;
+	mutex_unlock(&ctx->kdamond_lock);
+
+	return running;
+}
+
+static int kdamond_fn(void *data);
+
+/*
+ * __damon_start() - Starts monitoring with given context.
+ * @ctx:	monitoring context
+ *
+ * This function should be called while damon_lock is hold.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+static int __damon_start(struct damon_ctx *ctx)
+{
+	int err = -EBUSY;
+
+	mutex_lock(&ctx->kdamond_lock);
+	if (!ctx->kdamond) {
+		err = 0;
+		ctx->kdamond_stop = false;
+		ctx->kdamond = kthread_run(kdamond_fn, ctx, "kdamond.%d",
+				nr_running_ctxs);
+		if (IS_ERR(ctx->kdamond)) {
+			err = PTR_ERR(ctx->kdamond);
+			ctx->kdamond = 0;
+		}
+	}
+	mutex_unlock(&ctx->kdamond_lock);
+
+	return err;
+}
+
+/**
+ * damon_start() - Starts the monitorings for a given group of contexts.
+ * @ctxs:	an array of the pointers for contexts to start monitoring
+ * @nr_ctxs:	size of @ctxs
+ *
+ * This function starts a group of monitoring threads for a group of monitoring
+ * contexts.  One thread per each context is created and run in parallel.  The
+ * caller should handle synchronization between the threads by itself.  If a
+ * group of threads that created by other 'damon_start()' call is currently
+ * running, this function does nothing but returns -EBUSY.
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int damon_start(struct damon_ctx **ctxs, int nr_ctxs)
+{
+	int i;
+	int err = 0;
+
+	mutex_lock(&damon_lock);
+	if (nr_running_ctxs) {
+		mutex_unlock(&damon_lock);
+		return -EBUSY;
+	}
+
+	for (i = 0; i < nr_ctxs; i++) {
+		err = __damon_start(ctxs[i]);
+		if (err)
+			break;
+		nr_running_ctxs++;
+	}
+	mutex_unlock(&damon_lock);
+
+	return err;
+}
+
+/*
+ * __damon_stop() - Stops monitoring of given context.
+ * @ctx:	monitoring context
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+static int __damon_stop(struct damon_ctx *ctx)
+{
+	mutex_lock(&ctx->kdamond_lock);
+	if (ctx->kdamond) {
+		ctx->kdamond_stop = true;
+		mutex_unlock(&ctx->kdamond_lock);
+		while (damon_kdamond_running(ctx))
+			usleep_range(ctx->sample_interval,
+					ctx->sample_interval * 2);
+		return 0;
+	}
+	mutex_unlock(&ctx->kdamond_lock);
+
+	return -EPERM;
+}
+
+/**
+ * damon_stop() - Stops the monitorings for a given group of contexts.
+ * @ctxs:	an array of the pointers for contexts to stop monitoring
+ * @nr_ctxs:	size of @ctxs
+ *
+ * Return: 0 on success, negative error code otherwise.
+ */
+int damon_stop(struct damon_ctx **ctxs, int nr_ctxs)
+{
+	int i, err = 0;
+
+	for (i = 0; i < nr_ctxs; i++) {
+		/* nr_running_ctxs is decremented in kdamond_fn */
+		err = __damon_stop(ctxs[i]);
+		if (err)
+			return err;
+	}
+
+	return err;
+}
+
+/*
+ * damon_check_reset_time_interval() - Check if a time interval is elapsed.
+ * @baseline:	the time to check whether the interval has elapsed since
+ * @interval:	the time interval (microseconds)
+ *
+ * See whether the given time interval has passed since the given baseline
+ * time.  If so, it also updates the baseline to current time for next check.
+ *
+ * Return:	true if the time interval has passed, or false otherwise.
+ */
+static bool damon_check_reset_time_interval(struct timespec64 *baseline,
+		unsigned long interval)
+{
+	struct timespec64 now;
+
+	ktime_get_coarse_ts64(&now);
+	if ((timespec64_to_ns(&now) - timespec64_to_ns(baseline)) <
+			interval * 1000)
+		return false;
+	*baseline = now;
+	return true;
+}
+
+/*
+ * Check whether it is time to flush the aggregated information
+ */
+static bool kdamond_aggregate_interval_passed(struct damon_ctx *ctx)
+{
+	return damon_check_reset_time_interval(&ctx->last_aggregation,
+			ctx->aggr_interval);
+}
+
+/*
+ * Reset the aggregated monitoring results ('nr_accesses' of each region).
+ */
+static void kdamond_reset_aggregated(struct damon_ctx *c)
+{
+	struct damon_target *t;
+
+	damon_for_each_target(t, c) {
+		struct damon_region *r;
+
+		damon_for_each_region(r, t) {
+			trace_damon_aggregated(t, r, damon_nr_regions(t));
+			r->nr_accesses = 0;
+		}
+	}
+}
+
+#define sz_damon_region(r) (r->ar.end - r->ar.start)
+
+/*
+ * Merge two adjacent regions into one region
+ */
+static void damon_merge_two_regions(struct damon_target *t,
+		struct damon_region *l, struct damon_region *r)
+{
+	unsigned long sz_l = sz_damon_region(l), sz_r = sz_damon_region(r);
+
+	l->nr_accesses = (l->nr_accesses * sz_l + r->nr_accesses * sz_r) /
+			(sz_l + sz_r);
+	l->ar.end = r->ar.end;
+	damon_destroy_region(r, t);
+}
+
+#define diff_of(a, b) (a > b ? a - b : b - a)
+
+/*
+ * Merge adjacent regions having similar access frequencies
+ *
+ * t		target affected by this merge operation
+ * thres	'->nr_accesses' diff threshold for the merge
+ * sz_limit	size upper limit of each region
+ */
+static void damon_merge_regions_of(struct damon_target *t, unsigned int thres,
+				   unsigned long sz_limit)
+{
+	struct damon_region *r, *prev = NULL, *next;
+
+	damon_for_each_region_safe(r, next, t) {
+		if (prev && prev->ar.end == r->ar.start &&
+		    diff_of(prev->nr_accesses, r->nr_accesses) <= thres &&
+		    sz_damon_region(prev) + sz_damon_region(r) <= sz_limit)
+			damon_merge_two_regions(t, prev, r);
+		else
+			prev = r;
+	}
+}
+
+/*
+ * Merge adjacent regions having similar access frequencies
+ *
+ * threshold	'->nr_accesses' diff threshold for the merge
+ * sz_limit	size upper limit of each region
+ *
+ * This function merges monitoring target regions which are adjacent and their
+ * access frequencies are similar.  This is for minimizing the monitoring
+ * overhead under the dynamically changeable access pattern.  If a merge was
+ * unnecessarily made, later 'kdamond_split_regions()' will revert it.
+ */
+static void kdamond_merge_regions(struct damon_ctx *c, unsigned int threshold,
+				  unsigned long sz_limit)
+{
+	struct damon_target *t;
+
+	damon_for_each_target(t, c)
+		damon_merge_regions_of(t, threshold, sz_limit);
+}
+
+/*
+ * Split a region in two
+ *
+ * r		the region to be split
+ * sz_r		size of the first sub-region that will be made
+ */
+static void damon_split_region_at(struct damon_ctx *ctx,
+		struct damon_target *t, struct damon_region *r,
+		unsigned long sz_r)
+{
+	struct damon_region *new;
+
+	new = damon_new_region(r->ar.start + sz_r, r->ar.end);
+	if (!new)
+		return;
+
+	r->ar.end = new->ar.start;
+
+	damon_insert_region(new, r, damon_next_region(r), t);
+}
+
+/* Split every region in the given target into 'nr_subs' regions */
+static void damon_split_regions_of(struct damon_ctx *ctx,
+				     struct damon_target *t, int nr_subs)
+{
+	struct damon_region *r, *next;
+	unsigned long sz_region, sz_sub = 0;
+	int i;
+
+	damon_for_each_region_safe(r, next, t) {
+		sz_region = r->ar.end - r->ar.start;
+
+		for (i = 0; i < nr_subs - 1 &&
+				sz_region > 2 * DAMON_MIN_REGION; i++) {
+			/*
+			 * Randomly select size of left sub-region to be at
+			 * least 10 percent and at most 90% of original region
+			 */
+			sz_sub = ALIGN_DOWN(damon_rand(1, 10) *
+					sz_region / 10, DAMON_MIN_REGION);
+			/* Do not allow blank region */
+			if (sz_sub == 0 || sz_sub >= sz_region)
+				continue;
+
+			damon_split_region_at(ctx, t, r, sz_sub);
+			sz_region = sz_sub;
+		}
+	}
+}
+
+/*
+ * Split every target region into randomly-sized small regions
+ *
+ * This function splits every target region into random-sized small regions if
+ * current total number of the regions is equal or smaller than half of the
+ * user-specified maximum number of regions.  This is for maximizing the
+ * monitoring accuracy under the dynamically changeable access patterns.  If a
+ * split was unnecessarily made, later 'kdamond_merge_regions()' will revert
+ * it.
+ */
+static void kdamond_split_regions(struct damon_ctx *ctx)
+{
+	struct damon_target *t;
+	unsigned int nr_regions = 0;
+	static unsigned int last_nr_regions;
+	int nr_subregions = 2;
+
+	damon_for_each_target(t, ctx)
+		nr_regions += damon_nr_regions(t);
+
+	if (nr_regions > ctx->max_nr_regions / 2)
+		return;
+
+	/* Maybe the middle of the region has different access frequency */
+	if (last_nr_regions == nr_regions &&
+			nr_regions < ctx->max_nr_regions / 3)
+		nr_subregions = 3;
+
+	damon_for_each_target(t, ctx)
+		damon_split_regions_of(ctx, t, nr_subregions);
+
+	last_nr_regions = nr_regions;
+}
+
+/*
+ * Check whether it is time to check and apply the target monitoring regions
+ *
+ * Returns true if it is.
+ */
+static bool kdamond_need_update_primitive(struct damon_ctx *ctx)
+{
+	return damon_check_reset_time_interval(&ctx->last_primitive_update,
+			ctx->primitive_update_interval);
+}
+
+/*
+ * Check whether current monitoring should be stopped
+ *
+ * The monitoring is stopped when either the user requested to stop, or all
+ * monitoring targets are invalid.
+ *
+ * Returns true if need to stop current monitoring.
+ */
+static bool kdamond_need_stop(struct damon_ctx *ctx)
+{
+	struct damon_target *t;
+	bool stop;
+
+	mutex_lock(&ctx->kdamond_lock);
+	stop = ctx->kdamond_stop;
+	mutex_unlock(&ctx->kdamond_lock);
+	if (stop)
+		return true;
+
+	if (!ctx->primitive.target_valid)
+		return false;
+
+	damon_for_each_target(t, ctx) {
+		if (ctx->primitive.target_valid(t))
+			return false;
+	}
+
+	return true;
+}
+
+static void set_kdamond_stop(struct damon_ctx *ctx)
+{
+	mutex_lock(&ctx->kdamond_lock);
+	ctx->kdamond_stop = true;
+	mutex_unlock(&ctx->kdamond_lock);
+}
+
+/*
+ * The monitoring daemon that runs as a kernel thread
+ */
+static int kdamond_fn(void *data)
+{
+	struct damon_ctx *ctx = (struct damon_ctx *)data;
+	struct damon_target *t;
+	struct damon_region *r, *next;
+	unsigned int max_nr_accesses = 0;
+	unsigned long sz_limit = 0;
+
+	mutex_lock(&ctx->kdamond_lock);
+	pr_info("kdamond (%d) starts\n", ctx->kdamond->pid);
+	mutex_unlock(&ctx->kdamond_lock);
+
+	if (ctx->primitive.init)
+		ctx->primitive.init(ctx);
+	if (ctx->callback.before_start && ctx->callback.before_start(ctx))
+		set_kdamond_stop(ctx);
+
+	sz_limit = damon_region_sz_limit(ctx);
+
+	while (!kdamond_need_stop(ctx)) {
+		if (ctx->primitive.prepare_access_checks)
+			ctx->primitive.prepare_access_checks(ctx);
+		if (ctx->callback.after_sampling &&
+				ctx->callback.after_sampling(ctx))
+			set_kdamond_stop(ctx);
+
+		usleep_range(ctx->sample_interval, ctx->sample_interval + 1);
+
+		if (ctx->primitive.check_accesses)
+			max_nr_accesses = ctx->primitive.check_accesses(ctx);
+
+		if (kdamond_aggregate_interval_passed(ctx)) {
+			kdamond_merge_regions(ctx,
+					max_nr_accesses / 10,
+					sz_limit);
+			if (ctx->callback.after_aggregation &&
+					ctx->callback.after_aggregation(ctx))
+				set_kdamond_stop(ctx);
+			kdamond_reset_aggregated(ctx);
+			kdamond_split_regions(ctx);
+			if (ctx->primitive.reset_aggregated)
+				ctx->primitive.reset_aggregated(ctx);
+		}
+
+		if (kdamond_need_update_primitive(ctx)) {
+			if (ctx->primitive.update)
+				ctx->primitive.update(ctx);
+			sz_limit = damon_region_sz_limit(ctx);
+		}
+	}
+	damon_for_each_target(t, ctx) {
+		damon_for_each_region_safe(r, next, t)
+			damon_destroy_region(r, t);
+	}
+
+	if (ctx->callback.before_terminate &&
+			ctx->callback.before_terminate(ctx))
+		set_kdamond_stop(ctx);
+	if (ctx->primitive.cleanup)
+		ctx->primitive.cleanup(ctx);
+
+	pr_debug("kdamond (%d) finishes\n", ctx->kdamond->pid);
+	mutex_lock(&ctx->kdamond_lock);
+	ctx->kdamond = NULL;
+	mutex_unlock(&ctx->kdamond_lock);
+
+	mutex_lock(&damon_lock);
+	nr_running_ctxs--;
+	mutex_unlock(&damon_lock);
+
+	do_exit(0);
+}
+
+#include "core-test.h"

mm/damon/dbgfs-test.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * DAMON Debugfs Interface Unit Tests
+ *
+ * Author: SeongJae Park <[e-mail]>
+ */
+
+#ifdef CONFIG_DAMON_DBGFS_KUNIT_TEST
+
+#ifndef _DAMON_DBGFS_TEST_H
+#define _DAMON_DBGFS_TEST_H
+
+#include <kunit/test.h>
+
+static void damon_dbgfs_test_str_to_target_ids(struct kunit *test)
+{
+	char *question;
+	unsigned long *answers;
+	unsigned long expected[] = {12, 35, 46};
+	ssize_t nr_integers = 0, i;
+
+	question = "123";
+	answers = str_to_target_ids(question, strnlen(question, 128),
+			&nr_integers);
+	KUNIT_EXPECT_EQ(test, (ssize_t)1, nr_integers);
+	KUNIT_EXPECT_EQ(test, 123ul, answers[0]);
+	kfree(answers);
+
+	question = "123abc";
+	answers = str_to_target_ids(question, strnlen(question, 128),
+			&nr_integers);
+	KUNIT_EXPECT_EQ(test, (ssize_t)1, nr_integers);
+	KUNIT_EXPECT_EQ(test, 123ul, answers[0]);
+	kfree(answers);
+
+	question = "a123";
+	answers = str_to_target_ids(question, strnlen(question, 128),
+			&nr_integers);
+	KUNIT_EXPECT_EQ(test, (ssize_t)0, nr_integers);
+	kfree(answers);
+
+	question = "12 35";
+	answers = str_to_target_ids(question, strnlen(question, 128),
+			&nr_integers);
+	KUNIT_EXPECT_EQ(test, (ssize_t)2, nr_integers);
+	for (i = 0; i < nr_integers; i++)
+		KUNIT_EXPECT_EQ(test, expected[i], answers[i]);
+	kfree(answers);
+
+	question = "12 35 46";
+	answers = str_to_target_ids(question, strnlen(question, 128),
+			&nr_integers);
+	KUNIT_EXPECT_EQ(test, (ssize_t)3, nr_integers);
+	for (i = 0; i < nr_integers; i++)
+		KUNIT_EXPECT_EQ(test, expected[i], answers[i]);
+	kfree(answers);
+
+	question = "12 35 abc 46";
+	answers = str_to_target_ids(question, strnlen(question, 128),
+			&nr_integers);
+	KUNIT_EXPECT_EQ(test, (ssize_t)2, nr_integers);
+	for (i = 0; i < 2; i++)
+		KUNIT_EXPECT_EQ(test, expected[i], answers[i]);
+	kfree(answers);
+
+	question = "";
+	answers = str_to_target_ids(question, strnlen(question, 128),
+			&nr_integers);
+	KUNIT_EXPECT_EQ(test, (ssize_t)0, nr_integers);
+	kfree(answers);
+
+	question = "\n";
+	answers = str_to_target_ids(question, strnlen(question, 128),
+			&nr_integers);
+	KUNIT_EXPECT_EQ(test, (ssize_t)0, nr_integers);
+	kfree(answers);
+}
+
+static void damon_dbgfs_test_set_targets(struct kunit *test)
+{
+	struct damon_ctx *ctx = dbgfs_new_ctx();
+	unsigned long ids[] = {1, 2, 3};
+	char buf[64];
+
+	/* Make DAMON consider target id as plain number */
+	ctx->primitive.target_valid = NULL;
+	ctx->primitive.cleanup = NULL;
+
+	damon_set_targets(ctx, ids, 3);
+	sprint_target_ids(ctx, buf, 64);
+	KUNIT_EXPECT_STREQ(test, (char *)buf, "1 2 3\n");
+
+	damon_set_targets(ctx, NULL, 0);
+	sprint_target_ids(ctx, buf, 64);
+	KUNIT_EXPECT_STREQ(test, (char *)buf, "\n");
+
+	damon_set_targets(ctx, (unsigned long []){1, 2}, 2);
+	sprint_target_ids(ctx, buf, 64);
+	KUNIT_EXPECT_STREQ(test, (char *)buf, "1 2\n");
+
+	damon_set_targets(ctx, (unsigned long []){2}, 1);
+	sprint_target_ids(ctx, buf, 64);
+	KUNIT_EXPECT_STREQ(test, (char *)buf, "2\n");
+
+	damon_set_targets(ctx, NULL, 0);
+	sprint_target_ids(ctx, buf, 64);
+	KUNIT_EXPECT_STREQ(test, (char *)buf, "\n");
+
+	dbgfs_destroy_ctx(ctx);
+}
+
+static struct kunit_case damon_test_cases[] = {
+	KUNIT_CASE(damon_dbgfs_test_str_to_target_ids),
+	KUNIT_CASE(damon_dbgfs_test_set_targets),
+	{},
+};
+
+static struct kunit_suite damon_test_suite = {
+	.name = "damon-dbgfs",
+	.test_cases = damon_test_cases,
+};
+kunit_test_suite(damon_test_suite);
+
+#endif /* _DAMON_TEST_H */
+
+#endif	/* CONFIG_DAMON_KUNIT_TEST */

mm/damon/dbgfs.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * DAMON Debugfs Interface
+ *
+ * Author: SeongJae Park <[e-mail]>
+ */
+
+#define pr_fmt(fmt) "damon-dbgfs: " fmt
+
+#include <linux/damon.h>
+#include <linux/debugfs.h>
+#include <linux/file.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/page_idle.h>
+#include <linux/slab.h>
+
+static struct damon_ctx **dbgfs_ctxs;
+static int dbgfs_nr_ctxs;
+static struct dentry **dbgfs_dirs;
+static DEFINE_MUTEX(damon_dbgfs_lock);
+
+/*
+ * Returns non-empty string on success, negative error code otherwise.
+ */
+static char *user_input_str(const char __user *buf, size_t count, loff_t *ppos)
+{
+	char *kbuf;
+	ssize_t ret;
+
+	/* We do not accept continuous write */
+	if (*ppos)
+		return ERR_PTR(-EINVAL);
+
+	kbuf = kmalloc(count + 1, GFP_KERNEL);
+	if (!kbuf)
+		return ERR_PTR(-ENOMEM);
+
+	ret = simple_write_to_buffer(kbuf, count + 1, ppos, buf, count);
+	if (ret != count) {
+		kfree(kbuf);
+		return ERR_PTR(-EIO);
+	}
+	kbuf[ret] = '\0';
+
+	return kbuf;
+}
+
+static ssize_t dbgfs_attrs_read(struct file *file,
+		char __user *buf, size_t count, loff_t *ppos)
+{
+	struct damon_ctx *ctx = file->private_data;
+	char kbuf[128];
+	int ret;
+
+	mutex_lock(&ctx->kdamond_lock);
+	ret = scnprintf(kbuf, ARRAY_SIZE(kbuf), "%lu %lu %lu %lu %lu\n",
+			ctx->sample_interval, ctx->aggr_interval,
+			ctx->primitive_update_interval, ctx->min_nr_regions,
+			ctx->max_nr_regions);
+	mutex_unlock(&ctx->kdamond_lock);
+
+	return simple_read_from_buffer(buf, count, ppos, kbuf, ret);
+}
+
+static ssize_t dbgfs_attrs_write(struct file *file,
+		const char __user *buf, size_t count, loff_t *ppos)
+{
+	struct damon_ctx *ctx = file->private_data;
+	unsigned long s, a, r, minr, maxr;
+	char *kbuf;
+	ssize_t ret = count;
+	int err;
+
+	kbuf = user_input_str(buf, count, ppos);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
+
+	if (sscanf(kbuf, "%lu %lu %lu %lu %lu",
+				&s, &a, &r, &minr, &maxr) != 5) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	mutex_lock(&ctx->kdamond_lock);
+	if (ctx->kdamond) {
+		ret = -EBUSY;
+		goto unlock_out;
+	}
+
+	err = damon_set_attrs(ctx, s, a, r, minr, maxr);
+	if (err)
+		ret = err;
+unlock_out:
+	mutex_unlock(&ctx->kdamond_lock);
+out:
+	kfree(kbuf);
+	return ret;
+}
+
+static inline bool targetid_is_pid(const struct damon_ctx *ctx)
+{
+	return ctx->primitive.target_valid == damon_va_target_valid;
+}
+
+static ssize_t sprint_target_ids(struct damon_ctx *ctx, char *buf, ssize_t len)
+{
+	struct damon_target *t;
+	unsigned long id;
+	int written = 0;
+	int rc;
+
+	damon_for_each_target(t, ctx) {
+		id = t->id;
+		if (targetid_is_pid(ctx))
+			/* Show pid numbers to debugfs users */
+			id = (unsigned long)pid_vnr((struct pid *)id);
+
+		rc = scnprintf(&buf[written], len - written, "%lu ", id);
+		if (!rc)
+			return -ENOMEM;
+		written += rc;
+	}
+	if (written)
+		written -= 1;
+	written += scnprintf(&buf[written], len - written, "\n");
+	return written;
+}
+
+static ssize_t dbgfs_target_ids_read(struct file *file,
+		char __user *buf, size_t count, loff_t *ppos)
+{
+	struct damon_ctx *ctx = file->private_data;
+	ssize_t len;
+	char ids_buf[320];
+
+	mutex_lock(&ctx->kdamond_lock);
+	len = sprint_target_ids(ctx, ids_buf, 320);
+	mutex_unlock(&ctx->kdamond_lock);
+	if (len < 0)
+		return len;
+
+	return simple_read_from_buffer(buf, count, ppos, ids_buf, len);
+}
+
+/*
+ * Converts a string into an array of unsigned long integers
+ *
+ * Returns an array of unsigned long integers if the conversion success, or
+ * NULL otherwise.
+ */
+static unsigned long *str_to_target_ids(const char *str, ssize_t len,
+					ssize_t *nr_ids)
+{
+	unsigned long *ids;
+	const int max_nr_ids = 32;
+	unsigned long id;
+	int pos = 0, parsed, ret;
+
+	*nr_ids = 0;
+	ids = kmalloc_array(max_nr_ids, sizeof(id), GFP_KERNEL);
+	if (!ids)
+		return NULL;
+	while (*nr_ids < max_nr_ids && pos < len) {
+		ret = sscanf(&str[pos], "%lu%n", &id, &parsed);
+		pos += parsed;
+		if (ret != 1)
+			break;
+		ids[*nr_ids] = id;
+		*nr_ids += 1;
+	}
+
+	return ids;
+}
+
+static void dbgfs_put_pids(unsigned long *ids, int nr_ids)
+{
+	int i;
+
+	for (i = 0; i < nr_ids; i++)
+		put_pid((struct pid *)ids[i]);
+}
+
+static ssize_t dbgfs_target_ids_write(struct file *file,
+		const char __user *buf, size_t count, loff_t *ppos)
+{
+	struct damon_ctx *ctx = file->private_data;
+	char *kbuf, *nrs;
+	unsigned long *targets;
+	ssize_t nr_targets;
+	ssize_t ret = count;
+	int i;
+	int err;
+
+	kbuf = user_input_str(buf, count, ppos);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
+
+	nrs = kbuf;
+
+	targets = str_to_target_ids(nrs, ret, &nr_targets);
+	if (!targets) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	if (targetid_is_pid(ctx)) {
+		for (i = 0; i < nr_targets; i++) {
+			targets[i] = (unsigned long)find_get_pid(
+					(int)targets[i]);
+			if (!targets[i]) {
+				dbgfs_put_pids(targets, i);
+				ret = -EINVAL;
+				goto free_targets_out;
+			}
+		}
+	}
+
+	mutex_lock(&ctx->kdamond_lock);
+	if (ctx->kdamond) {
+		if (targetid_is_pid(ctx))
+			dbgfs_put_pids(targets, nr_targets);
+		ret = -EBUSY;
+		goto unlock_out;
+	}
+
+	err = damon_set_targets(ctx, targets, nr_targets);
+	if (err) {
+		if (targetid_is_pid(ctx))
+			dbgfs_put_pids(targets, nr_targets);
+		ret = err;
+	}
+
+unlock_out:
+	mutex_unlock(&ctx->kdamond_lock);
+free_targets_out:
+	kfree(targets);
+out:
+	kfree(kbuf);
+	return ret;
+}
+
+static ssize_t dbgfs_kdamond_pid_read(struct file *file,
+		char __user *buf, size_t count, loff_t *ppos)
+{
+	struct damon_ctx *ctx = file->private_data;
+	char *kbuf;
+	ssize_t len;
+
+	kbuf = kmalloc(count, GFP_KERNEL);
+	if (!kbuf)
+		return -ENOMEM;
+
+	mutex_lock(&ctx->kdamond_lock);
+	if (ctx->kdamond)
+		len = scnprintf(kbuf, count, "%d\n", ctx->kdamond->pid);
+	else
+		len = scnprintf(kbuf, count, "none\n");
+	mutex_unlock(&ctx->kdamond_lock);
+	if (!len)
+		goto out;
+	len = simple_read_from_buffer(buf, count, ppos, kbuf, len);
+
+out:
+	kfree(kbuf);
+	return len;
+}
+
+static int damon_dbgfs_open(struct inode *inode, struct file *file)
+{
+	file->private_data = inode->i_private;
+
+	return nonseekable_open(inode, file);
+}
+
+static const struct file_operations attrs_fops = {
+	.open = damon_dbgfs_open,
+	.read = dbgfs_attrs_read,
+	.write = dbgfs_attrs_write,
+};
+
+static const struct file_operations target_ids_fops = {
+	.open = damon_dbgfs_open,
+	.read = dbgfs_target_ids_read,
+	.write = dbgfs_target_ids_write,
+};
+
+static const struct file_operations kdamond_pid_fops = {
+	.open = damon_dbgfs_open,
+	.read = dbgfs_kdamond_pid_read,
+};
+
+static void dbgfs_fill_ctx_dir(struct dentry *dir, struct damon_ctx *ctx)
+{
+	const char * const file_names[] = {"attrs", "target_ids",
+		"kdamond_pid"};
+	const struct file_operations *fops[] = {&attrs_fops, &target_ids_fops,
+		&kdamond_pid_fops};
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(file_names); i++)
+		debugfs_create_file(file_names[i], 0600, dir, ctx, fops[i]);
+}
+
+static int dbgfs_before_terminate(struct damon_ctx *ctx)
+{
+	struct damon_target *t, *next;
+
+	if (!targetid_is_pid(ctx))
+		return 0;
+
+	damon_for_each_target_safe(t, next, ctx) {
+		put_pid((struct pid *)t->id);
+		damon_destroy_target(t);
+	}
+	return 0;
+}
+
+static struct damon_ctx *dbgfs_new_ctx(void)
+{
+	struct damon_ctx *ctx;
+
+	ctx = damon_new_ctx();
+	if (!ctx)
+		return NULL;
+
+	damon_va_set_primitives(ctx);
+	ctx->callback.before_terminate = dbgfs_before_terminate;
+	return ctx;
+}
+
+static void dbgfs_destroy_ctx(struct damon_ctx *ctx)
+{
+	damon_destroy_ctx(ctx);
+}
+
+/*
+ * Make a context of @name and create a debugfs directory for it.
+ *
+ * This function should be called while holding damon_dbgfs_lock.
+ *
+ * Returns 0 on success, negative error code otherwise.
+ */
+static int dbgfs_mk_context(char *name)
+{
+	struct dentry *root, **new_dirs, *new_dir;
+	struct damon_ctx **new_ctxs, *new_ctx;
+
+	if (damon_nr_running_ctxs())
+		return -EBUSY;
+
+	new_ctxs = krealloc(dbgfs_ctxs, sizeof(*dbgfs_ctxs) *
+			(dbgfs_nr_ctxs + 1), GFP_KERNEL);
+	if (!new_ctxs)
+		return -ENOMEM;
+	dbgfs_ctxs = new_ctxs;
+
+	new_dirs = krealloc(dbgfs_dirs, sizeof(*dbgfs_dirs) *
+			(dbgfs_nr_ctxs + 1), GFP_KERNEL);
+	if (!new_dirs)
+		return -ENOMEM;
+	dbgfs_dirs = new_dirs;
+
+	root = dbgfs_dirs[0];
+	if (!root)
+		return -ENOENT;
+
+	new_dir = debugfs_create_dir(name, root);
+	dbgfs_dirs[dbgfs_nr_ctxs] = new_dir;
+
+	new_ctx = dbgfs_new_ctx();
+	if (!new_ctx) {
+		debugfs_remove(new_dir);
+		dbgfs_dirs[dbgfs_nr_ctxs] = NULL;
+		return -ENOMEM;
+	}
+
+	dbgfs_ctxs[dbgfs_nr_ctxs] = new_ctx;
+	dbgfs_fill_ctx_dir(dbgfs_dirs[dbgfs_nr_ctxs],
+			dbgfs_ctxs[dbgfs_nr_ctxs]);
+	dbgfs_nr_ctxs++;
+
+	return 0;
+}
+
+static ssize_t dbgfs_mk_context_write(struct file *file,
+		const char __user *buf, size_t count, loff_t *ppos)
+{
+	char *kbuf;
+	char *ctx_name;
+	ssize_t ret = count;
+	int err;
+
+	kbuf = user_input_str(buf, count, ppos);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
+	ctx_name = kmalloc(count + 1, GFP_KERNEL);
+	if (!ctx_name) {
+		kfree(kbuf);
+		return -ENOMEM;
+	}
+
+	/* Trim white space */
+	if (sscanf(kbuf, "%s", ctx_name) != 1) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	mutex_lock(&damon_dbgfs_lock);
+	err = dbgfs_mk_context(ctx_name);
+	if (err)
+		ret = err;
+	mutex_unlock(&damon_dbgfs_lock);
+
+out:
+	kfree(kbuf);
+	kfree(ctx_name);
+	return ret;
+}
+
+/*
+ * Remove a context of @name and its debugfs directory.
+ *
+ * This function should be called while holding damon_dbgfs_lock.
+ *
+ * Return 0 on success, negative error code otherwise.
+ */
+static int dbgfs_rm_context(char *name)
+{
+	struct dentry *root, *dir, **new_dirs;
+	struct damon_ctx **new_ctxs;
+	int i, j;
+
+	if (damon_nr_running_ctxs())
+		return -EBUSY;
+
+	root = dbgfs_dirs[0];
+	if (!root)
+		return -ENOENT;
+
+	dir = debugfs_lookup(name, root);
+	if (!dir)
+		return -ENOENT;
+
+	new_dirs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_dirs),
+			GFP_KERNEL);
+	if (!new_dirs)
+		return -ENOMEM;
+
+	new_ctxs = kmalloc_array(dbgfs_nr_ctxs - 1, sizeof(*dbgfs_ctxs),
+			GFP_KERNEL);
+	if (!new_ctxs) {
+		kfree(new_dirs);
+		return -ENOMEM;
+	}
+
+	for (i = 0, j = 0; i < dbgfs_nr_ctxs; i++) {
+		if (dbgfs_dirs[i] == dir) {
+			debugfs_remove(dbgfs_dirs[i]);
+			dbgfs_destroy_ctx(dbgfs_ctxs[i]);
+			continue;
+		}
+		new_dirs[j] = dbgfs_dirs[i];
+		new_ctxs[j++] = dbgfs_ctxs[i];
+	}
+
+	kfree(dbgfs_dirs);
+	kfree(dbgfs_ctxs);
+
+	dbgfs_dirs = new_dirs;
+	dbgfs_ctxs = new_ctxs;
+	dbgfs_nr_ctxs--;
+
+	return 0;
+}
+
+static ssize_t dbgfs_rm_context_write(struct file *file,
+		const char __user *buf, size_t count, loff_t *ppos)
+{
+	char *kbuf;
+	ssize_t ret = count;
+	int err;
+	char *ctx_name;
+
+	kbuf = user_input_str(buf, count, ppos);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
+	ctx_name = kmalloc(count + 1, GFP_KERNEL);
+	if (!ctx_name) {
+		kfree(kbuf);
+		return -ENOMEM;
+	}
+
+	/* Trim white space */
+	if (sscanf(kbuf, "%s", ctx_name) != 1) {
+		ret = -EINVAL;
+		goto out;
+	}
+
+	mutex_lock(&damon_dbgfs_lock);
+	err = dbgfs_rm_context(ctx_name);
+	if (err)
+		ret = err;
+	mutex_unlock(&damon_dbgfs_lock);
+
+out:
+	kfree(kbuf);
+	kfree(ctx_name);
+	return ret;
+}
+
+static ssize_t dbgfs_monitor_on_read(struct file *file,
+		char __user *buf, size_t count, loff_t *ppos)
+{
+	char monitor_on_buf[5];
+	bool monitor_on = damon_nr_running_ctxs() != 0;
+	int len;
+
+	len = scnprintf(monitor_on_buf, 5, monitor_on ? "on\n" : "off\n");
+
+	return simple_read_from_buffer(buf, count, ppos, monitor_on_buf, len);
+}
+
+static ssize_t dbgfs_monitor_on_write(struct file *file,
+		const char __user *buf, size_t count, loff_t *ppos)
+{
+	ssize_t ret = count;
+	char *kbuf;
+	int err;
+
+	kbuf = user_input_str(buf, count, ppos);
+	if (IS_ERR(kbuf))
+		return PTR_ERR(kbuf);
+
+	/* Remove white space */
+	if (sscanf(kbuf, "%s", kbuf) != 1) {
+		kfree(kbuf);
+		return -EINVAL;
+	}
+
+	if (!strncmp(kbuf, "on", count))
+		err = damon_start(dbgfs_ctxs, dbgfs_nr_ctxs);
+	else if (!strncmp(kbuf, "off", count))
+		err = damon_stop(dbgfs_ctxs, dbgfs_nr_ctxs);
+	else
+		err = -EINVAL;
+
+	if (err)
+		ret = err;
+	kfree(kbuf);
+	return ret;
+}
+
+static const struct file_operations mk_contexts_fops = {
+	.write = dbgfs_mk_context_write,
+};
+
+static const struct file_operations rm_contexts_fops = {
+	.write = dbgfs_rm_context_write,
+};
+
+static const struct file_operations monitor_on_fops = {
+	.read = dbgfs_monitor_on_read,
+	.write = dbgfs_monitor_on_write,
+};
+
+static int __init __damon_dbgfs_init(void)
+{
+	struct dentry *dbgfs_root;
+	const char * const file_names[] = {"mk_contexts", "rm_contexts",
+		"monitor_on"};
+	const struct file_operations *fops[] = {&mk_contexts_fops,
+		&rm_contexts_fops, &monitor_on_fops};
+	int i;
+
+	dbgfs_root = debugfs_create_dir("damon", NULL);
+
+	for (i = 0; i < ARRAY_SIZE(file_names); i++)
+		debugfs_create_file(file_names[i], 0600, dbgfs_root, NULL,
+				fops[i]);
+	dbgfs_fill_ctx_dir(dbgfs_root, dbgfs_ctxs[0]);
+
+	dbgfs_dirs = kmalloc_array(1, sizeof(dbgfs_root), GFP_KERNEL);
+	if (!dbgfs_dirs) {
+		debugfs_remove(dbgfs_root);
+		return -ENOMEM;
+	}
+	dbgfs_dirs[0] = dbgfs_root;
+
+	return 0;
+}
+
+/*
+ * Functions for the initialization
+ */
+
+static int __init damon_dbgfs_init(void)
+{
+	int rc;
+
+	dbgfs_ctxs = kmalloc(sizeof(*dbgfs_ctxs), GFP_KERNEL);
+	if (!dbgfs_ctxs)
+		return -ENOMEM;
+	dbgfs_ctxs[0] = dbgfs_new_ctx();
+	if (!dbgfs_ctxs[0]) {
+		kfree(dbgfs_ctxs);
+		return -ENOMEM;
+	}
+	dbgfs_nr_ctxs = 1;
+
+	rc = __damon_dbgfs_init();
+	if (rc) {
+		kfree(dbgfs_ctxs[0]);
+		kfree(dbgfs_ctxs);
+		pr_err("%s: dbgfs init failed\n", __func__);
+	}
+
+	return rc;
+}
+
+module_init(damon_dbgfs_init);
+
+#include "dbgfs-test.h"

mm/damon/vaddr-test.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Data Access Monitor Unit Tests
+ *
+ * Copyright 2019 Amazon.com, Inc. or its affiliates.  All rights reserved.
+ *
+ * Author: SeongJae Park <[e-mail]>
+ */
+
+#ifdef CONFIG_DAMON_VADDR_KUNIT_TEST
+
+#ifndef _DAMON_VADDR_TEST_H
+#define _DAMON_VADDR_TEST_H
+
+#include <kunit/test.h>
+
+static void __link_vmas(struct vm_area_struct *vmas, ssize_t nr_vmas)
+{
+	int i, j;
+	unsigned long largest_gap, gap;
+
+	if (!nr_vmas)
+		return;
+
+	for (i = 0; i < nr_vmas - 1; i++) {
+		vmas[i].vm_next = &vmas[i + 1];
+
+		vmas[i].vm_rb.rb_left = NULL;
+		vmas[i].vm_rb.rb_right = &vmas[i + 1].vm_rb;
+
+		largest_gap = 0;
+		for (j = i; j < nr_vmas; j++) {
+			if (j == 0)
+				continue;
+			gap = vmas[j].vm_start - vmas[j - 1].vm_end;
+			if (gap > largest_gap)
+				largest_gap = gap;
+		}
+		vmas[i].rb_subtree_gap = largest_gap;
+	}
+	vmas[i].vm_next = NULL;
+	vmas[i].vm_rb.rb_right = NULL;
+	vmas[i].rb_subtree_gap = 0;
+}
+
+/*
+ * Test __damon_va_three_regions() function
+ *
+ * In case of virtual memory address spaces monitoring, DAMON converts the
+ * complex and dynamic memory mappings of each target task to three
+ * discontiguous regions which cover every mapped areas.  However, the three
+ * regions should not include the two biggest unmapped areas in the original
+ * mapping, because the two biggest areas are normally the areas between 1)
+ * heap and the mmap()-ed regions, and 2) the mmap()-ed regions and stack.
+ * Because these two unmapped areas are very huge but obviously never accessed,
+ * covering the region is just a waste.
+ *
+ * '__damon_va_three_regions() receives an address space of a process.  It
+ * first identifies the start of mappings, end of mappings, and the two biggest
+ * unmapped areas.  After that, based on the information, it constructs the
+ * three regions and returns.  For more detail, refer to the comment of
+ * 'damon_init_regions_of()' function definition in 'mm/damon.c' file.
+ *
+ * For example, suppose virtual address ranges of 10-20, 20-25, 200-210,
+ * 210-220, 300-305, and 307-330 (Other comments represent this mappings in
+ * more short form: 10-20-25, 200-210-220, 300-305, 307-330) of a process are
+ * mapped.  To cover every mappings, the three regions should start with 10,
+ * and end with 305.  The process also has three unmapped areas, 25-200,
+ * 220-300, and 305-307.  Among those, 25-200 and 220-300 are the biggest two
+ * unmapped areas, and thus it should be converted to three regions of 10-25,
+ * 200-220, and 300-330.
+ */
+static void damon_test_three_regions_in_vmas(struct kunit *test)
+{
+	struct damon_addr_range regions[3] = {0,};
+	/* 10-20-25, 200-210-220, 300-305, 307-330 */
+	struct vm_area_struct vmas[] = {
+		(struct vm_area_struct) {.vm_start = 10, .vm_end = 20},
+		(struct vm_area_struct) {.vm_start = 20, .vm_end = 25},
+		(struct vm_area_struct) {.vm_start = 200, .vm_end = 210},
+		(struct vm_area_struct) {.vm_start = 210, .vm_end = 220},
+		(struct vm_area_struct) {.vm_start = 300, .vm_end = 305},
+		(struct vm_area_struct) {.vm_start = 307, .vm_end = 330},
+	};
+
+	__link_vmas(vmas, 6);
+
+	__damon_va_three_regions(&vmas[0], regions);
+
+	KUNIT_EXPECT_EQ(test, 10ul, regions[0].start);
+	KUNIT_EXPECT_EQ(test, 25ul, regions[0].end);
+	KUNIT_EXPECT_EQ(test, 200ul, regions[1].start);
+	KUNIT_EXPECT_EQ(test, 220ul, regions[1].end);
+	KUNIT_EXPECT_EQ(test, 300ul, regions[2].start);
+	KUNIT_EXPECT_EQ(test, 330ul, regions[2].end);
+}
+
+static struct damon_region *__nth_region_of(struct damon_target *t, int idx)
+{
+	struct damon_region *r;
+	unsigned int i = 0;
+
+	damon_for_each_region(r, t) {
+		if (i++ == idx)
+			return r;
+	}
+
+	return NULL;
+}
+
+/*
+ * Test 'damon_va_apply_three_regions()'
+ *
+ * test			kunit object
+ * regions		an array containing start/end addresses of current
+ *			monitoring target regions
+ * nr_regions		the number of the addresses in 'regions'
+ * three_regions	The three regions that need to be applied now
+ * expected		start/end addresses of monitoring target regions that
+ *			'three_regions' are applied
+ * nr_expected		the number of addresses in 'expected'
+ *
+ * The memory mapping of the target processes changes dynamically.  To follow
+ * the change, DAMON periodically reads the mappings, simplifies it to the
+ * three regions, and updates the monitoring target regions to fit in the three
+ * regions.  The update of current target regions is the role of
+ * 'damon_va_apply_three_regions()'.
+ *
+ * This test passes the given target regions and the new three regions that
+ * need to be applied to the function and check whether it updates the regions
+ * as expected.
+ */
+static void damon_do_test_apply_three_regions(struct kunit *test,
+				unsigned long *regions, int nr_regions,
+				struct damon_addr_range *three_regions,
+				unsigned long *expected, int nr_expected)
+{
+	struct damon_ctx *ctx = damon_new_ctx();
+	struct damon_target *t;
+	struct damon_region *r;
+	int i;
+
+	t = damon_new_target(42);
+	for (i = 0; i < nr_regions / 2; i++) {
+		r = damon_new_region(regions[i * 2], regions[i * 2 + 1]);
+		damon_add_region(r, t);
+	}
+	damon_add_target(ctx, t);
+
+	damon_va_apply_three_regions(t, three_regions);
+
+	for (i = 0; i < nr_expected / 2; i++) {
+		r = __nth_region_of(t, i);
+		KUNIT_EXPECT_EQ(test, r->ar.start, expected[i * 2]);
+		KUNIT_EXPECT_EQ(test, r->ar.end, expected[i * 2 + 1]);
+	}
+
+	damon_destroy_ctx(ctx);
+}
+
+/*
+ * This function test most common case where the three big regions are only
+ * slightly changed.  Target regions should adjust their boundary (10-20-30,
+ * 50-55, 70-80, 90-100) to fit with the new big regions or remove target
+ * regions (57-79) that now out of the three regions.
+ */
+static void damon_test_apply_three_regions1(struct kunit *test)
+{
+	/* 10-20-30, 50-55-57-59, 70-80-90-100 */
+	unsigned long regions[] = {10, 20, 20, 30, 50, 55, 55, 57, 57, 59,
+				70, 80, 80, 90, 90, 100};
+	/* 5-27, 45-55, 73-104 */
+	struct damon_addr_range new_three_regions[3] = {
+		(struct damon_addr_range){.start = 5, .end = 27},
+		(struct damon_addr_range){.start = 45, .end = 55},
+		(struct damon_addr_range){.start = 73, .end = 104} };
+	/* 5-20-27, 45-55, 73-80-90-104 */
+	unsigned long expected[] = {5, 20, 20, 27, 45, 55,
+				73, 80, 80, 90, 90, 104};
+
+	damon_do_test_apply_three_regions(test, regions, ARRAY_SIZE(regions),
+			new_three_regions, expected, ARRAY_SIZE(expected));
+}
+
+/*
+ * Test slightly bigger change.  Similar to above, but the second big region
+ * now require two target regions (50-55, 57-59) to be removed.
+ */
+static void damon_test_apply_three_regions2(struct kunit *test)
+{
+	/* 10-20-30, 50-55-57-59, 70-80-90-100 */
+	unsigned long regions[] = {10, 20, 20, 30, 50, 55, 55, 57, 57, 59,
+				70, 80, 80, 90, 90, 100};
+	/* 5-27, 56-57, 65-104 */
+	struct damon_addr_range new_three_regions[3] = {
+		(struct damon_addr_range){.start = 5, .end = 27},
+		(struct damon_addr_range){.start = 56, .end = 57},
+		(struct damon_addr_range){.start = 65, .end = 104} };
+	/* 5-20-27, 56-57, 65-80-90-104 */
+	unsigned long expected[] = {5, 20, 20, 27, 56, 57,
+				65, 80, 80, 90, 90, 104};
+
+	damon_do_test_apply_three_regions(test, regions, ARRAY_SIZE(regions),
+			new_three_regions, expected, ARRAY_SIZE(expected));
+}
+
+/*
+ * Test a big change.  The second big region has totally freed and mapped to
+ * different area (50-59 -> 61-63).  The target regions which were in the old
+ * second big region (50-55-57-59) should be removed and new target region
+ * covering the second big region (61-63) should be created.
+ */
+static void damon_test_apply_three_regions3(struct kunit *test)
+{
+	/* 10-20-30, 50-55-57-59, 70-80-90-100 */
+	unsigned long regions[] = {10, 20, 20, 30, 50, 55, 55, 57, 57, 59,
+				70, 80, 80, 90, 90, 100};
+	/* 5-27, 61-63, 65-104 */
+	struct damon_addr_range new_three_regions[3] = {
+		(struct damon_addr_range){.start = 5, .end = 27},
+		(struct damon_addr_range){.start = 61, .end = 63},
+		(struct damon_addr_range){.start = 65, .end = 104} };
+	/* 5-20-27, 61-63, 65-80-90-104 */
+	unsigned long expected[] = {5, 20, 20, 27, 61, 63,
+				65, 80, 80, 90, 90, 104};
+
+	damon_do_test_apply_three_regions(test, regions, ARRAY_SIZE(regions),
+			new_three_regions, expected, ARRAY_SIZE(expected));
+}
+
+/*
+ * Test another big change.  Both of the second and third big regions (50-59
+ * and 70-100) has totally freed and mapped to different area (30-32 and
+ * 65-68).  The target regions which were in the old second and third big
+ * regions should now be removed and new target regions covering the new second
+ * and third big regions should be crated.
+ */
+static void damon_test_apply_three_regions4(struct kunit *test)
+{
+	/* 10-20-30, 50-55-57-59, 70-80-90-100 */
+	unsigned long regions[] = {10, 20, 20, 30, 50, 55, 55, 57, 57, 59,
+				70, 80, 80, 90, 90, 100};
+	/* 5-7, 30-32, 65-68 */
+	struct damon_addr_range new_three_regions[3] = {
+		(struct damon_addr_range){.start = 5, .end = 7},
+		(struct damon_addr_range){.start = 30, .end = 32},
+		(struct damon_addr_range){.start = 65, .end = 68} };
+	/* expect 5-7, 30-32, 65-68 */
+	unsigned long expected[] = {5, 7, 30, 32, 65, 68};
+
+	damon_do_test_apply_three_regions(test, regions, ARRAY_SIZE(regions),
+			new_three_regions, expected, ARRAY_SIZE(expected));
+}
+
+static void damon_test_split_evenly(struct kunit *test)
+{
+	struct damon_ctx *c = damon_new_ctx();
+	struct damon_target *t;
+	struct damon_region *r;
+	unsigned long i;
+
+	KUNIT_EXPECT_EQ(test, damon_va_evenly_split_region(NULL, NULL, 5),
+			-EINVAL);
+
+	t = damon_new_target(42);
+	r = damon_new_region(0, 100);
+	KUNIT_EXPECT_EQ(test, damon_va_evenly_split_region(t, r, 0), -EINVAL);
+
+	damon_add_region(r, t);
+	KUNIT_EXPECT_EQ(test, damon_va_evenly_split_region(t, r, 10), 0);
+	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 10u);
+
+	i = 0;
+	damon_for_each_region(r, t) {
+		KUNIT_EXPECT_EQ(test, r->ar.start, i++ * 10);
+		KUNIT_EXPECT_EQ(test, r->ar.end, i * 10);
+	}
+	damon_free_target(t);
+
+	t = damon_new_target(42);
+	r = damon_new_region(5, 59);
+	damon_add_region(r, t);
+	KUNIT_EXPECT_EQ(test, damon_va_evenly_split_region(t, r, 5), 0);
+	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 5u);
+
+	i = 0;
+	damon_for_each_region(r, t) {
+		if (i == 4)
+			break;
+		KUNIT_EXPECT_EQ(test, r->ar.start, 5 + 10 * i++);
+		KUNIT_EXPECT_EQ(test, r->ar.end, 5 + 10 * i);
+	}
+	KUNIT_EXPECT_EQ(test, r->ar.start, 5 + 10 * i);
+	KUNIT_EXPECT_EQ(test, r->ar.end, 59ul);
+	damon_free_target(t);
+
+	t = damon_new_target(42);
+	r = damon_new_region(5, 6);
+	damon_add_region(r, t);
+	KUNIT_EXPECT_EQ(test, damon_va_evenly_split_region(t, r, 2), -EINVAL);
+	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1u);
+
+	damon_for_each_region(r, t) {
+		KUNIT_EXPECT_EQ(test, r->ar.start, 5ul);
+		KUNIT_EXPECT_EQ(test, r->ar.end, 6ul);
+	}
+	damon_free_target(t);
+	damon_destroy_ctx(c);
+}
+
+static struct kunit_case damon_test_cases[] = {
+	KUNIT_CASE(damon_test_three_regions_in_vmas),
+	KUNIT_CASE(damon_test_apply_three_regions1),
+	KUNIT_CASE(damon_test_apply_three_regions2),
+	KUNIT_CASE(damon_test_apply_three_regions3),
+	KUNIT_CASE(damon_test_apply_three_regions4),
+	KUNIT_CASE(damon_test_split_evenly),
+	{},
+};
+
+static struct kunit_suite damon_test_suite = {
+	.name = "damon-primitives",
+	.test_cases = damon_test_cases,
+};
+kunit_test_suite(damon_test_suite);
+
+#endif /* _DAMON_VADDR_TEST_H */
+
+#endif	/* CONFIG_DAMON_VADDR_KUNIT_TEST */

mm/damon/vaddr.c

···
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * DAMON Primitives for Virtual Address Spaces
+ *
+ * Author: SeongJae Park <[e-mail]>
+ */
+
+#define pr_fmt(fmt) "damon-va: " fmt
+
+#include <linux/damon.h>
+#include <linux/hugetlb.h>
+#include <linux/mm.h>
+#include <linux/mmu_notifier.h>
+#include <linux/highmem.h>
+#include <linux/page_idle.h>
+#include <linux/pagewalk.h>
+#include <linux/random.h>
+#include <linux/sched/mm.h>
+#include <linux/slab.h>
+
+#ifdef CONFIG_DAMON_VADDR_KUNIT_TEST
+#undef DAMON_MIN_REGION
+#define DAMON_MIN_REGION 1
+#endif
+
+/* Get a random number in [l, r) */
+#define damon_rand(l, r) (l + prandom_u32_max(r - l))
+
+/*
+ * 't->id' should be the pointer to the relevant 'struct pid' having reference
+ * count.  Caller must put the returned task, unless it is NULL.
+ */
+#define damon_get_task_struct(t) \
+	(get_pid_task((struct pid *)t->id, PIDTYPE_PID))
+
+/*
+ * Get the mm_struct of the given target
+ *
+ * Caller _must_ put the mm_struct after use, unless it is NULL.
+ *
+ * Returns the mm_struct of the target on success, NULL on failure
+ */
+static struct mm_struct *damon_get_mm(struct damon_target *t)
+{
+	struct task_struct *task;
+	struct mm_struct *mm;
+
+	task = damon_get_task_struct(t);
+	if (!task)
+		return NULL;
+
+	mm = get_task_mm(task);
+	put_task_struct(task);
+	return mm;
+}
+
+/*
+ * Functions for the initial monitoring target regions construction
+ */
+
+/*
+ * Size-evenly split a region into 'nr_pieces' small regions
+ *
+ * Returns 0 on success, or negative error code otherwise.
+ */
+static int damon_va_evenly_split_region(struct damon_target *t,
+		struct damon_region *r, unsigned int nr_pieces)
+{
+	unsigned long sz_orig, sz_piece, orig_end;
+	struct damon_region *n = NULL, *next;
+	unsigned long start;
+
+	if (!r || !nr_pieces)
+		return -EINVAL;
+
+	orig_end = r->ar.end;
+	sz_orig = r->ar.end - r->ar.start;
+	sz_piece = ALIGN_DOWN(sz_orig / nr_pieces, DAMON_MIN_REGION);
+
+	if (!sz_piece)
+		return -EINVAL;
+
+	r->ar.end = r->ar.start + sz_piece;
+	next = damon_next_region(r);
+	for (start = r->ar.end; start + sz_piece <= orig_end;
+			start += sz_piece) {
+		n = damon_new_region(start, start + sz_piece);
+		if (!n)
+			return -ENOMEM;
+		damon_insert_region(n, r, next, t);
+		r = n;
+	}
+	/* complement last region for possible rounding error */
+	if (n)
+		n->ar.end = orig_end;
+
+	return 0;
+}
+
+static unsigned long sz_range(struct damon_addr_range *r)
+{
+	return r->end - r->start;
+}
+
+static void swap_ranges(struct damon_addr_range *r1,
+			struct damon_addr_range *r2)
+{
+	struct damon_addr_range tmp;
+
+	tmp = *r1;
+	*r1 = *r2;
+	*r2 = tmp;
+}
+
+/*
+ * Find three regions separated by two biggest unmapped regions
+ *
+ * vma		the head vma of the target address space
+ * regions	an array of three address ranges that results will be saved
+ *
+ * This function receives an address space and finds three regions in it which
+ * separated by the two biggest unmapped regions in the space.  Please refer to
+ * below comments of '__damon_va_init_regions()' function to know why this is
+ * necessary.
+ *
+ * Returns 0 if success, or negative error code otherwise.
+ */
+static int __damon_va_three_regions(struct vm_area_struct *vma,
+				       struct damon_addr_range regions[3])
+{
+	struct damon_addr_range gap = {0}, first_gap = {0}, second_gap = {0};
+	struct vm_area_struct *last_vma = NULL;
+	unsigned long start = 0;
+	struct rb_root rbroot;
+
+	/* Find two biggest gaps so that first_gap > second_gap > others */
+	for (; vma; vma = vma->vm_next) {
+		if (!last_vma) {
+			start = vma->vm_start;
+			goto next;
+		}
+
+		if (vma->rb_subtree_gap <= sz_range(&second_gap)) {
+			rbroot.rb_node = &vma->vm_rb;
+			vma = rb_entry(rb_last(&rbroot),
+					struct vm_area_struct, vm_rb);
+			goto next;
+		}
+
+		gap.start = last_vma->vm_end;
+		gap.end = vma->vm_start;
+		if (sz_range(&gap) > sz_range(&second_gap)) {
+			swap_ranges(&gap, &second_gap);
+			if (sz_range(&second_gap) > sz_range(&first_gap))
+				swap_ranges(&second_gap, &first_gap);
+		}
+next:
+		last_vma = vma;
+	}
+
+	if (!sz_range(&second_gap) || !sz_range(&first_gap))
+		return -EINVAL;
+
+	/* Sort the two biggest gaps by address */
+	if (first_gap.start > second_gap.start)
+		swap_ranges(&first_gap, &second_gap);
+
+	/* Store the result */
+	regions[0].start = ALIGN(start, DAMON_MIN_REGION);
+	regions[0].end = ALIGN(first_gap.start, DAMON_MIN_REGION);
+	regions[1].start = ALIGN(first_gap.end, DAMON_MIN_REGION);
+	regions[1].end = ALIGN(second_gap.start, DAMON_MIN_REGION);
+	regions[2].start = ALIGN(second_gap.end, DAMON_MIN_REGION);
+	regions[2].end = ALIGN(last_vma->vm_end, DAMON_MIN_REGION);
+
+	return 0;
+}
+
+/*
+ * Get the three regions in the given target (task)
+ *
+ * Returns 0 on success, negative error code otherwise.
+ */
+static int damon_va_three_regions(struct damon_target *t,
+				struct damon_addr_range regions[3])
+{
+	struct mm_struct *mm;
+	int rc;
+
+	mm = damon_get_mm(t);
+	if (!mm)
+		return -EINVAL;
+
+	mmap_read_lock(mm);
+	rc = __damon_va_three_regions(mm->mmap, regions);
+	mmap_read_unlock(mm);
+
+	mmput(mm);
+	return rc;
+}
+
+/*
+ * Initialize the monitoring target regions for the given target (task)
+ *
+ * t	the given target
+ *
+ * Because only a number of small portions of the entire address space
+ * is actually mapped to the memory and accessed, monitoring the unmapped
+ * regions is wasteful.  That said, because we can deal with small noises,
+ * tracking every mapping is not strictly required but could even incur a high
+ * overhead if the mapping frequently changes or the number of mappings is
+ * high.  The adaptive regions adjustment mechanism will further help to deal
+ * with the noise by simply identifying the unmapped areas as a region that
+ * has no access.  Moreover, applying the real mappings that would have many
+ * unmapped areas inside will make the adaptive mechanism quite complex.  That
+ * said, too huge unmapped areas inside the monitoring target should be removed
+ * to not take the time for the adaptive mechanism.
+ *
+ * For the reason, we convert the complex mappings to three distinct regions
+ * that cover every mapped area of the address space.  Also the two gaps
+ * between the three regions are the two biggest unmapped areas in the given
+ * address space.  In detail, this function first identifies the start and the
+ * end of the mappings and the two biggest unmapped areas of the address space.
+ * Then, it constructs the three regions as below:
+ *
+ *     [mappings[0]->start, big_two_unmapped_areas[0]->start)
+ *     [big_two_unmapped_areas[0]->end, big_two_unmapped_areas[1]->start)
+ *     [big_two_unmapped_areas[1]->end, mappings[nr_mappings - 1]->end)
+ *
+ * As usual memory map of processes is as below, the gap between the heap and
+ * the uppermost mmap()-ed region, and the gap between the lowermost mmap()-ed
+ * region and the stack will be two biggest unmapped regions.  Because these
+ * gaps are exceptionally huge areas in usual address space, excluding these
+ * two biggest unmapped regions will be sufficient to make a trade-off.
+ *
+ *   <heap>
+ *   <BIG UNMAPPED REGION 1>
+ *   <uppermost mmap()-ed region>
+ *   (other mmap()-ed regions and small unmapped regions)
+ *   <lowermost mmap()-ed region>
+ *   <BIG UNMAPPED REGION 2>
+ *   <stack>
+ */
+static void __damon_va_init_regions(struct damon_ctx *ctx,
+				     struct damon_target *t)
+{
+	struct damon_region *r;
+	struct damon_addr_range regions[3];
+	unsigned long sz = 0, nr_pieces;
+	int i;
+
+	if (damon_va_three_regions(t, regions)) {
+		pr_err("Failed to get three regions of target %lu\n", t->id);
+		return;
+	}
+
+	for (i = 0; i < 3; i++)
+		sz += regions[i].end - regions[i].start;
+	if (ctx->min_nr_regions)
+		sz /= ctx->min_nr_regions;
+	if (sz < DAMON_MIN_REGION)
+		sz = DAMON_MIN_REGION;
+
+	/* Set the initial three regions of the target */
+	for (i = 0; i < 3; i++) {
+		r = damon_new_region(regions[i].start, regions[i].end);
+		if (!r) {
+			pr_err("%d'th init region creation failed\n", i);
+			return;
+		}
+		damon_add_region(r, t);
+
+		nr_pieces = (regions[i].end - regions[i].start) / sz;
+		damon_va_evenly_split_region(t, r, nr_pieces);
+	}
+}
+
+/* Initialize '->regions_list' of every target (task) */
+void damon_va_init(struct damon_ctx *ctx)
+{
+	struct damon_target *t;
+
+	damon_for_each_target(t, ctx) {
+		/* the user may set the target regions as they want */
+		if (!damon_nr_regions(t))
+			__damon_va_init_regions(ctx, t);
+	}
+}
+
+/*
+ * Functions for the dynamic monitoring target regions update
+ */
+
+/*
+ * Check whether a region is intersecting an address range
+ *
+ * Returns true if it is.
+ */
+static bool damon_intersect(struct damon_region *r, struct damon_addr_range *re)
+{
+	return !(r->ar.end <= re->start || re->end <= r->ar.start);
+}
+
+/*
+ * Update damon regions for the three big regions of the given target
+ *
+ * t		the given target
+ * bregions	the three big regions of the target
+ */
+static void damon_va_apply_three_regions(struct damon_target *t,
+		struct damon_addr_range bregions[3])
+{
+	struct damon_region *r, *next;
+	unsigned int i = 0;
+
+	/* Remove regions which are not in the three big regions now */
+	damon_for_each_region_safe(r, next, t) {
+		for (i = 0; i < 3; i++) {
+			if (damon_intersect(r, &bregions[i]))
+				break;
+		}
+		if (i == 3)
+			damon_destroy_region(r, t);
+	}
+
+	/* Adjust intersecting regions to fit with the three big regions */
+	for (i = 0; i < 3; i++) {
+		struct damon_region *first = NULL, *last;
+		struct damon_region *newr;
+		struct damon_addr_range *br;
+
+		br = &bregions[i];
+		/* Get the first and last regions which intersects with br */
+		damon_for_each_region(r, t) {
+			if (damon_intersect(r, br)) {
+				if (!first)
+					first = r;
+				last = r;
+			}
+			if (r->ar.start >= br->end)
+				break;
+		}
+		if (!first) {
+			/* no damon_region intersects with this big region */
+			newr = damon_new_region(
+					ALIGN_DOWN(br->start,
+						DAMON_MIN_REGION),
+					ALIGN(br->end, DAMON_MIN_REGION));
+			if (!newr)
+				continue;
+			damon_insert_region(newr, damon_prev_region(r), r, t);
+		} else {
+			first->ar.start = ALIGN_DOWN(br->start,
+					DAMON_MIN_REGION);
+			last->ar.end = ALIGN(br->end, DAMON_MIN_REGION);
+		}
+	}
+}
+
+/*
+ * Update regions for current memory mappings
+ */
+void damon_va_update(struct damon_ctx *ctx)
+{
+	struct damon_addr_range three_regions[3];
+	struct damon_target *t;
+
+	damon_for_each_target(t, ctx) {
+		if (damon_va_three_regions(t, three_regions))
+			continue;
+		damon_va_apply_three_regions(t, three_regions);
+	}
+}
+
+/*
+ * Get an online page for a pfn if it's in the LRU list.  Otherwise, returns
+ * NULL.
+ *
+ * The body of this function is stolen from the 'page_idle_get_page()'.  We
+ * steal rather than reuse it because the code is quite simple.
+ */
+static struct page *damon_get_page(unsigned long pfn)
+{
+	struct page *page = pfn_to_online_page(pfn);
+
+	if (!page || !PageLRU(page) || !get_page_unless_zero(page))
+		return NULL;
+
+	if (unlikely(!PageLRU(page))) {
+		put_page(page);
+		page = NULL;
+	}
+	return page;
+}
+
+static void damon_ptep_mkold(pte_t *pte, struct mm_struct *mm,
+			     unsigned long addr)
+{
+	bool referenced = false;
+	struct page *page = damon_get_page(pte_pfn(*pte));
+
+	if (!page)
+		return;
+
+	if (pte_young(*pte)) {
+		referenced = true;
+		*pte = pte_mkold(*pte);
+	}
+
+#ifdef CONFIG_MMU_NOTIFIER
+	if (mmu_notifier_clear_young(mm, addr, addr + PAGE_SIZE))
+		referenced = true;
+#endif /* CONFIG_MMU_NOTIFIER */
+
+	if (referenced)
+		set_page_young(page);
+
+	set_page_idle(page);
+	put_page(page);
+}
+
+static void damon_pmdp_mkold(pmd_t *pmd, struct mm_struct *mm,
+			     unsigned long addr)
+{
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	bool referenced = false;
+	struct page *page = damon_get_page(pmd_pfn(*pmd));
+
+	if (!page)
+		return;
+
+	if (pmd_young(*pmd)) {
+		referenced = true;
+		*pmd = pmd_mkold(*pmd);
+	}
+
+#ifdef CONFIG_MMU_NOTIFIER
+	if (mmu_notifier_clear_young(mm, addr,
+				addr + ((1UL) << HPAGE_PMD_SHIFT)))
+		referenced = true;
+#endif /* CONFIG_MMU_NOTIFIER */
+
+	if (referenced)
+		set_page_young(page);
+
+	set_page_idle(page);
+	put_page(page);
+#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
+}
+
+static int damon_mkold_pmd_entry(pmd_t *pmd, unsigned long addr,
+		unsigned long next, struct mm_walk *walk)
+{
+	pte_t *pte;
+	spinlock_t *ptl;
+
+	if (pmd_huge(*pmd)) {
+		ptl = pmd_lock(walk->mm, pmd);
+		if (pmd_huge(*pmd)) {
+			damon_pmdp_mkold(pmd, walk->mm, addr);
+			spin_unlock(ptl);
+			return 0;
+		}
+		spin_unlock(ptl);
+	}
+
+	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
+		return 0;
+	pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+	if (!pte_present(*pte))
+		goto out;
+	damon_ptep_mkold(pte, walk->mm, addr);
+out:
+	pte_unmap_unlock(pte, ptl);
+	return 0;
+}
+
+static struct mm_walk_ops damon_mkold_ops = {
+	.pmd_entry = damon_mkold_pmd_entry,
+};
+
+static void damon_va_mkold(struct mm_struct *mm, unsigned long addr)
+{
+	mmap_read_lock(mm);
+	walk_page_range(mm, addr, addr + 1, &damon_mkold_ops, NULL);
+	mmap_read_unlock(mm);
+}
+
+/*
+ * Functions for the access checking of the regions
+ */
+
+static void damon_va_prepare_access_check(struct damon_ctx *ctx,
+			struct mm_struct *mm, struct damon_region *r)
+{
+	r->sampling_addr = damon_rand(r->ar.start, r->ar.end);
+
+	damon_va_mkold(mm, r->sampling_addr);
+}
+
+void damon_va_prepare_access_checks(struct damon_ctx *ctx)
+{
+	struct damon_target *t;
+	struct mm_struct *mm;
+	struct damon_region *r;
+
+	damon_for_each_target(t, ctx) {
+		mm = damon_get_mm(t);
+		if (!mm)
+			continue;
+		damon_for_each_region(r, t)
+			damon_va_prepare_access_check(ctx, mm, r);
+		mmput(mm);
+	}
+}
+
+struct damon_young_walk_private {
+	unsigned long *page_sz;
+	bool young;
+};
+
+static int damon_young_pmd_entry(pmd_t *pmd, unsigned long addr,
+		unsigned long next, struct mm_walk *walk)
+{
+	pte_t *pte;
+	spinlock_t *ptl;
+	struct page *page;
+	struct damon_young_walk_private *priv = walk->private;
+
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+	if (pmd_huge(*pmd)) {
+		ptl = pmd_lock(walk->mm, pmd);
+		if (!pmd_huge(*pmd)) {
+			spin_unlock(ptl);
+			goto regular_page;
+		}
+		page = damon_get_page(pmd_pfn(*pmd));
+		if (!page)
+			goto huge_out;
+		if (pmd_young(*pmd) || !page_is_idle(page) ||
+					mmu_notifier_test_young(walk->mm,
+						addr)) {
+			*priv->page_sz = ((1UL) << HPAGE_PMD_SHIFT);
+			priv->young = true;
+		}
+		put_page(page);
+huge_out:
+		spin_unlock(ptl);
+		return 0;
+	}
+
+regular_page:
+#endif	/* CONFIG_TRANSPARENT_HUGEPAGE */
+
+	if (pmd_none(*pmd) || unlikely(pmd_bad(*pmd)))
+		return -EINVAL;
+	pte = pte_offset_map_lock(walk->mm, pmd, addr, &ptl);
+	if (!pte_present(*pte))
+		goto out;
+	page = damon_get_page(pte_pfn(*pte));
+	if (!page)
+		goto out;
+	if (pte_young(*pte) || !page_is_idle(page) ||
+			mmu_notifier_test_young(walk->mm, addr)) {
+		*priv->page_sz = PAGE_SIZE;
+		priv->young = true;
+	}
+	put_page(page);
+out:
+	pte_unmap_unlock(pte, ptl);
+	return 0;
+}
+
+static struct mm_walk_ops damon_young_ops = {
+	.pmd_entry = damon_young_pmd_entry,
+};
+
+static bool damon_va_young(struct mm_struct *mm, unsigned long addr,
+		unsigned long *page_sz)
+{
+	struct damon_young_walk_private arg = {
+		.page_sz = page_sz,
+		.young = false,
+	};
+
+	mmap_read_lock(mm);
+	walk_page_range(mm, addr, addr + 1, &damon_young_ops, &arg);
+	mmap_read_unlock(mm);
+	return arg.young;
+}
+
+/*
+ * Check whether the region was accessed after the last preparation
+ *
+ * mm	'mm_struct' for the given virtual address space
+ * r	the region to be checked
+ */
+static void damon_va_check_access(struct damon_ctx *ctx,
+			       struct mm_struct *mm, struct damon_region *r)
+{
+	static struct mm_struct *last_mm;
+	static unsigned long last_addr;
+	static unsigned long last_page_sz = PAGE_SIZE;
+	static bool last_accessed;
+
+	/* If the region is in the last checked page, reuse the result */
+	if (mm == last_mm && (ALIGN_DOWN(last_addr, last_page_sz) ==
+				ALIGN_DOWN(r->sampling_addr, last_page_sz))) {
+		if (last_accessed)
+			r->nr_accesses++;
+		return;
+	}
+
+	last_accessed = damon_va_young(mm, r->sampling_addr, &last_page_sz);
+	if (last_accessed)
+		r->nr_accesses++;
+
+	last_mm = mm;
+	last_addr = r->sampling_addr;
+}
+
+unsigned int damon_va_check_accesses(struct damon_ctx *ctx)
+{
+	struct damon_target *t;
+	struct mm_struct *mm;
+	struct damon_region *r;
+	unsigned int max_nr_accesses = 0;
+
+	damon_for_each_target(t, ctx) {
+		mm = damon_get_mm(t);
+		if (!mm)
+			continue;
+		damon_for_each_region(r, t) {
+			damon_va_check_access(ctx, mm, r);
+			max_nr_accesses = max(r->nr_accesses, max_nr_accesses);
+		}
+		mmput(mm);
+	}
+
+	return max_nr_accesses;
+}
+
+/*
+ * Functions for the target validity check and cleanup
+ */
+
+bool damon_va_target_valid(void *target)
+{
+	struct damon_target *t = target;
+	struct task_struct *task;
+
+	task = damon_get_task_struct(t);
+	if (task) {
+		put_task_struct(task);
+		return true;
+	}
+
+	return false;
+}
+
+void damon_va_set_primitives(struct damon_ctx *ctx)
+{
+	ctx->primitive.init = damon_va_init;
+	ctx->primitive.update = damon_va_update;
+	ctx->primitive.prepare_access_checks = damon_va_prepare_access_checks;
+	ctx->primitive.check_accesses = damon_va_check_accesses;
+	ctx->primitive.reset_aggregated = NULL;
+	ctx->primitive.target_valid = damon_va_target_valid;
+	ctx->primitive.cleanup = NULL;
+}
+
+#include "vaddr-test.h"

mm/early_ioremap.c

···
 	return prot;
 }
 
-void __init __weak early_ioremap_shutdown(void)
-{
-}
-
 void __init early_ioremap_reset(void)
 {
-	early_ioremap_shutdown();
 	after_paging_init = 1;
 }
 

mm/highmem.c

···
 
 static inline int kmap_local_idx_push(void)
 {
-	WARN_ON_ONCE(in_irq() && !irqs_disabled());
+	WARN_ON_ONCE(in_hardirq() && !irqs_disabled());
 	current->kmap_ctrl.idx += KM_INCR;
 	BUG_ON(current->kmap_ctrl.idx >= KM_MAX_IDX);
 	return current->kmap_ctrl.idx - 1;

mm/ioremap.c

···
  */
 #include <linux/vmalloc.h>
 #include <linux/mm.h>
-#include <linux/sched.h>
 #include <linux/io.h>
 #include <linux/export.h>
-#include <asm/cacheflush.h>
 
-#include "pgalloc-track.h"
-
-#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
-static unsigned int __ro_after_init iomap_max_page_shift = BITS_PER_LONG - 1;
-
-static int __init set_nohugeiomap(char *str)
-{
-	iomap_max_page_shift = PAGE_SHIFT;
-	return 0;
-}
-early_param("nohugeiomap", set_nohugeiomap);
-#else /* CONFIG_HAVE_ARCH_HUGE_VMAP */
-static const unsigned int iomap_max_page_shift = PAGE_SHIFT;
-#endif	/* CONFIG_HAVE_ARCH_HUGE_VMAP */
-
-int ioremap_page_range(unsigned long addr,
-		       unsigned long end, phys_addr_t phys_addr, pgprot_t prot)
-{
-	return vmap_range(addr, end, phys_addr, prot, iomap_max_page_shift);
-}
-
-#ifdef CONFIG_GENERIC_IOREMAP
 void __iomem *ioremap_prot(phys_addr_t addr, size_t size, unsigned long prot)
 {
 	unsigned long offset, vaddr;
···
 	vunmap((void *)((unsigned long)addr & PAGE_MASK));
 }
 EXPORT_SYMBOL(iounmap);
-#endif /* CONFIG_GENERIC_IOREMAP */

mm/kfence/core.c

···
 #include <linux/moduleparam.h>
 #include <linux/random.h>
 #include <linux/rcupdate.h>
+#include <linux/sched/clock.h>
 #include <linux/sched/sysctl.h>
 #include <linux/seq_file.h>
 #include <linux/slab.h>
···
 	 */
 	track->num_stack_entries = stack_trace_save(track->stack_entries, KFENCE_STACK_DEPTH, 1);
 	track->pid = task_pid_nr(current);
+	track->cpu = raw_smp_processor_id();
+	track->ts_nsec = local_clock(); /* Same source as printk timestamps. */
 
 	/*
 	 * Pairs with READ_ONCE() in

mm/kfence/kfence.h

···
 /* Alloc/free tracking information. */
 struct kfence_track {
 	pid_t pid;
+	int cpu;
+	u64 ts_nsec;
 	int num_stack_entries;
 	unsigned long stack_entries[KFENCE_STACK_DEPTH];
 };

mm/kfence/kfence_test.c

···
 	unsigned long flags;
 	int i;
 
+	if (!__kfence_pool)
+		return -EINVAL;
+
 	spin_lock_irqsave(&observed.lock, flags);
 	for (i = 0; i < ARRAY_SIZE(observed.lines); i++)
 		observed.lines[i][0] = '\0';

mm/kfence/report.c

···
 
 #include <linux/kernel.h>
 #include <linux/lockdep.h>
+#include <linux/math.h>
 #include <linux/printk.h>
 #include <linux/sched/debug.h>
 #include <linux/seq_file.h>
···
 			       bool show_alloc)
 {
 	const struct kfence_track *track = show_alloc ? &meta->alloc_track : &meta->free_track;
+	u64 ts_sec = track->ts_nsec;
+	unsigned long rem_nsec = do_div(ts_sec, NSEC_PER_SEC);
+
+	/* Timestamp matches printk timestamp format. */
+	seq_con_printf(seq, "%s by task %d on cpu %d at %lu.%06lus:\n",
+		       show_alloc ? "allocated" : "freed", track->pid,
+		       track->cpu, (unsigned long)ts_sec, rem_nsec / 1000);
 
 	if (track->num_stack_entries) {
 		/* Skip allocation/free internals stack. */
···
 		return;
 	}
 
-	seq_con_printf(seq,
-		       "kfence-#%td [0x%p-0x%p"
-		       ", size=%d, cache=%s] allocated by task %d:\n",
-		       meta - kfence_metadata, (void *)start, (void *)(start + size - 1), size,
-		       (cache && cache->name) ? cache->name : "<destroyed>", meta->alloc_track.pid);
+	seq_con_printf(seq, "kfence-#%td: 0x%p-0x%p, size=%d, cache=%s\n\n",
+		       meta - kfence_metadata, (void *)start, (void *)(start + size - 1),
+		       size, (cache && cache->name) ? cache->name : "<destroyed>");
+
 	kfence_print_stack(seq, meta, true);
 
 	if (meta->state == KFENCE_OBJECT_FREED) {
-		seq_con_printf(seq, "\nfreed by task %d:\n", meta->free_track.pid);
+		seq_con_printf(seq, "\n");
 		kfence_print_stack(seq, meta, false);
 	}
 }

mm/kmemleak.c

···
 	object->checksum = 0;
 
 	/* task information */
-	if (in_irq()) {
+	if (in_hardirq()) {
 		object->pid = 0;
 		strncpy(object->comm, "hardirq", sizeof(object->comm));
 	} else if (in_serving_softirq()) {

mm/memory_hotplug.c

···
 MODULE_PARM_DESC(memmap_on_memory, "Enable memmap on memory for memory hotplug");
 #endif
 
+enum {
+	ONLINE_POLICY_CONTIG_ZONES = 0,
+	ONLINE_POLICY_AUTO_MOVABLE,
+};
+
+const char *online_policy_to_str[] = {
+	[ONLINE_POLICY_CONTIG_ZONES] = "contig-zones",
+	[ONLINE_POLICY_AUTO_MOVABLE] = "auto-movable",
+};
+
+static int set_online_policy(const char *val, const struct kernel_param *kp)
+{
+	int ret = sysfs_match_string(online_policy_to_str, val);
+
+	if (ret < 0)
+		return ret;
+	*((int *)kp->arg) = ret;
+	return 0;
+}
+
+static int get_online_policy(char *buffer, const struct kernel_param *kp)
+{
+	return sprintf(buffer, "%s\n", online_policy_to_str[*((int *)kp->arg)]);
+}
+
+/*
+ * memory_hotplug.online_policy: configure online behavior when onlining without
+ * specifying a zone (MMOP_ONLINE)
+ *
+ * "contig-zones": keep zone contiguous
+ * "auto-movable": online memory to ZONE_MOVABLE if the configuration
+ *                 (auto_movable_ratio, auto_movable_numa_aware) allows for it
+ */
+static int online_policy __read_mostly = ONLINE_POLICY_CONTIG_ZONES;
+static const struct kernel_param_ops online_policy_ops = {
+	.set = set_online_policy,
+	.get = get_online_policy,
+};
+module_param_cb(online_policy, &online_policy_ops, &online_policy, 0644);
+MODULE_PARM_DESC(online_policy,
+		"Set the online policy (\"contig-zones\", \"auto-movable\") "
+		"Default: \"contig-zones\"");
+
+/*
+ * memory_hotplug.auto_movable_ratio: specify maximum MOVABLE:KERNEL ratio
+ *
+ * The ratio represent an upper limit and the kernel might decide to not
+ * online some memory to ZONE_MOVABLE -- e.g., because hotplugged KERNEL memory
+ * doesn't allow for more MOVABLE memory.
+ */
+static unsigned int auto_movable_ratio __read_mostly = 301;
+module_param(auto_movable_ratio, uint, 0644);
+MODULE_PARM_DESC(auto_movable_ratio,
+		"Set the maximum ratio of MOVABLE:KERNEL memory in the system "
+		"in percent for \"auto-movable\" online policy. Default: 301");
+
+/*
+ * memory_hotplug.auto_movable_numa_aware: consider numa node stats
+ */
+#ifdef CONFIG_NUMA
+static bool auto_movable_numa_aware __read_mostly = true;
+module_param(auto_movable_numa_aware, bool, 0644);
+MODULE_PARM_DESC(auto_movable_numa_aware,
+		"Consider numa node stats in addition to global stats in "
+		"\"auto-movable\" online policy. Default: true");
+#endif /* CONFIG_NUMA */
+
 /*
  * online_page_callback contains pointer to current page onlining function.
  * Initially it is generic_online_page(). If it is required it could be
···
 				 sizeof(struct page) * cur_nr_pages);
 	}
 
-#ifdef CONFIG_ZONE_DEVICE
 	/*
 	 * Zone shrinking code cannot properly deal with ZONE_DEVICE. So
 	 * we will not try to shrink the zones - which is okay as
 	 * set_zone_contiguous() cannot deal with ZONE_DEVICE either way.
 	 */
-	if (zone_idx(zone) == ZONE_DEVICE)
+	if (zone_is_zone_device(zone))
 		return;
-#endif
 
 	clear_zone_contiguous(zone);
 
···
 	set_zone_contiguous(zone);
 }
 
+struct auto_movable_stats {
+	unsigned long kernel_early_pages;
+	unsigned long movable_pages;
+};
+
+static void auto_movable_stats_account_zone(struct auto_movable_stats *stats,
+					    struct zone *zone)
+{
+	if (zone_idx(zone) == ZONE_MOVABLE) {
+		stats->movable_pages += zone->present_pages;
+	} else {
+		stats->kernel_early_pages += zone->present_early_pages;
+#ifdef CONFIG_CMA
+		/*
+		 * CMA pages (never on hotplugged memory) behave like
+		 * ZONE_MOVABLE.
+		 */
+		stats->movable_pages += zone->cma_pages;
+		stats->kernel_early_pages -= zone->cma_pages;
+#endif /* CONFIG_CMA */
+	}
+}
+struct auto_movable_group_stats {
+	unsigned long movable_pages;
+	unsigned long req_kernel_early_pages;
+};
+
+static int auto_movable_stats_account_group(struct memory_group *group,
+					   void *arg)
+{
+	const int ratio = READ_ONCE(auto_movable_ratio);
+	struct auto_movable_group_stats *stats = arg;
+	long pages;
+
+	/*
+	 * We don't support modifying the config while the auto-movable online
+	 * policy is already enabled. Just avoid the division by zero below.
+	 */
+	if (!ratio)
+		return 0;
+
+	/*
+	 * Calculate how many early kernel pages this group requires to
+	 * satisfy the configured zone ratio.
+	 */
+	pages = group->present_movable_pages * 100 / ratio;
+	pages -= group->present_kernel_pages;
+
+	if (pages > 0)
+		stats->req_kernel_early_pages += pages;
+	stats->movable_pages += group->present_movable_pages;
+	return 0;
+}
+
+static bool auto_movable_can_online_movable(int nid, struct memory_group *group,
+					    unsigned long nr_pages)
+{
+	unsigned long kernel_early_pages, movable_pages;
+	struct auto_movable_group_stats group_stats = {};
+	struct auto_movable_stats stats = {};
+	pg_data_t *pgdat = NODE_DATA(nid);
+	struct zone *zone;
+	int i;
+
+	/* Walk all relevant zones and collect MOVABLE vs. KERNEL stats. */
+	if (nid == NUMA_NO_NODE) {
+		/* TODO: cache values */
+		for_each_populated_zone(zone)
+			auto_movable_stats_account_zone(&stats, zone);
+	} else {
+		for (i = 0; i < MAX_NR_ZONES; i++) {
+			zone = pgdat->node_zones + i;
+			if (populated_zone(zone))
+				auto_movable_stats_account_zone(&stats, zone);
+		}
+	}
+
+	kernel_early_pages = stats.kernel_early_pages;
+	movable_pages = stats.movable_pages;
+
+	/*
+	 * Kernel memory inside dynamic memory group allows for more MOVABLE
+	 * memory within the same group. Remove the effect of all but the
+	 * current group from the stats.
+	 */
+	walk_dynamic_memory_groups(nid, auto_movable_stats_account_group,
+				   group, &group_stats);
+	if (kernel_early_pages <= group_stats.req_kernel_early_pages)
+		return false;
+	kernel_early_pages -= group_stats.req_kernel_early_pages;
+	movable_pages -= group_stats.movable_pages;
+
+	if (group && group->is_dynamic)
+		kernel_early_pages += group->present_kernel_pages;
+
+	/*
+	 * Test if we could online the given number of pages to ZONE_MOVABLE
+	 * and still stay in the configured ratio.
+	 */
+	movable_pages += nr_pages;
+	return movable_pages <= (auto_movable_ratio * kernel_early_pages) / 100;
+}
+
 /*
  * Returns a default kernel memory zone for the given pfn range.
  * If no kernel zone covers this pfn range it will automatically go
···
 	}
 
 	return &pgdat->node_zones[ZONE_NORMAL];
+}
+
+/*
+ * Determine to which zone to online memory dynamically based on user
+ * configuration and system stats. We care about the following ratio:
+ *
+ *   MOVABLE : KERNEL
+ *
+ * Whereby MOVABLE is memory in ZONE_MOVABLE and KERNEL is memory in
+ * one of the kernel zones. CMA pages inside one of the kernel zones really
+ * behaves like ZONE_MOVABLE, so we treat them accordingly.
+ *
+ * We don't allow for hotplugged memory in a KERNEL zone to increase the
+ * amount of MOVABLE memory we can have, so we end up with:
+ *
+ *   MOVABLE : KERNEL_EARLY
+ *
+ * Whereby KERNEL_EARLY is memory in one of the kernel zones, available sinze
+ * boot. We base our calculation on KERNEL_EARLY internally, because:
+ *
+ * a) Hotplugged memory in one of the kernel zones can sometimes still get
+ *    hotunplugged, especially when hot(un)plugging individual memory blocks.
+ *    There is no coordination across memory devices, therefore "automatic"
+ *    hotunplugging, as implemented in hypervisors, could result in zone
+ *    imbalances.
+ * b) Early/boot memory in one of the kernel zones can usually not get
+ *    hotunplugged again (e.g., no firmware interface to unplug, fragmented
+ *    with unmovable allocations). While there are corner cases where it might
+ *    still work, it is barely relevant in practice.
+ *
+ * Exceptions are dynamic memory groups, which allow for more MOVABLE
+ * memory within the same memory group -- because in that case, there is
+ * coordination within the single memory device managed by a single driver.
+ *
+ * We rely on "present pages" instead of "managed pages", as the latter is
+ * highly unreliable and dynamic in virtualized environments, and does not
+ * consider boot time allocations. For example, memory ballooning adjusts the
+ * managed pages when inflating/deflating the balloon, and balloon compaction
+ * can even migrate inflated pages between zones.
+ *
+ * Using "present pages" is better but some things to keep in mind are:
+ *
+ * a) Some memblock allocations, such as for the crashkernel area, are
+ *    effectively unused by the kernel, yet they account to "present pages".
+ *    Fortunately, these allocations are comparatively small in relevant setups
+ *    (e.g., fraction of system memory).
+ * b) Some hotplugged memory blocks in virtualized environments, esecially
+ *    hotplugged by virtio-mem, look like they are completely present, however,
+ *    only parts of the memory block are actually currently usable.
+ *    "present pages" is an upper limit that can get reached at runtime. As
+ *    we base our calculations on KERNEL_EARLY, this is not an issue.
+ */
+static struct zone *auto_movable_zone_for_pfn(int nid,
+					      struct memory_group *group,
+					      unsigned long pfn,
+					      unsigned long nr_pages)
+{
+	unsigned long online_pages = 0, max_pages, end_pfn;
+	struct page *page;
+
+	if (!auto_movable_ratio)
+		goto kernel_zone;
+
+	if (group && !group->is_dynamic) {
+		max_pages = group->s.max_pages;
+		online_pages = group->present_movable_pages;
+
+		/* If anything is !MOVABLE online the rest !MOVABLE. */
+		if (group->present_kernel_pages)
+			goto kernel_zone;
+	} else if (!group || group->d.unit_pages == nr_pages) {
+		max_pages = nr_pages;
+	} else {
+		max_pages = group->d.unit_pages;
+		/*
+		 * Take a look at all online sections in the current unit.
+		 * We can safely assume that all pages within a section belong
+		 * to the same zone, because dynamic memory groups only deal
+		 * with hotplugged memory.
+		 */
+		pfn = ALIGN_DOWN(pfn, group->d.unit_pages);
+		end_pfn = pfn + group->d.unit_pages;
+		for (; pfn < end_pfn; pfn += PAGES_PER_SECTION) {
+			page = pfn_to_online_page(pfn);
+			if (!page)
+				continue;
+			/* If anything is !MOVABLE online the rest !MOVABLE. */
+			if (page_zonenum(page) != ZONE_MOVABLE)
+				goto kernel_zone;
+			online_pages += PAGES_PER_SECTION;
+		}
+	}
+
+	/*
+	 * Online MOVABLE if we could *currently* online all remaining parts
+	 * MOVABLE. We expect to (add+) online them immediately next, so if
+	 * nobody interferes, all will be MOVABLE if possible.
+	 */
+	nr_pages = max_pages - online_pages;
+	if (!auto_movable_can_online_movable(NUMA_NO_NODE, group, nr_pages))
+		goto kernel_zone;
+
+#ifdef CONFIG_NUMA
+	if (auto_movable_numa_aware &&
+	    !auto_movable_can_online_movable(nid, group, nr_pages))
+		goto kernel_zone;
+#endif /* CONFIG_NUMA */
+
+	return &NODE_DATA(nid)->node_zones[ZONE_MOVABLE];
+kernel_zone:
+	return default_kernel_zone_for_pfn(nid, pfn, nr_pages);
 }
 
 static inline struct zone *default_zone_for_pfn(int nid, unsigned long start_pfn,
···
 	return movable_node_enabled ? movable_zone : kernel_zone;
 }
 
-struct zone *zone_for_pfn_range(int online_type, int nid, unsigned start_pfn,
+struct zone *zone_for_pfn_range(int online_type, int nid,
+		struct memory_group *group, unsigned long start_pfn,
 		unsigned long nr_pages)
 {
 	if (online_type == MMOP_ONLINE_KERNEL)
···
 	if (online_type == MMOP_ONLINE_MOVABLE)
 		return &NODE_DATA(nid)->node_zones[ZONE_MOVABLE];
 
+	if (online_policy == ONLINE_POLICY_AUTO_MOVABLE)
+		return auto_movable_zone_for_pfn(nid, group, start_pfn, nr_pages);
+
 	return default_zone_for_pfn(nid, start_pfn, nr_pages);
 }
 
···
  * This function should only be called by memory_block_{online,offline},
  * and {online,offline}_pages.
  */
-void adjust_present_page_count(struct zone *zone, long nr_pages)
+void adjust_present_page_count(struct page *page, struct memory_group *group,
+			       long nr_pages)
 {
+	struct zone *zone = page_zone(page);
+	const bool movable = zone_idx(zone) == ZONE_MOVABLE;
+
+	/*
+	 * We only support onlining/offlining/adding/removing of complete
+	 * memory blocks; therefore, either all is either early or hotplugged.
+	 */
+	if (early_section(__pfn_to_section(page_to_pfn(page))))
+		zone->present_early_pages += nr_pages;
 	zone->present_pages += nr_pages;
 	zone->zone_pgdat->node_present_pages += nr_pages;
+
+	if (group && movable)
+		group->present_movable_pages += nr_pages;
+	else if (group && !movable)
+		group->present_kernel_pages += nr_pages;
 }
 
 int mhp_init_memmap_on_memory(unsigned long pfn, unsigned long nr_pages,
···
 	kasan_remove_zero_shadow(__va(PFN_PHYS(pfn)), PFN_PHYS(nr_pages));
 }
 
-int __ref online_pages(unsigned long pfn, unsigned long nr_pages, struct zone *zone)
+int __ref online_pages(unsigned long pfn, unsigned long nr_pages,
+		       struct zone *zone, struct memory_group *group)
 {
 	unsigned long flags;
 	int need_zonelists_rebuild = 0;
···
 	}
 
 	online_pages_range(pfn, nr_pages);
-	adjust_present_page_count(zone, nr_pages);
+	adjust_present_page_count(pfn_to_page(pfn), group, nr_pages);
 
 	node_states_set_node(nid, &arg);
 	if (need_zonelists_rebuild)
···
 {
 	struct mhp_params params = { .pgprot = pgprot_mhp(PAGE_KERNEL) };
 	struct vmem_altmap mhp_altmap = {};
+	struct memory_group *group = NULL;
 	u64 start, size;
 	bool new_node = false;
 	int ret;
···
 	ret = check_hotplug_memory_range(start, size);
 	if (ret)
 		return ret;
+
+	if (mhp_flags & MHP_NID_IS_MGID) {
+		group = memory_group_find_by_id(nid);
+		if (!group)
+			return -EINVAL;
+		nid = group->nid;
+	}
 
 	if (!node_possible(nid)) {
 		WARN(1, "node %d was absent from the node_possible_map\n", nid);
···
 		goto error;
 
 	/* create memory block devices after memory was added */
-	ret = create_memory_block_devices(start, size, mhp_altmap.alloc);
+	ret = create_memory_block_devices(start, size, mhp_altmap.alloc,
+					  group);
 	if (ret) {
-		arch_remove_memory(nid, start, size, NULL);
+		arch_remove_memory(start, size, NULL);
 		goto error;
 	}
 
···
 	unsigned long pfn, sec_end_pfn;
 	struct zone *zone = NULL;
 	struct page *page;
-	int i;
+
 	for (pfn = start_pfn, sec_end_pfn = SECTION_ALIGN_UP(start_pfn + 1);
 	     pfn < end_pfn;
 	     pfn = sec_end_pfn, sec_end_pfn += PAGES_PER_SECTION) {
···
 			continue;
 		for (; pfn < sec_end_pfn && pfn < end_pfn;
 		     pfn += MAX_ORDER_NR_PAGES) {
-			i = 0;
-			/* This is just a CONFIG_HOLES_IN_ZONE check.*/
-			while ((i < MAX_ORDER_NR_PAGES) &&
-				!pfn_valid_within(pfn + i))
-				i++;
-			if (i == MAX_ORDER_NR_PAGES || pfn + i >= end_pfn)
-				continue;
 			/* Check if we got outside of the zone */
-			if (zone && !zone_spans_pfn(zone, pfn + i))
+			if (zone && !zone_spans_pfn(zone, pfn))
 				return NULL;
-			page = pfn_to_page(pfn + i);
+			page = pfn_to_page(pfn);
 			if (zone && page_zone(page) != zone)
 				return NULL;
 			zone = page_zone(page);
···
 	return 0;
 }
 
-int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages)
+int __ref offline_pages(unsigned long start_pfn, unsigned long nr_pages,
+			struct memory_group *group)
 {
 	const unsigned long end_pfn = start_pfn + nr_pages;
 	unsigned long pfn, system_ram_pages = 0;
···
 
 	/* removal success */
 	adjust_managed_page_count(pfn_to_page(start_pfn), -nr_pages);
-	adjust_present_page_count(zone, -nr_pages);
+	adjust_present_page_count(pfn_to_page(start_pfn), group, -nr_pages);
 
 	/* reinitialise watermarks and update pcp limits */
 	init_per_zone_wmark_min();
···
 static int check_memblock_offlined_cb(struct memory_block *mem, void *arg)
 {
 	int ret = !is_memblock_offlined(mem);
+	int *nid = arg;
 
+	*nid = mem->nid;
 	if (unlikely(ret)) {
 		phys_addr_t beginpa, endpa;
 
···
 }
 EXPORT_SYMBOL(try_offline_node);
 
-static int __ref try_remove_memory(int nid, u64 start, u64 size)
+static int __ref try_remove_memory(u64 start, u64 size)
 {
-	int rc = 0;
 	struct vmem_altmap mhp_altmap = {};
 	struct vmem_altmap *altmap = NULL;
 	unsigned long nr_vmemmap_pages;
+	int rc = 0, nid = NUMA_NO_NODE;
 
 	BUG_ON(check_hotplug_memory_range(start, size));
 
···
 	 * All memory blocks must be offlined before removing memory.  Check
 	 * whether all memory blocks in question are offline and return error
 	 * if this is not the case.
+	 *
+	 * While at it, determine the nid. Note that if we'd have mixed nodes,
+	 * we'd only try to offline the last determined one -- which is good
+	 * enough for the cases we care about.
 	 */
-	rc = walk_memory_blocks(start, size, NULL, check_memblock_offlined_cb);
+	rc = walk_memory_blocks(start, size, &nid, check_memblock_offlined_cb);
 	if (rc)
 		return rc;
 
···
 
 	mem_hotplug_begin();
 
-	arch_remove_memory(nid, start, size, altmap);
+	arch_remove_memory(start, size, altmap);
 
 	if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) {
 		memblock_free(start, size);
···
 
 	release_mem_region_adjustable(start, size);
 
-	try_offline_node(nid);
+	if (nid != NUMA_NO_NODE)
+		try_offline_node(nid);
 
 	mem_hotplug_done();
 	return 0;
···
 
 /**
  * __remove_memory - Remove memory if every memory block is offline
- * @nid: the node ID
  * @start: physical address of the region to remove
  * @size: size of the region to remove
  *
···
  * and online/offline operations before this call, as required by
  * try_offline_node().
  */
-void __remove_memory(int nid, u64 start, u64 size)
+void __remove_memory(u64 start, u64 size)
 {
 
 	/*
 	 * trigger BUG() if some memory is not offlined prior to calling this
 	 * function
 	 */
-	if (try_remove_memory(nid, start, size))
+	if (try_remove_memory(start, size))
 		BUG();
 }
 
···
  * Remove memory if every memory block is offline, otherwise return -EBUSY is
  * some memory is not offline
  */
-int remove_memory(int nid, u64 start, u64 size)
+int remove_memory(u64 start, u64 size)
 {
 	int rc;
 
 	lock_device_hotplug();
-	rc  = try_remove_memory(nid, start, size);
+	rc = try_remove_memory(start, size);
 	unlock_device_hotplug();
 
 	return rc;
···
  * unplugged all memory (so it's no longer in use) and want to offline + remove
  * that memory.
  */
-int offline_and_remove_memory(int nid, u64 start, u64 size)
+int offline_and_remove_memory(u64 start, u64 size)
 {
 	const unsigned long mb_count = size / memory_block_size_bytes();
 	uint8_t *online_types, *tmp;
···
 	 * This cannot fail as it cannot get onlined in the meantime.
 	 */
 	if (!rc) {
-		rc = try_remove_memory(nid, start, size);
+		rc = try_remove_memory(start, size);
 		if (rc)
 			pr_err("%s: Failed to remove memory: %d", __func__, rc);
 	}

mm/memremap.c

···
 {
 	struct range *range = &pgmap->ranges[range_id];
 	struct page *first_page;
-	int nid;
 
 	/* make sure to access a memmap that was actually initialized */
 	first_page = pfn_to_page(pfn_first(pgmap, range_id));
 
 	/* pages are dead and unused, undo the arch mapping */
-	nid = page_to_nid(first_page);
-
 	mem_hotplug_begin();
 	remove_pfn_range_from_zone(page_zone(first_page), PHYS_PFN(range->start),
 				   PHYS_PFN(range_len(range)));
···
 		__remove_pages(PHYS_PFN(range->start),
 			       PHYS_PFN(range_len(range)), NULL);
 	} else {
-		arch_remove_memory(nid, range->start, range_len(range),
+		arch_remove_memory(range->start, range_len(range),
 				pgmap_altmap(pgmap));
 		kasan_remove_zero_shadow(__va(range->start), range_len(range));
 	}

mm/page_alloc.c

···
 
 static int page_is_consistent(struct zone *zone, struct page *page)
 {
-	if (!pfn_valid_within(page_to_pfn(page)))
-		return 0;
 	if (zone != page_zone(page))
 		return 0;
 
···
 	if (order >= MAX_ORDER - 2)
 		return false;
 
-	if (!pfn_valid_within(buddy_pfn))
-		return false;
-
 	combined_pfn = buddy_pfn & pfn;
 	higher_page = page + (combined_pfn - pfn);
 	buddy_pfn = __find_buddy_pfn(combined_pfn, order + 1);
 	higher_buddy = higher_page + (buddy_pfn - combined_pfn);
 
-	return pfn_valid_within(buddy_pfn) &&
-	       page_is_buddy(higher_page, higher_buddy, order + 1);
+	return page_is_buddy(higher_page, higher_buddy, order + 1);
 }
 
 /*
···
 		buddy_pfn = __find_buddy_pfn(pfn, order);
 		buddy = page + (buddy_pfn - pfn);
 
-		if (!pfn_valid_within(buddy_pfn))
-			goto done_merging;
 		if (!page_is_buddy(page, buddy, order))
 			goto done_merging;
 		/*
···
 /*
  * Check that the whole (or subset of) a pageblock given by the interval of
  * [start_pfn, end_pfn) is valid and within the same zone, before scanning it
- * with the migration of free compaction scanner. The scanners then need to
- * use only pfn_valid_within() check for arches that allow holes within
- * pageblocks.
+ * with the migration of free compaction scanner.
  *
  * Return struct page pointer of start_pfn, or NULL if checks were not passed.
  *
···
  */
 static inline bool __init deferred_pfn_valid(unsigned long pfn)
 {
-	if (!pfn_valid_within(pfn))
-		return false;
 	if (!(pfn & (pageblock_nr_pages - 1)) && !pfn_valid(pfn))
 		return false;
 	return true;
···
 	int pages_moved = 0;
 
 	for (pfn = start_pfn; pfn <= end_pfn;) {
-		if (!pfn_valid_within(pfn)) {
-			pfn++;
-			continue;
-		}
-
 		page = pfn_to_page(pfn);
 		if (!PageBuddy(page)) {
 			/*
···
 			zone->zone_start_pfn = 0;
 		zone->spanned_pages = size;
 		zone->present_pages = real_size;
+#if defined(CONFIG_MEMORY_HOTPLUG)
+		zone->present_early_pages = real_size;
+#endif
 
 		totalpages += size;
 		realtotalpages += real_size;
···
 	}
 
 	for (; iter < pageblock_nr_pages - offset; iter++) {
-		if (!pfn_valid_within(pfn + iter))
-			continue;
-
 		page = pfn_to_page(pfn + iter);
 
 		/*

mm/page_ext.c

···
  * can utilize this callback to initialize the state of it correctly.
  */
 
+#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
+static bool need_page_idle(void)
+{
+	return true;
+}
+struct page_ext_operations page_idle_ops = {
+	.need = need_page_idle,
+};
+#endif
+
 static struct page_ext_operations *page_ext_ops[] = {
 #ifdef CONFIG_PAGE_OWNER
 	&page_owner_ops,
 #endif
-#if defined(CONFIG_IDLE_PAGE_TRACKING) && !defined(CONFIG_64BIT)
+#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
 	&page_idle_ops,
 #endif
 };

mm/page_idle.c

···
 	.name = "page_idle",
 };
 
-#ifndef CONFIG_64BIT
-static bool need_page_idle(void)
-{
-	return true;
-}
-struct page_ext_operations page_idle_ops = {
-	.need = need_page_idle,
-};
-#endif
-
 static int __init page_idle_init(void)
 {
 	int err;

mm/page_isolation.c

···
 			buddy_pfn = __find_buddy_pfn(pfn, order);
 			buddy = page + (buddy_pfn - pfn);
 
-			if (pfn_valid_within(buddy_pfn) &&
-			    !is_migrate_isolate_page(buddy)) {
+			if (!is_migrate_isolate_page(buddy)) {
 				__isolate_free_page(page, order);
 				isolated_page = true;
 			}
···
 	struct page *page;
 
 	while (pfn < end_pfn) {
-		if (!pfn_valid_within(pfn)) {
-			pfn++;
-			continue;
-		}
 		page = pfn_to_page(pfn);
 		if (PageBuddy(page))
 			/*

mm/page_owner.c

···
 		pageblock_mt = get_pageblock_migratetype(page);
 
 		for (; pfn < block_end_pfn; pfn++) {
-			if (!pfn_valid_within(pfn))
-				continue;
-
 			/* The pageblock is online, no need to recheck. */
 			page = pfn_to_page(pfn);
 
···
 			continue;
 		}
 
-		/* Check for holes within a MAX_ORDER area */
-		if (!pfn_valid_within(pfn))
-			continue;
-
 		page = pfn_to_page(pfn);
 		if (PageBuddy(page)) {
 			unsigned long freepage_order = buddy_order_unsafe(page);
···
 		block_end_pfn = min(block_end_pfn, end_pfn);
 
 		for (; pfn < block_end_pfn; pfn++) {
-			struct page *page;
+			struct page *page = pfn_to_page(pfn);
 			struct page_ext *page_ext;
-
-			if (!pfn_valid_within(pfn))
-				continue;
-
-			page = pfn_to_page(pfn);
 
 			if (page_zone(page) != zone)
 				continue;

mm/percpu.c

···
 
 /* the address of the first chunk which starts with the kernel static area */
 void *pcpu_base_addr __ro_after_init;
-EXPORT_SYMBOL_GPL(pcpu_base_addr);
 
 static const int *pcpu_unit_map __ro_after_init;		/* cpu -> unit */
 const unsigned long *pcpu_unit_offsets __ro_after_init;	/* cpu -> unit offset */

mm/rmap.c

···
 						nr_pages);
 	} else {
 		if (PageTransCompound(page) && page_mapping(page)) {
+			struct page *head = compound_head(page);
+
 			VM_WARN_ON_ONCE(!PageLocked(page));
 
-			SetPageDoubleMap(compound_head(page));
+			SetPageDoubleMap(head);
 			if (PageMlocked(page))
-				clear_page_mlock(compound_head(page));
+				clear_page_mlock(head);
 		}
 		if (!atomic_inc_and_test(&page->_mapcount))
 			goto out;

mm/secretmem.c

···
 #include <linux/secretmem.h>
 #include <linux/set_memory.h>
 #include <linux/sched/signal.h>
+#include <linux/refcount.h>
 
 #include <uapi/linux/magic.h>
 
···
 MODULE_PARM_DESC(secretmem_enable,
 		 "Enable secretmem and memfd_secret(2) system call");
 
-static atomic_t secretmem_users;
+static refcount_t secretmem_users;
 
 bool secretmem_active(void)
 {
-	return !!atomic_read(&secretmem_users);
+	return !!refcount_read(&secretmem_users);
 }
 
 static vm_fault_t secretmem_fault(struct vm_fault *vmf)
···
 
 static int secretmem_release(struct inode *inode, struct file *file)
 {
-	atomic_dec(&secretmem_users);
+	refcount_dec(&secretmem_users);
 	return 0;
 }
 
···
 	file->f_flags |= O_LARGEFILE;
 
 	fd_install(fd, file);
-	atomic_inc(&secretmem_users);
+	refcount_inc(&secretmem_users);
 	return fd;
 
 err_put_fd:

mm/vmalloc.c

···
 #include "internal.h"
 #include "pgalloc-track.h"
 
+#ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
+static unsigned int __ro_after_init ioremap_max_page_shift = BITS_PER_LONG - 1;
+
+static int __init set_nohugeiomap(char *str)
+{
+	ioremap_max_page_shift = PAGE_SHIFT;
+	return 0;
+}
+early_param("nohugeiomap", set_nohugeiomap);
+#else /* CONFIG_HAVE_ARCH_HUGE_VMAP */
+static const unsigned int ioremap_max_page_shift = PAGE_SHIFT;
+#endif	/* CONFIG_HAVE_ARCH_HUGE_VMAP */
+
 #ifdef CONFIG_HAVE_ARCH_HUGE_VMALLOC
 static bool __ro_after_init vmap_allow_huge = true;
 
···
 	return err;
 }
 
-int vmap_range(unsigned long addr, unsigned long end,
-			phys_addr_t phys_addr, pgprot_t prot,
-			unsigned int max_page_shift)
+int ioremap_page_range(unsigned long addr, unsigned long end,
+		phys_addr_t phys_addr, pgprot_t prot)
 {
 	int err;
 
-	err = vmap_range_noflush(addr, end, phys_addr, prot, max_page_shift);
+	err = vmap_range_noflush(addr, end, phys_addr, pgprot_nx(prot),
+				 ioremap_max_page_shift);
 	flush_cache_vmap(addr, end);
-
 	return err;
 }
 

mm/workingset.c

···
  * @target_memcg: the cgroup that is causing the reclaim
  * @page: the page being evicted
  *
- * Returns a shadow entry to be stored in @page->mapping->i_pages in place
+ * Return: a shadow entry to be stored in @page->mapping->i_pages in place
  * of the evicted @page so that a later refault can be detected.
  */
 void *workingset_eviction(struct page *page, struct mem_cgroup *target_memcg)

scripts/check_extable.sh

···
 
 obj=$1
 
-file ${obj} | grep -q ELF || (echo "${obj} is not and ELF file." 1>&2 ; exit 0)
+file ${obj} | grep -q ELF || (echo "${obj} is not an ELF file." 1>&2 ; exit 0)
 
 # Bail out early if there isn't an __ex_table section in this object file.
 objdump -hj __ex_table ${obj} 2> /dev/null > /dev/null

scripts/checkpatch.pl

···
 our $Hex	= qr{(?i)0x[0-9a-f]+$Int_type?};
 our $Int	= qr{[0-9]+$Int_type?};
 our $Octal	= qr{0[0-7]+$Int_type?};
-our $String	= qr{"[X\t]*"};
+our $String	= qr{(?:\b[Lu])?"[X\t]*"};
 our $Float_hex	= qr{(?i)0x[0-9a-f]+p-?[0-9]+[fl]?};
 our $Float_dec	= qr{(?i)(?:[0-9]+\.[0-9]*|[0-9]*\.[0-9]+)(?:e-?[0-9]+)?[fl]?};
 our $Float_int	= qr{(?i)[0-9]+e-?[0-9]+[fl]?};
···
 #		    git log --format='%H %s' -1 $line |
 #		    echo "commit $(cut -c 1-12,41-)"
 #		done
-	} elsif ($lines[0] =~ /^fatal: ambiguous argument '$commit': unknown revision or path not in the working tree\./) {
+	} elsif ($lines[0] =~ /^fatal: ambiguous argument '$commit': unknown revision or path not in the working tree\./ ||
+		 $lines[0] =~ /^fatal: bad object $commit/) {
 		$id = undef;
 	} else {
 		$id = substr($lines[0], 0, 12);
···
 	my $reported_maintainer_file = 0;
 	my $non_utf8_charset = 0;
 
+	my $last_git_commit_id_linenr = -1;
+
 	my $last_blank_line = 0;
 	my $last_coalesced_string_linenr = -1;
 
···
 					my ($email_name, $email_comment, $email_address, $comment1) = parse_email($ctx);
 					my ($author_name, $author_comment, $author_address, $comment2) = parse_email($author);
 
-					if ($email_address eq $author_address && $email_name eq $author_name) {
+					if (lc $email_address eq lc $author_address && $email_name eq $author_name) {
 						$author_sob = $ctx;
 						$authorsignoff = 2;
-					} elsif ($email_address eq $author_address) {
+					} elsif (lc $email_address eq lc $author_address) {
 						$author_sob = $ctx;
 						$authorsignoff = 3;
 					} elsif ($email_name eq $author_name) {
···
 		}
 
 # Check for git id commit length and improperly formed commit descriptions
-		if ($in_commit_log && !$commit_log_possible_stack_dump &&
+# A correctly formed commit description is:
+#    commit <SHA-1 hash length 12+ chars> ("Complete commit subject")
+# with the commit subject '("' prefix and '")' suffix
+# This is a fairly compilicated block as it tests for what appears to be
+# bare SHA-1 hash with  minimum length of 5.  It also avoids several types of
+# possible SHA-1 matches.
+# A commit match can span multiple lines so this block attempts to find a
+# complete typical commit on a maximum of 3 lines
+		if ($perl_version_ok &&
+		    $in_commit_log && !$commit_log_possible_stack_dump &&
 		    $line !~ /^\s*(?:Link|Patchwork|http|https|BugLink|base-commit):/i &&
 		    $line !~ /^This reverts commit [0-9a-f]{7,40}/ &&
-		    ($line =~ /\bcommit\s+[0-9a-f]{5,}\b/i ||
+		    (($line =~ /\bcommit\s+[0-9a-f]{5,}\b/i ||
+		      ($line =~ /\bcommit\s*$/i && defined($rawlines[$linenr]) && $rawlines[$linenr] =~ /^\s*[0-9a-f]{5,}\b/i)) ||
 		     ($line =~ /(?:\s|^)[0-9a-f]{12,40}(?:[\s"'\(\[]|$)/i &&
 		      $line !~ /[\<\[][0-9a-f]{12,40}[\>\]]/i &&
 		      $line !~ /\bfixes:\s*[0-9a-f]{12,40}/i))) {
···
 			my $long = 0;
 			my $case = 1;
 			my $space = 1;
-			my $hasdesc = 0;
-			my $hasparens = 0;
 			my $id = '0123456789ab';
 			my $orig_desc = "commit description";
 			my $description = "";
+			my $herectx = $herecurr;
+			my $has_parens = 0;
+			my $has_quotes = 0;
 
-			if ($line =~ /\b(c)ommit\s+([0-9a-f]{5,})\b/i) {
-				$init_char = $1;
-				$orig_commit = lc($2);
-			} elsif ($line =~ /\b([0-9a-f]{12,40})\b/i) {
-				$orig_commit = lc($1);
+			my $input = $line;
+			if ($line =~ /(?:\bcommit\s+[0-9a-f]{5,}|\bcommit\s*$)/i) {
+				for (my $n = 0; $n < 2; $n++) {
+					if ($input =~ /\bcommit\s+[0-9a-f]{5,}\s*($balanced_parens)/i) {
+						$orig_desc = $1;
+						$has_parens = 1;
+						# Always strip leading/trailing parens then double quotes if existing
+						$orig_desc = substr($orig_desc, 1, -1);
+						if ($orig_desc =~ /^".*"$/) {
+							$orig_desc = substr($orig_desc, 1, -1);
+							$has_quotes = 1;
+						}
+						last;
+					}
+					last if ($#lines < $linenr + $n);
+					$input .= " " . trim($rawlines[$linenr + $n]);
+					$herectx .= "$rawlines[$linenr + $n]\n";
+				}
+				$herectx = $herecurr if (!$has_parens);
 			}
 
-			$short = 0 if ($line =~ /\bcommit\s+[0-9a-f]{12,40}/i);
-			$long = 1 if ($line =~ /\bcommit\s+[0-9a-f]{41,}/i);
-			$space = 0 if ($line =~ /\bcommit [0-9a-f]/i);
-			$case = 0 if ($line =~ /\b[Cc]ommit\s+[0-9a-f]{5,40}[^A-F]/);
-			if ($line =~ /\bcommit\s+[0-9a-f]{5,}\s+\("([^"]+)"\)/i) {
-				$orig_desc = $1;
-				$hasparens = 1;
-			} elsif ($line =~ /\bcommit\s+[0-9a-f]{5,}\s*$/i &&
-				 defined $rawlines[$linenr] &&
-				 $rawlines[$linenr] =~ /^\s*\("([^"]+)"\)/) {
-				$orig_desc = $1;
-				$hasparens = 1;
-			} elsif ($line =~ /\bcommit\s+[0-9a-f]{5,}\s+\("[^"]+$/i &&
-				 defined $rawlines[$linenr] &&
-				 $rawlines[$linenr] =~ /^\s*[^"]+"\)/) {
-				$line =~ /\bcommit\s+[0-9a-f]{5,}\s+\("([^"]+)$/i;
-				$orig_desc = $1;
-				$rawlines[$linenr] =~ /^\s*([^"]+)"\)/;
-				$orig_desc .= " " . $1;
-				$hasparens = 1;
+			if ($input =~ /\b(c)ommit\s+([0-9a-f]{5,})\b/i) {
+				$init_char = $1;
+				$orig_commit = lc($2);
+				$short = 0 if ($input =~ /\bcommit\s+[0-9a-f]{12,40}/i);
+				$long = 1 if ($input =~ /\bcommit\s+[0-9a-f]{41,}/i);
+				$space = 0 if ($input =~ /\bcommit [0-9a-f]/i);
+				$case = 0 if ($input =~ /\b[Cc]ommit\s+[0-9a-f]{5,40}[^A-F]/);
+			} elsif ($input =~ /\b([0-9a-f]{12,40})\b/i) {
+				$orig_commit = lc($1);
 			}
 
 			($id, $description) = git_commit_info($orig_commit,
 							      $id, $orig_desc);
 
 			if (defined($id) &&
-			   ($short || $long || $space || $case || ($orig_desc ne $description) || !$hasparens)) {
+			    ($short || $long || $space || $case || ($orig_desc ne $description) || !$has_quotes) &&
+			    $last_git_commit_id_linenr != $linenr - 1) {
 				ERROR("GIT_COMMIT_ID",
-				      "Please use git commit description style 'commit <12+ chars of sha1> (\"<title line>\")' - ie: '${init_char}ommit $id (\"$description\")'\n" . $herecurr);
+				      "Please use git commit description style 'commit <12+ chars of sha1> (\"<title line>\")' - ie: '${init_char}ommit $id (\"$description\")'\n" . $herectx);
 			}
+			#don't report the next line if this line ends in commit and the sha1 hash is the next line
+			$last_git_commit_id_linenr = $linenr if ($line =~ /\bcommit\s*$/i);
 		}
 
 # Check for added, moved or deleted files
···
 		}
 
 # concatenated string without spaces between elements
-		if ($line =~ /$String[A-Za-z0-9_]/ || $line =~ /[A-Za-z0-9_]$String/) {
+		if ($line =~ /$String[A-Z_]/ ||
+		    ($line =~ /([A-Za-z0-9_]+)$String/ && $1 !~ /^[Lu]$/)) {
 			if (CHK("CONCATENATED_STRING",
 				"Concatenated strings should use spaces between elements\n" . $herecurr) &&
 			    $fix) {
···
 		}
 
 # uncoalesced string fragments
-		if ($line =~ /$String\s*"/) {
+		if ($line =~ /$String\s*[Lu]?"/) {
 			if (WARN("STRING_FRAGMENTS",
 				 "Consecutive strings are generally better as a single string\n" . $herecurr) &&
 			    $fix) {

tools/include/linux/bitmap.h

···
 }
 
 /**
- * bitmap_alloc - Allocate bitmap
+ * bitmap_zalloc - Allocate bitmap
  * @nbits: Number of bits
  */
-static inline unsigned long *bitmap_alloc(int nbits)
+static inline unsigned long *bitmap_zalloc(int nbits)
 {
 	return calloc(1, BITS_TO_LONGS(nbits) * sizeof(unsigned long));
 }

tools/perf/bench/find-bit-bench.c

···
 
 static int do_for_each_set_bit(unsigned int num_bits)
 {
-	unsigned long *to_test = bitmap_alloc(num_bits);
+	unsigned long *to_test = bitmap_zalloc(num_bits);
 	struct timeval start, end, diff;
 	u64 runtime_us;
 	struct stats fb_time_stats, tb_time_stats;

tools/perf/builtin-c2c.c

···
 	if (!c2c_he)
 		return NULL;
 
-	c2c_he->cpuset = bitmap_alloc(c2c.cpus_cnt);
+	c2c_he->cpuset = bitmap_zalloc(c2c.cpus_cnt);
 	if (!c2c_he->cpuset)
 		return NULL;
 
-	c2c_he->nodeset = bitmap_alloc(c2c.nodes_cnt);
+	c2c_he->nodeset = bitmap_zalloc(c2c.nodes_cnt);
 	if (!c2c_he->nodeset)
 		return NULL;
 
···
 		struct perf_cpu_map *map = n[node].map;
 		unsigned long *set;
 
-		set = bitmap_alloc(c2c.cpus_cnt);
+		set = bitmap_zalloc(c2c.cpus_cnt);
 		if (!set)
 			return -ENOMEM;
 

tools/perf/builtin-record.c

···
 
 	if (rec->opts.affinity != PERF_AFFINITY_SYS) {
 		rec->affinity_mask.nbits = cpu__max_cpu();
-		rec->affinity_mask.bits = bitmap_alloc(rec->affinity_mask.nbits);
+		rec->affinity_mask.bits = bitmap_zalloc(rec->affinity_mask.nbits);
 		if (!rec->affinity_mask.bits) {
 			pr_err("Failed to allocate thread mask for %zd cpus\n", rec->affinity_mask.nbits);
 			err = -ENOMEM;

tools/perf/tests/bitmap.c

···
 	unsigned long *bm = NULL;
 	int i;
 
-	bm = bitmap_alloc(nbits);
+	bm = bitmap_zalloc(nbits);
 
 	if (map && bm) {
 		for (i = 0; i < map->nr; i++)

tools/perf/tests/mem2node.c

···
 	unsigned long *bm = NULL;
 	int i;
 
-	bm = bitmap_alloc(nbits);
+	bm = bitmap_zalloc(nbits);
 
 	if (map && bm) {
 		for (i = 0; i < map->nr; i++) {

tools/perf/util/affinity.c

···
 {
 	int cpu_set_size = get_cpu_set_size();
 
-	a->orig_cpus = bitmap_alloc(cpu_set_size * 8);
+	a->orig_cpus = bitmap_zalloc(cpu_set_size * 8);
 	if (!a->orig_cpus)
 		return -1;
 	sched_getaffinity(0, cpu_set_size, (cpu_set_t *)a->orig_cpus);
-	a->sched_cpus = bitmap_alloc(cpu_set_size * 8);
+	a->sched_cpus = bitmap_zalloc(cpu_set_size * 8);
 	if (!a->sched_cpus) {
 		zfree(&a->orig_cpus);
 		return -1;

tools/perf/util/header.c

···
 	if (ret)
 		return ret;
 
-	set = bitmap_alloc(size);
+	set = bitmap_zalloc(size);
 	if (!set)
 		return -ENOMEM;
 
···
 
 	size++;
 
-	n->set = bitmap_alloc(size);
+	n->set = bitmap_zalloc(size);
 	if (!n->set) {
 		closedir(dir);
 		return -ENOMEM;

tools/perf/util/metricgroup.c

···
 	struct evsel *evsel, *tmp;
 	unsigned long *evlist_used;
 
-	evlist_used = bitmap_alloc(perf_evlist->core.nr_entries);
+	evlist_used = bitmap_zalloc(perf_evlist->core.nr_entries);
 	if (!evlist_used)
 		return -ENOMEM;
 

tools/perf/util/mmap.c

···
 		data = map->aio.data[idx];
 		mmap_len = mmap__mmap_len(map);
 		node_index = cpu__get_node(cpu);
-		node_mask = bitmap_alloc(node_index + 1);
+		node_mask = bitmap_zalloc(node_index + 1);
 		if (!node_mask) {
 			pr_err("Failed to allocate node mask for mbind: error %m\n");
 			return -1;
···
 static int perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params *mp)
 {
 	map->affinity_mask.nbits = cpu__max_cpu();
-	map->affinity_mask.bits = bitmap_alloc(map->affinity_mask.nbits);
+	map->affinity_mask.bits = bitmap_zalloc(map->affinity_mask.nbits);
 	if (!map->affinity_mask.bits)
 		return -1;
 

tools/testing/selftests/damon/Makefile

···
+# SPDX-License-Identifier: GPL-2.0
+# Makefile for damon selftests
+
+TEST_FILES = _chk_dependency.sh
+TEST_PROGS = debugfs_attrs.sh
+
+include ../lib.mk

tools/testing/selftests/damon/_chk_dependency.sh

···
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+
+DBGFS=/sys/kernel/debug/damon
+
+if [ $EUID -ne 0 ];
+then
+	echo "Run as root"
+	exit $ksft_skip
+fi
+
+if [ ! -d "$DBGFS" ]
+then
+	echo "$DBGFS not found"
+	exit $ksft_skip
+fi
+
+for f in attrs target_ids monitor_on
+do
+	if [ ! -f "$DBGFS/$f" ]
+	then
+		echo "$f not found"
+		exit 1
+	fi
+done

tools/testing/selftests/damon/debugfs_attrs.sh

···
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+
+test_write_result() {
+	file=$1
+	content=$2
+	orig_content=$3
+	expect_reason=$4
+	expected=$5
+
+	echo "$content" > "$file"
+	if [ $? -ne "$expected" ]
+	then
+		echo "writing $content to $file doesn't return $expected"
+		echo "expected because: $expect_reason"
+		echo "$orig_content" > "$file"
+		exit 1
+	fi
+}
+
+test_write_succ() {
+	test_write_result "$1" "$2" "$3" "$4" 0
+}
+
+test_write_fail() {
+	test_write_result "$1" "$2" "$3" "$4" 1
+}
+
+test_content() {
+	file=$1
+	orig_content=$2
+	expected=$3
+	expect_reason=$4
+
+	content=$(cat "$file")
+	if [ "$content" != "$expected" ]
+	then
+		echo "reading $file expected $expected but $content"
+		echo "expected because: $expect_reason"
+		echo "$orig_content" > "$file"
+		exit 1
+	fi
+}
+
+source ./_chk_dependency.sh
+
+# Test attrs file
+# ===============
+
+file="$DBGFS/attrs"
+orig_content=$(cat "$file")
+
+test_write_succ "$file" "1 2 3 4 5" "$orig_content" "valid input"
+test_write_fail "$file" "1 2 3 4" "$orig_content" "no enough fields"
+test_write_fail "$file" "1 2 3 5 4" "$orig_content" \
+	"min_nr_regions > max_nr_regions"
+test_content "$file" "$orig_content" "1 2 3 4 5" "successfully written"
+echo "$orig_content" > "$file"
+
+# Test target_ids file
+# ====================
+
+file="$DBGFS/target_ids"
+orig_content=$(cat "$file")
+
+test_write_succ "$file" "1 2 3 4" "$orig_content" "valid input"
+test_write_succ "$file" "1 2 abc 4" "$orig_content" "still valid input"
+test_content "$file" "$orig_content" "1 2" "non-integer was there"
+test_write_succ "$file" "abc 2 3" "$orig_content" "the file allows wrong input"
+test_content "$file" "$orig_content" "" "wrong input written"
+test_write_succ "$file" "" "$orig_content" "empty input"
+test_content "$file" "$orig_content" "" "empty input written"
+echo "$orig_content" > "$file"
+
+echo "PASS"

tools/testing/selftests/kvm/dirty_log_perf_test.c

···
 	guest_num_pages = (nr_vcpus * guest_percpu_mem_size) >> vm_get_page_shift(vm);
 	guest_num_pages = vm_adjust_num_guest_pages(mode, guest_num_pages);
 	host_num_pages = vm_num_host_pages(mode, guest_num_pages);
-	bmap = bitmap_alloc(host_num_pages);
+	bmap = bitmap_zalloc(host_num_pages);
 
 	if (dirty_log_manual_caps) {
 		cap.cap = KVM_CAP_MANUAL_DIRTY_LOG_PROTECT2;

tools/testing/selftests/kvm/dirty_log_test.c

···
 
 	pr_info("guest physical test memory offset: 0x%lx\n", guest_test_phys_mem);
 
-	bmap = bitmap_alloc(host_num_pages);
-	host_bmap_track = bitmap_alloc(host_num_pages);
+	bmap = bitmap_zalloc(host_num_pages);
+	host_bmap_track = bitmap_zalloc(host_num_pages);
 
 	/* Add an extra memory slot for testing dirty logging */
 	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS,

tools/testing/selftests/kvm/x86_64/vmx_dirty_log_test.c

···
 	nested_map(vmx, vm, NESTED_TEST_MEM1, GUEST_TEST_MEM, 4096);
 	nested_map(vmx, vm, NESTED_TEST_MEM2, GUEST_TEST_MEM, 4096);
 
-	bmap = bitmap_alloc(TEST_MEM_PAGES);
+	bmap = bitmap_zalloc(TEST_MEM_PAGES);
 	host_test_mem = addr_gpa2hva(vm, GUEST_TEST_MEM);
 
 	while (!done) {

tools/testing/selftests/memfd/memfd_test.c

···
 
 static int mfd_assert_reopen_fd(int fd_in)
 {
-	int r, fd;
+	int fd;
 	char path[100];
 
 	sprintf(path, "/proc/self/fd/%d", fd_in);