tjh.dev
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
code
Clone this repository
https://tangled.org/tjh.dev/kernel
git@gordian.tjh.dev:tjh.dev/kernel
For self-hosted knots, clone URLs may differ based on your setup.
Pull perf tools fixes from Arnaldo Carvalho de Melo:
- Skip invalid hybrid PMU on hybrid systems when the atom (little) CPUs
are offlined.
- Fix 'perf test' problems related to the recently added hybrid
(BIG/little) code.
- Split ARM's coresight (hw tracing) decode by aux records to avoid
fatal decoding errors.
- Fix add event failure in 'perf probe' when running 32-bit perf in a
64-bit kernel.
- Fix 'perf sched record' failure when CONFIG_SCHEDSTATS is not set.
- Fix memory and refcount leaks detected by ASAn when running 'perf
test', should be clean of warnings now.
- Remove broken definition of __LITTLE_ENDIAN from tools'
linux/kconfig.h, which was breaking the build in some systems.
- Cast PTHREAD_STACK_MIN to int as it may turn into 'long
sysconf(__SC_THREAD_STACK_MIN_VALUE), breaking the build in some
systems.
- Fix libperf build error with LIBPFM4=1.
- Sync UAPI files changed by the memfd_secret new syscall.
* tag 'perf-tools-fixes-for-v5.14-2021-07-18' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux: (35 commits)
perf sched: Fix record failure when CONFIG_SCHEDSTATS is not set
perf probe: Fix add event failure when running 32-bit perf in a 64-bit kernel
perf data: Close all files in close_dir()
perf probe-file: Delete namelist in del_events() on the error path
perf test bpf: Free obj_buf
perf trace: Free strings in trace__parse_events_option()
perf trace: Free syscall tp fields in evsel->priv
perf trace: Free syscall->arg_fmt
perf trace: Free malloc'd trace fields on exit
perf lzma: Close lzma stream on exit
perf script: Fix memory 'threads' and 'cpus' leaks on exit
perf script: Release zstd data
perf session: Cleanup trace_event
perf inject: Close inject.output on exit
perf report: Free generated help strings for sort option
perf env: Fix memory leak of cpu_pmu_caps
perf test maps__merge_in: Fix memory leak of maps
perf dso: Fix memory leak in dso__new_map()
perf test event_update: Fix memory leak of unit
perf test event_update: Fix memory leak of evlist
...
Pull xfs fixes from Darrick Wong:
"A few fixes for issues in the new online shrink code, additional
corrections for my recent bug-hunt w.r.t. extent size hints on
realtime, and improved input checking of the GROWFSRT ioctl.
IOW, the usual 'I somehow got bored during the merge window and
resumed auditing the farther reaches of xfs':
- Fix shrink eligibility checking when sparse inode clusters enabled
- Reset '..' directory entries when unlinking directories to prevent
verifier errors if fs is shrinked later
- Don't report unusable extent size hints to FSGETXATTR
- Don't warn when extent size hints are unusable because the sysadmin
configured them that way
- Fix insufficient parameter validation in GROWFSRT ioctl
- Fix integer overflow when adding rt volumes to filesystem"
* tag 'xfs-5.14-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
xfs: detect misaligned rtinherit directory extent size hints
xfs: fix an integer overflow error in xfs_growfs_rt
xfs: improve FSGROWFSRT precondition checking
xfs: don't expose misaligned extszinherit hints to userspace
xfs: correct the narrative around misaligned rtinherit/extszinherit dirs
xfs: reset child dir '..' entry when unlinking child
xfs: check for sparse inode clusters that cross new EOAG when shrinking
The tracepoints trace_sched_stat_{wait, sleep, iowait} are not exposed to user
if CONFIG_SCHEDSTATS is not set, "perf sched record" records the three events.
As a result, the command fails.
Before:
#perf sched record sleep 1
event syntax error: 'sched:sched_stat_wait'
\___ unknown tracepoint
Error: File /sys/kernel/tracing/events/sched/sched_stat_wait not found.
Hint: Perhaps this kernel misses some CONFIG_ setting to enable this feature?.
Run 'perf list' for a list of valid events
Usage: perf record [<options>] [<command>]
or: perf record [<options>] -- <command> [<options>]
-e, --event <event> event selector. use 'perf list' to list available events
Solution:
Check whether schedstat tracepoints are exposed. If no, these events are not recorded.
After:
# perf sched record sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.163 MB perf.data (1091 samples) ]
# perf sched report
run measurement overhead: 4736 nsecs
sleep measurement overhead: 9059979 nsecs
the run test took 999854 nsecs
the sleep test took 8945271 nsecs
nr_run_events: 716
nr_sleep_events: 785
nr_wakeup_events: 0
...
------------------------------------------------------------
Fixes: 2a09b5de235a6 ("sched/fair: do not expose some tracepoints to user if CONFIG_SCHEDSTATS is not set")
Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Yafang Shao <laoar.shao@gmail.com>
Link: http://lore.kernel.org/lkml/20210713112358.194693-1-yangjihong1@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Pull iomap fixes from Darrick Wong:
"A handful of bugfixes for the iomap code.
There's nothing especially exciting here, just fixes for UBSAN (not
KASAN as I erroneously wrote in the tag message) warnings about
undefined behavior in the SEEK_DATA/SEEK_HOLE code, and some
reshuffling of per-page block state info to fix some problems with
gfs2.
- Fix KASAN warnings due to integer overflow in SEEK_DATA/SEEK_HOLE
- Fix assertion errors when using inlinedata files on gfs2"
* tag 'iomap-5.14-fixes-1' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux:
iomap: Don't create iomap_page objects in iomap_page_mkwrite_actor
iomap: Don't create iomap_page objects for inline files
iomap: Permit pages without an iop to enter writeback
iomap: remove the length variable in iomap_seek_hole
iomap: remove the length variable in iomap_seek_data
If we encounter a directory that has been configured to pass on an
extent size hint to a new realtime file and the hint isn't an integer
multiple of the rt extent size, we should flag the hint for
administrative review because that is a misconfiguration (that other
parts of the kernel will fix automatically).
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
The "address" member of "struct probe_trace_point" uses long data type.
If kernel is 64-bit and perf program is 32-bit, size of "address"
variable is 32 bits.
As a result, upper 32 bits of address read from kernel are truncated, an
error occurs during address comparison in kprobe_warn_out_range().
Before:
# perf probe -a schedule
schedule is out of .text, skip it.
Error: Failed to add events.
Solution:
Change data type of "address" variable to u64 and change corresponding
address printing and value assignment.
After:
# perf.new.new probe -a schedule
Added new event:
probe:schedule (on schedule)
You can now use it in all perf tools, such as:
perf record -e probe:schedule -aR sleep 1
# perf probe -l
probe:schedule (on schedule@kernel/sched/core.c)
# perf record -e probe:schedule -aR sleep 1
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.156 MB perf.data (1366 samples) ]
# perf report --stdio
# To display the perf.data header info, please use --header/--header-only options.
#
#
# Total Lost Samples: 0
#
# Samples: 1K of event 'probe:schedule'
# Event count (approx.): 1366
#
# Overhead Command Shared Object Symbol
# ........ ............... ................. ............
#
6.22% migration/0 [kernel.kallsyms] [k] schedule
6.22% migration/1 [kernel.kallsyms] [k] schedule
6.22% migration/2 [kernel.kallsyms] [k] schedule
6.22% migration/3 [kernel.kallsyms] [k] schedule
6.15% migration/10 [kernel.kallsyms] [k] schedule
6.15% migration/11 [kernel.kallsyms] [k] schedule
6.15% migration/12 [kernel.kallsyms] [k] schedule
6.15% migration/13 [kernel.kallsyms] [k] schedule
6.15% migration/14 [kernel.kallsyms] [k] schedule
6.15% migration/15 [kernel.kallsyms] [k] schedule
6.15% migration/4 [kernel.kallsyms] [k] schedule
6.15% migration/5 [kernel.kallsyms] [k] schedule
6.15% migration/6 [kernel.kallsyms] [k] schedule
6.15% migration/7 [kernel.kallsyms] [k] schedule
6.15% migration/8 [kernel.kallsyms] [k] schedule
6.15% migration/9 [kernel.kallsyms] [k] schedule
0.22% rcu_sched [kernel.kallsyms] [k] schedule
...
#
# (Cannot load tips.txt file, please install perf!)
#
Signed-off-by: Yang Jihong <yangjihong1@huawei.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jianlin Lv <jianlin.lv@arm.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Li Huafei <lihuafei1@huawei.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ravi Bangoria <ravi.bangoria@linux.ibm.com>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Link: http://lore.kernel.org/lkml/20210715063723.11926-1-yangjihong1@huawei.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Pull Kbuild fixes from Masahiro Yamada:
- Restore the original behavior of scripts/setlocalversion when
LOCALVERSION is set to empty.
- Show Kconfig prompts even for 'make -s'
- Fix the combination of COFNIG_LTO_CLANG=y and CONFIG_MODVERSIONS=y
for older GNU Make versions
* tag 'kbuild-fixes-v5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/masahiroy/linux-kbuild:
Documentation: Fix intiramfs script name
Kbuild: lto: fix module versionings mismatch in GNU make 3.X
kbuild: do not suppress Kconfig prompts for silent build
scripts/setlocalversion: fix a bug when LOCALVERSION is empty
Now that we create those objects in iomap_writepage_map when needed,
there's no need to pre-create them in iomap_page_mkwrite_actor anymore.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
During a realtime grow operation, we run a single transaction for each
rt bitmap block added to the filesystem. This means that each step has
to be careful to increase sb_rblocks appropriately.
Fix the integer overflow error in this calculation that can happen when
the extent size is very large. Found by running growfs to add a rt
volume to a filesystem formatted with a 1g rt extent size.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
When using 'perf report' in directory mode, the first file is not closed
on exit, causing a memory leak.
The problem is caused by the iterating variable never reaching 0.
Fixes: 145520631130bd64 ("perf data: Add perf_data__(create_dir|close_dir) functions")
Signed-off-by: Riccardo Mancini <rickyman7@gmail.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Zhen Lei <thunder.leizhen@huawei.com>
Link: http://lore.kernel.org/lkml/20210716141122.858082-1-rickyman7@gmail.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Pull ARM SoC fixes from Arnd Bergmann:
"Here are the patches for this week that came as the fallout of the
merge window:
- Two fixes for the NVidia memory controller driver
- multiple defconfig files get patched to turn CONFIG_FB back on
after that is no longer selected by CONFIG_DRM
- ffa and scmpi firmware drivers fixes, mostly addressing compiler
and documentation warnings
- Platform specific fixes for device tree files on ASpeed, Renesas
and NVidia SoC, mostly for recent regressions.
- A workaround for a regression on the USB PHY with devlink when the
usb-nop-xceiv driver is not available until the rootfs is mounted.
- Device tree compiler warnings in Arm Versatile-AB"
* tag 'soc-fixes-5.14-1' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (35 commits)
ARM: dts: versatile: Fix up interrupt controller node names
ARM: multi_v7_defconfig: Make NOP_USB_XCEIV driver built-in
ARM: configs: Update u8500_defconfig
ARM: configs: Update Vexpress defconfig
ARM: configs: Update Versatile defconfig
ARM: configs: Update RealView defconfig
ARM: configs: Update Integrator defconfig
arm: Typo s/PCI_IXP4XX_LEGACY/IXP4XX_PCI_LEGACY/
firmware: arm_scmi: Fix range check for the maximum number of pending messages
firmware: arm_scmi: Avoid padding in sensor message structure
firmware: arm_scmi: Fix kernel doc warnings about return values
firmware: arm_scpi: Fix kernel doc warnings
firmware: arm_scmi: Fix kernel doc warnings
ARM: shmobile: defconfig: Restore graphical consoles
firmware: arm_ffa: Fix a possible ffa_linux_errmap buffer overflow
firmware: arm_ffa: Fix the comment style
firmware: arm_ffa: Simplify probe function
firmware: arm_ffa: Ensure drivers provide a probe function
firmware: arm_scmi: Fix possible scmi_linux_errmap buffer overflow
firmware: arm_scmi: Ensure drivers provide a probe function
...
Documentation was not changed when renaming the script in commit
80e715a06c2d ("initramfs: rename gen_initramfs_list.sh to
gen_initramfs.sh"). Fixing this.
Basically does:
$ sed -i -e s/gen_initramfs_list.sh/gen_initramfs.sh/g $(git grep -l gen_initramfs_list.sh)
Fixes: 80e715a06c2d ("initramfs: rename gen_initramfs_list.sh to gen_initramfs.sh")
Signed-off-by: Robert Richter <rrichter@amd.com>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
In iomap_readpage_actor, don't create iop objects for inline inodes.
Otherwise, iomap_read_inline_data will set PageUptodate without setting
iop->uptodate, and iomap_page_release will eventually complain.
To prevent this kind of bug from occurring in the future, make sure the
page doesn't have private data attached in iomap_read_inline_data.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
README