Linux kernel ============ The Linux kernel is the core of any Linux operating system. It manages hardware, system resources, and provides the fundamental services for all other software. Quick Start ----------- * Report a bug: See Documentation/admin-guide/reporting-issues.rst * Get the latest kernel: https://kernel.org * Build the kernel: See Documentation/admin-guide/quickly-build-trimmed-linux.rst * Join the community: https://lore.kernel.org/ Essential Documentation ----------------------- All users should be familiar with: * Building requirements: Documentation/process/changes.rst * Code of Conduct: Documentation/process/code-of-conduct.rst * License: See COPYING Documentation can be built with make htmldocs or viewed online at: https://www.kernel.org/doc/html/latest/ Who Are You? ============ Find your role below: * New Kernel Developer - Getting started with kernel development * Academic Researcher - Studying kernel internals and architecture * Security Expert - Hardening and vulnerability analysis * Backport/Maintenance Engineer - Maintaining stable kernels * System Administrator - Configuring and troubleshooting * Maintainer - Leading subsystems and reviewing patches * Hardware Vendor - Writing drivers for new hardware * Distribution Maintainer - Packaging kernels for distros For Specific Users ================== New Kernel Developer -------------------- Welcome! Start your kernel development journey here: * Getting Started: Documentation/process/development-process.rst * Your First Patch: Documentation/process/submitting-patches.rst * Coding Style: Documentation/process/coding-style.rst * Build System: Documentation/kbuild/index.rst * Development Tools: Documentation/dev-tools/index.rst * Kernel Hacking Guide: Documentation/kernel-hacking/hacking.rst * Core APIs: Documentation/core-api/index.rst Academic Researcher ------------------- Explore the kernel's architecture and internals: * Researcher Guidelines: Documentation/process/researcher-guidelines.rst * Memory Management: Documentation/mm/index.rst * Scheduler: Documentation/scheduler/index.rst * Networking Stack: Documentation/networking/index.rst * Filesystems: Documentation/filesystems/index.rst * RCU (Read-Copy Update): Documentation/RCU/index.rst * Locking Primitives: Documentation/locking/index.rst * Power Management: Documentation/power/index.rst Security Expert --------------- Security documentation and hardening guides: * Security Documentation: Documentation/security/index.rst * LSM Development: Documentation/security/lsm-development.rst * Self Protection: Documentation/security/self-protection.rst * Reporting Vulnerabilities: Documentation/process/security-bugs.rst * CVE Procedures: Documentation/process/cve.rst * Embargoed Hardware Issues: Documentation/process/embargoed-hardware-issues.rst * Security Features: Documentation/userspace-api/seccomp_filter.rst Backport/Maintenance Engineer ----------------------------- Maintain and stabilize kernel versions: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * Backporting Guide: Documentation/process/backporting.rst * Applying Patches: Documentation/process/applying-patches.rst * Subsystem Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git for Maintainers: Documentation/maintainer/configure-git.rst System Administrator -------------------- Configure, tune, and troubleshoot Linux systems: * Admin Guide: Documentation/admin-guide/index.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Sysctl Tuning: Documentation/admin-guide/sysctl/index.rst * Tracing/Debugging: Documentation/trace/index.rst * Performance Security: Documentation/admin-guide/perf-security.rst * Hardware Monitoring: Documentation/hwmon/index.rst Maintainer ---------- Lead kernel subsystems and manage contributions: * Maintainer Handbook: Documentation/maintainer/index.rst * Pull Requests: Documentation/maintainer/pull-requests.rst * Managing Patches: Documentation/maintainer/modifying-patches.rst * Rebasing and Merging: Documentation/maintainer/rebasing-and-merging.rst * Development Process: Documentation/process/maintainer-handbooks.rst * Maintainer Entry Profile: Documentation/maintainer/maintainer-entry-profile.rst * Git Configuration: Documentation/maintainer/configure-git.rst Hardware Vendor --------------- Write drivers and support new hardware: * Driver API Guide: Documentation/driver-api/index.rst * Driver Model: Documentation/driver-api/driver-model/driver.rst * Device Drivers: Documentation/driver-api/infrastructure.rst * Bus Types: Documentation/driver-api/driver-model/bus.rst * Device Tree Bindings: Documentation/devicetree/bindings/ * Power Management: Documentation/driver-api/pm/index.rst * DMA API: Documentation/core-api/dma-api.rst Distribution Maintainer ----------------------- Package and distribute the kernel: * Stable Kernel Rules: Documentation/process/stable-kernel-rules.rst * ABI Documentation: Documentation/ABI/README * Kernel Configuration: Documentation/kbuild/kconfig.rst * Module Signing: Documentation/admin-guide/module-signing.rst * Kernel Parameters: Documentation/admin-guide/kernel-parameters.rst * Tainted Kernels: Documentation/admin-guide/tainted-kernels.rst Communication and Support ========================= * Mailing Lists: https://lore.kernel.org/ * IRC: #kernelnewbies on irc.oftc.net * Bugzilla: https://bugzilla.kernel.org/ * MAINTAINERS file: Lists subsystem maintainers and mailing lists * Email Clients: Documentation/process/email-clients.rst
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Pull arm64 fixes from Catalin Marinas:
- Do not return false if !preemptible() in current_in_efi(). EFI
runtime services can now run with preemption enabled
- Fix uninitialised variable in the arm MPAM driver, reported by sparse
- Fix partial kasan_reset_tag() use in change_memory_common() when
calculating page indices or comparing ranges
- Save/restore TCR2_EL1 during suspend/resume, otherwise the E0POE bit
is lost
* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
arm64: Fix cleared E0POE bit after cpu_suspend()/resume()
arm64: mm: Fix incomplete tag reset in change_memory_common()
arm_mpam: Stop using uninitialized variables in __ris_msmon_read()
arm64/efi: Don't fail check current_in_efi() if preemptible
Pull SoC fixes from Arnd Bergmann:
"The main code change is a revert of the Raspberry Pi RP1 overlay
support that was decided to not be ready.
The other fixes are all for devicetree sources:
- ethernet configuration on ixp42x-actiontec-mi424wr is board
revision specific
- validation warning fixes for imx27/imx51/imx6, hikey960 and k3
- Minor corrections across imx8 boards, addressing all types of
issues with interrups, dma, ethernet and clock settings, all simple
one-line changes"
* tag 'soc-fixes-6.19' of git://git.kernel.org/pub/scm/linux/kernel/git/soc/soc: (25 commits)
arm64: dts: hisilicon: hikey960: Drop "snps,gctl-reset-quirk" and "snps,tx_de_emphasis*" properties
Documentation/process: maintainer-soc: Mark 'make' as commands
Documentation/process: maintainer-soc: Be more explicit about defconfig
arm64: dts: mba8mx: Fix Ethernet PHY IRQ support
arm64: dts: imx8qm-ss-dma: correct the dma channels of lpuart
arm64: dts: imx8mp: Fix LAN8740Ai PHY reference clock on DH electronics i.MX8M Plus DHCOM
arm64: dts: freescale: tx8p-ml81: fix eqos nvmem-cells
arm64: dts: freescale: moduline-display: fix compatible
dt-bindings: arm: fsl: moduline-display: fix compatible
ARM: dts: imx6q-ba16: fix RTC interrupt level
arm64: dts: freescale: imx95-toradex-smarc: fix SMARC_SDIO_WP label position
arm64: dts: freescale: imx95-toradex-smarc: use edge trigger for ethphy1 interrupt
arm64: dts: add off-on-delay-us for usdhc2 regulator
arm64: dts: imx8qm-mek: correct the light sensor interrupt type to low level
ARM: dts: nxp: imx: Fix mc13xxx LED node names
arm64: dts: imx95: correct I3C2 pclk to IMX95_CLK_BUSWAKEUP
MAINTAINERS: Fix a linusw mail address
arm64: dts: broadcom: rp1: drop RP1 overlay
arm64: dts: broadcom: bcm2712: fix RP1 endpoint PCI topology
misc: rp1: drop overlay support
...
TCR2_ELx.E0POE is set during smp_init().
However, this bit is not reprogrammed when the CPU enters suspension and
later resumes via cpu_resume(), as __cpu_setup() does not re-enable E0POE
and there is no save/restore logic for the TCR2_ELx system register.
As a result, the E0POE feature no longer works after cpu_resume().
To address this, save and restore TCR2_EL1 in the cpu_suspend()/cpu_resume()
path, rather than adding related logic to __cpu_setup(), taking into account
possible future extensions of the TCR2_ELx feature.
Fixes: bf83dae90fbc ("arm64: enable the Permission Overlay Extension for EL0")
Cc: <stable@vger.kernel.org> # 6.12.x
Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Reviewed-by: Kevin Brodsky <kevin.brodsky@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Pull ceph fixes from Ilya Dryomov:
"A bunch of libceph fixes split evenly between memory safety and
implementation correctness issues (all marked for stable) and a change
in maintainers for CephFS: Slava and Alex have formally taken over
Xiubo's role"
* tag 'ceph-for-6.19-rc5' of https://github.com/ceph/ceph-client:
libceph: make calc_target() set t->paused, not just clear it
libceph: reset sparse-read state in osd_fault()
libceph: return the handler error from mon_handle_auth_done()
libceph: make free_choose_arg_map() resilient to partial allocation
ceph: update co-maintainers list in MAINTAINERS
libceph: replace overzealous BUG_ON in osdmap_apply_incremental()
libceph: prevent potential out-of-bounds reads in handle_auth_done()
"snps,tx_de_emphasis" is supposed to be a u8, not a u32. Since it is big
endian, 0 will be read rather than 1. The DWC3 Linux driver simply ORs
the value if "snps,tx_de_emphasis_quirk" is set, so the 2 properties
have no effect. (The driver doesn't clear the field either which is
another problem).
"snps,gctl-reset-quirk" is not documented nor used in the driver, so
drop it as well.
Signed-off-by: Rob Herring (Arm) <robh@kernel.org>
Link: https://lore.kernel.org/r/20260105174002.2997615-1-robh@kernel.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Running KASAN KUnit tests with {HW,SW}_TAGS mode triggers a fault in
change_memory_common():
Call trace:
change_memory_common+0x168/0x210 (P)
set_memory_ro+0x20/0x48
vmalloc_helpers_tags+0xe8/0x338
kunit_try_run_case+0x74/0x188
kunit_generic_run_threadfn_adapter+0x30/0x70
kthread+0x11c/0x200
ret_from_fork+0x10/0x20
---[ end trace 0000000000000000 ]---
# vmalloc_helpers_tags: try faulted
not ok 67 vmalloc_helpers_tags
Commit a06494adb7ef ("arm64: mm: use untagged address to calculate page index")
fixed a KASAN warning in the BPF subsystem by adding kasan_reset_tag() to
the index calculation. In the execmem flow:
bpf_prog_pack_alloc()
-> bpf_jit_alloc_exec()
-> execmem_alloc()
The returned address from execmem_vmalloc/execmem_cache_alloc is passed
through kasan_reset_tag(), so start has no tag while area->addr still
retains the original tag. The fix correctly handled this case by resetting
the tag on area->addr:
(start - (unsigned long)kasan_reset_tag(area->addr)) >> PAGE_SHIFT
However, in normal vmalloc paths, both start and area->addr have matching
tags(or no tags). Resetting only area->addr causes a mismatch when
subtracting a tagged address from an untagged one, resulting in an
incorrect index.
Fix this by resetting tags on both addresses in the index calculation.
This ensures correct results regardless of the tag state of either address.
Tested with KASAN KUnit tests under CONFIG_KASAN_GENERIC,
CONFIG_KASAN_SW_TAGS, and CONFIG_KASAN_HW_TAGS - all pass. Also verified
the original BPF KASAN warning from [1] is still fixed.
[1] https://lore.kernel.org/all/20251118164115.GA3977565@ax162/
Fixes: a06494adb7ef ("arm64: mm: use untagged address to calculate page index")
Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com>
Signed-off-by: Jiayuan Chen <jiayuan.chen@linux.dev>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Pull btrfs fixes from David Sterba:
- fix potential NULL pointer dereference when replaying tree log after
an error
- release path before initializing extent tree to avoid potential
deadlock when allocating new inode
- on filesystems with block size > page size
- fix potential read out of bounds during encoded read of an inline
extent
- only enforce free space tree if v1 cache is required
- print correct tree id in error message
* tag 'for-6.19-rc4-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave/linux:
btrfs: show correct warning if can't read data reloc tree
btrfs: fix NULL pointer dereference in do_abort_log_replay()
btrfs: force free space tree for bs > ps cases
btrfs: only enforce free space tree if v1 cache is required for bs < ps cases
btrfs: release path before initializing extent tree in btrfs_read_locked_inode()
btrfs: avoid access-beyond-folio for bs > ps encoded writes
Currently calc_target() clears t->paused if the request shouldn't be
paused anymore, but doesn't ever set t->paused even though it's able to
determine when the request should be paused. Setting t->paused is left
to __submit_request() which is fine for regular requests but doesn't
work for linger requests -- since __submit_request() doesn't operate
on linger requests, there is nowhere for lreq->t.paused to be set.
One consequence of this is that watches don't get reestablished on
paused -> unpaused transitions in cases where requests have been paused
long enough for the (paused) unwatch request to time out and for the
subsequent (re)watch request to enter the paused state. On top of the
watch not getting reestablished, rbd_reregister_watch() gets stuck with
rbd_dev->watch_mutex held:
rbd_register_watch
__rbd_register_watch
ceph_osdc_watch
linger_reg_commit_wait
It's waiting for lreq->reg_commit_wait to be completed, but for that to
happen the respective request needs to end up on need_resend_linger list
and be kicked when requests are unpaused. There is no chance for that
if the request in question is never marked paused in the first place.
The fact that rbd_dev->watch_mutex remains taken out forever then
prevents the image from getting unmapped -- "rbd unmap" would inevitably
hang in D state on an attempt to grab the mutex.
Cc: stable@vger.kernel.org
Reported-by: Raphael Zimmer <raphael.zimmer@tu-ilmenau.de>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Viacheslav Dubeyko <Slava.Dubeyko@ibm.com>
i.MX fixes for 6.19:
- A mba8mx fix from Alexander Stein to correct Ethernet PHY IRQ trigger
type
- An i.MX95 fix from Carlos Song to correct I3C2 pclk
- A couple of imx8qm-mek changes from Haibo Chen to fix light sensor
interrupt type and usdhc2 regulator configuration
- An imx6q-ba16 change from Ian Ray to fix RTC interrupt level
- An imx8mp-dhcom-som change from Marek Vasut to fix sporadic Ethernet
link bouncing caused by interruptions on the PHY reference clock
- A couple of imx8mp-tx8p changes from Maud Spierings to fix compatible
and eqos nvmem-cells
- An ARM i.MX fix from Rob Herring to correct mc13xxx LED node names
- An imx8qm-ss-dma change from Sherry Sun to correct DMA channels for
LPUART
- A couple of imx95-toradex-smarc changes from Vitor Soares to fix
ethphy1 interrupt and SMARC_SDIO_WP label position
* tag 'imx-fixes-6.19' of https://git.kernel.org/pub/scm/linux/kernel/git/shawnguo/linux:
arm64: dts: mba8mx: Fix Ethernet PHY IRQ support
arm64: dts: imx8qm-ss-dma: correct the dma channels of lpuart
arm64: dts: imx8mp: Fix LAN8740Ai PHY reference clock on DH electronics i.MX8M Plus DHCOM
arm64: dts: freescale: tx8p-ml81: fix eqos nvmem-cells
arm64: dts: freescale: moduline-display: fix compatible
dt-bindings: arm: fsl: moduline-display: fix compatible
ARM: dts: imx6q-ba16: fix RTC interrupt level
arm64: dts: freescale: imx95-toradex-smarc: fix SMARC_SDIO_WP label position
arm64: dts: freescale: imx95-toradex-smarc: use edge trigger for ethphy1 interrupt
arm64: dts: add off-on-delay-us for usdhc2 regulator
arm64: dts: imx8qm-mek: correct the light sensor interrupt type to low level
ARM: dts: nxp: imx: Fix mc13xxx LED node names
arm64: dts: imx95: correct I3C2 pclk to IMX95_CLK_BUSWAKEUP
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Dan has reported two uses of uninitialized variables in __ris_msmon_read().
If an unknown monitor type is encountered then the local variable, now, is
used uninitialized. Fix this by returning early on error. If a non-mbwu
monitor is being read then the local variable, overflow, is not initialized
but still read. Initialize it to false as overflow is not relevant for csu
monitors.
Fixes: 823e7c3712c5 ("arm_mpam: Add mpam_msmon_read() to read monitor value")
Fixes: 9e5afb7c3283 ("arm_mpam: Use long MBWU counters if supported")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202512091519.RBwiJcSq-lkp@intel.com/
Closes: https://lore.kernel.org/r/202512100547.N7QPYgfb-lkp@intel.com/
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Pull PCI fixes from Bjorn Helgaas:
- Remove ASPM L0s support for MSM8996 SoC since we now enable L0s when
advertised, and it caused random hangs on this device (Manivannan
Sadhasivam)
- Fix meson-pcie to report that the link is up while in ASPM L0s or L1,
since those are active states from the software point of view, and
treating the link as down caused config access failures (Bjorn
Helgaas)
- Fix up sparc DTS BAR descriptions that are above 4GB but not marked
as prefetchable, which caused resource assignment and driver probe
failures after we converted from the SPARC pcibios_enable_device() to
the generic version (Ilpo Järvinen)
* tag 'pci-v6.19-fixes-2' of git://git.kernel.org/pub/scm/linux/kernel/git/pci/pci:
sparc/PCI: Correct 64-bit non-pref -> pref BAR resources
PCI: meson: Report that link is up while in ASPM L0s and L1 states
PCI: qcom: Remove ASPM L0s support for MSM8996 SoC
If a filesystem is missing its data reloc tree, we get something like
this in dmesg:
BTRFS warning (device loop11): failed to read root (objectid=4): -2
BTRFS error (device loop11): open_ctree failed: -2
objectid is BTRFS_DEV_TREE_OBJECTID, but this should actually be the
value of BTRFS_DATA_RELOC_TREE_OBJECTID.
btrfs_read_roots() prints location.objectid on failure, but this isn't
set when reading the data reloc tree. Set location.objectid to the
correct value on failure, so that the error message makes sense.
Reviewed-by: Qu Wenruo <wqu@suse.com>
Signed-off-by: Mark Harmstone <mark@harmstone.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
When a fault occurs, the connection is abandoned, reestablished, and any
pending operations are retried. The OSD client tracks the progress of a
sparse-read reply using a separate state machine, largely independent of
the messenger's state.
If a connection is lost mid-payload or the sparse-read state machine
returns an error, the sparse-read state is not reset. The OSD client
will then interpret the beginning of a new reply as the continuation of
the old one. If this makes the sparse-read machinery enter a failure
state, it may never recover, producing loops like:
libceph: [0] got 0 extents
libceph: data len 142248331 != extent len 0
libceph: osd0 (1)...:6801 socket error on read
libceph: data len 142248331 != extent len 0
libceph: osd0 (1)...:6801 socket error on read
Therefore, reset the sparse-read state in osd_fault(), ensuring retries
start from a clean state.
Cc: stable@vger.kernel.org
Fixes: f628d7999727 ("libceph: add sparse read support to OSD client")
Signed-off-by: Sam Edwards <CFSworks@gmail.com>
Reviewed-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Improve readability of the docs by marking 'make dtbs/dtbs_check' as
shell commands.
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@oss.qualcomm.com>
Reviewed-by: Linus Walleij <linusw@kernel.org>
Link: https://lore.kernel.org/r/20251223142726.73417-4-krzysztof.kozlowski@oss.qualcomm.com
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Ethernet PHY interrupt mode is level triggered. Adjust the mode
accordingly.
Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Fixes: 70cf622bb16e ("arm64: dts: mba8mx: Add Ethernet PHY IRQ support")
Signed-off-by: Shawn Guo <shawnguo@kernel.org>
As EFI runtime services can now be run without disabling preemption remove
the check for non preemptible in current_in_efi(). Without this change,
firmware errors that were previously recovered from by
__efi_runtime_kernel_fixup_exception() will lead to a kernel oops.
Fixes: a5baf582f4c0 ("arm64/efi: Call EFI runtime services without disabling preemption")
Signed-off-by: Ben Horgan <ben.horgan@arm.com>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Richard Lyu <richard.lyu@suse.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Pull ACPI support fix from Rafael Wysocki:
"This fixes the ACPI/PCI legacy interrupts (INTx) parsing in the case
when the ACPI Global System Interrupt (GSI) value is a 32-bit one with
the MSB set.
That was interpreted as a negative integer and caused
acpi_pci_link_allocate_irq() to fail and acpi_irq_get_penalty() to
trigger an out-of-bounds array dereference (Lorenzo Pieralisi)"
* tag 'acpi-6.19-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
ACPI: PCI: IRQ: Fix INTx GSIs signedness