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 rdma fixes from Jason Gunthorpe:
- Fix several syzkaller found bugs:
- Poor parsing of the RDMA_NL_LS_OP_IP_RESOLVE netlink
- GID entry refcount leaking when CM destruction races with
multicast establishment
- Missing refcount put in ib_del_sub_device_and_put()
- Fixup recently introduced uABI padding for 32 bit consistency
- Avoid user triggered math overflow in MANA and AFA
- Reading invalid netdev data during an event
- kdoc fixes
- Fix never-working gid copying in ib_get_gids_from_rdma_hdr
- Typo in bnxt when validating the BAR
- bnxt mis-parsed IB_SEND_IP_CSUM so it didn't work always
- bnxt out of bounds access in bnxt related to the counters on new
devices
- Allocate the bnxt PDE table with the right sizing
- Use dma_free_coherent() correctly in bnxt
- Allow rxe to be unloadable when CONFIG_PROVE_LOCKING by adjusting the
tracking of the global sockets it uses
- Missing unlocking on error path in rxe
- Compute the right number of pages in a MR in rtrs
* tag 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rdma/rdma:
RDMA/bnxt_re: fix dma_free_coherent() pointer
RDMA/rtrs: Fix clt_path::max_pages_per_mr calculation
IB/rxe: Fix missing umem_odp->umem_mutex unlock on error path
RDMA/bnxt_re: Fix to use correct page size for PDE table
RDMA/bnxt_re: Fix OOB write in bnxt_re_copy_err_stats()
RDMA/bnxt_re: Fix IB_SEND_IP_CSUM handling in post_send
RDMA/core: always drop device refcount in ib_del_sub_device_and_put()
RDMA/rxe: let rxe_reclassify_recv_socket() call sk_owner_put()
RDMA/bnxt_re: Fix incorrect BAR check in bnxt_qplib_map_creq_db()
RDMA/core: Fix logic error in ib_get_gids_from_rdma_hdr()
RDMA/efa: Remove possible negative shift
RTRS/rtrs: clean up rtrs headers kernel-doc
RDMA/irdma: avoid invalid read in irdma_net_event
RDMA/mana_ib: check cqe length for kernel CQs
RDMA/irdma: Fix irdma_alloc_ucontext_resp padding
RDMA/ucma: Fix rdma_ucm_query_ib_service_resp struct padding
RDMA/cm: Fix leaking the multicast GID table reference
RDMA/core: Check for the presence of LS_NLA_TYPE_DGID correctly
Pull kselftest fixes from Shuah Khan:
- Fix for build failures in tests that use an empty FIXTURE() seen in
Android's build environment, which uses -D_FORTIFY_SOURCE=3, a build
failure occurs in tests that use an empty FIXTURE()
- Fix func_traceonoff_triggers.tc sometimes failures on Kunpeng-920
board resulting from including transient trace file name in checksum
compare
- Fix to remove available_events requirement from toplevel-enable for
instance as it isn't a valid requirement for this test
* tag 'linux_kselftest-fixes-6.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/shuah/linux-kselftest:
kselftest/harness: Use helper to avoid zero-size memset warning
selftests/ftrace: Test toplevel-enable for instance
selftests/ftrace: traceonoff_triggers: strip off names
The dma_alloc_coherent() allocates a dma-mapped buffer, pbl->pg_arr[i].
The dma_free_coherent() should pass the same buffer to
dma_free_coherent() and not page-aligned.
Fixes: 1ac5a4047975 ("RDMA/bnxt_re: Add bnxt_re RoCE driver")
Signed-off-by: Thomas Fourier <fourier.thomas@gmail.com>
Link: https://patch.msgid.link/20251230085121.8023-2-fourier.thomas@gmail.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Pull block fixes from Jens Axboe:
- Scan partition tables asynchronously for ublk, similarly to how nvme
does it. This avoids potential deadlocks, which is why nvme does it
that way too. Includes a set of selftests as well.
- MD pull request via Yu:
- Fix null-pointer dereference in raid5 sysfs group_thread_cnt
store (Tuo Li)
- Fix possible mempool corruption during raid1 raid_disks update
via sysfs (FengWei Shih)
- Fix logical_block_size configuration being overwritten during
super_1_validate() (Li Nan)
- Fix forward incompatibility with configurable logical block size:
arrays assembled on new kernels could not be assembled on older
kernels (v6.18 and before) due to non-zero reserved pad rejection
(Li Nan)
- Fix static checker warning about iterator not incremented (Li Nan)
- Skip CPU offlining notifications on unmapped hardware queues
- bfq-iosched block stats fix
- Fix outdated comment in bfq-iosched
* tag 'block-6.19-20260102' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux:
block, bfq: update outdated comment
blk-mq: skip CPU offline notify on unmapped hctx
selftests/ublk: fix Makefile to rebuild on header changes
selftests/ublk: add test for async partition scan
ublk: scan partition in async way
block,bfq: fix aux stat accumulation destination
md: Fix forward incompatibility from configurable logical block size
md: Fix logical_block_size configuration being overwritten
md: suspend array while updating raid_disks via sysfs
md/raid5: fix possible null-pointer dereferences in raid5_store_group_thread_cnt()
md: Fix static checker warning in analyze_sbs
When building kselftests with a toolchain that enables source
fortification (e.g., Android's build environment, which uses
-D_FORTIFY_SOURCE=3), a build failure occurs in tests that use an
empty FIXTURE().
The root cause is that an empty fixture struct results in
`sizeof(self_private)` evaluating to 0. The compiler's fortification
checks then detect the `memset()` call with a compile-time constant size
of 0, issuing a `-Wuser-defined-warnings` which is promoted to an error
by `-Werror`.
An initial attempt to guard the call with `if (sizeof(self_private) > 0)`
was insufficient. The compiler's static analysis is aggressive enough
to flag the `memset(..., 0)` pattern before evaluating the conditional,
thus still triggering the error.
To resolve this robustly, this change introduces a `static inline`
helper function, `__kselftest_memset_safe()`. This function wraps the
size check and the `memset()` call. By replacing the direct `memset()`
in the `__TEST_F_IMPL` macro with a call to this helper, we create an
abstraction boundary. This prevents the compiler's static analyzer from
"seeing" the problematic pattern at the macro expansion site, resolving
the build failure.
Build Context:
Compiler: Android (14488419, +pgo, +bolt, +lto, +mlgo, based on r584948) clang version 22.0.0 (https://android.googlesource.com/toolchain/llvm-project 2d65e4108033380e6fe8e08b1f1826cd2bfb0c99)
Relevant Options: -O2 -Wall -Werror -D_FORTIFY_SOURCE=3 -target i686-linux-android10000
Test: m kselftest_futex_futex_requeue_pi
Removed Gerrit Change-Id
Shuah Khan <skhan@linuxfoundation.org>
Link: https://lore.kernel.org/r/20251224084120.249417-1-wakel@google.com
Signed-off-by: Wake Liu <wakel@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
If device max_mr_size bits in the range [mr_page_shift+31:mr_page_shift]
are zero, the `min3` function will set clt_path::max_pages_per_mr to
zero.
`alloc_path_reqs` will pass zero, which is invalid, as the third parameter
to `ib_alloc_mr`.
Fixes: 6a98d71daea1 ("RDMA/rtrs: client: main functionality")
Signed-off-by: Honggang LI <honggangli@163.com>
Link: https://patch.msgid.link/20251229025617.13241-1-honggangli@163.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Pull io_uring fixes from Jens Axboe:
- Removed dead argument length for io_uring_validate_mmap_request()
- Use GFP_NOWAIT for overflow CQEs on legacy ring setups rather than
GFP_ATOMIC, which makes it play nicer with memcg limits
- Fix a potential circular locking issue with tctx node removal and
exec based cancelations
* tag 'io_uring-6.19-20260102' of git://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux:
io_uring/memmap: drop unused sz param in io_uring_validate_mmap_request()
io_uring/tctx: add separate lock for list of tctx's in ctx
io_uring: use GFP_NOWAIT for overflow CQEs on legacy rings
The function bfq_bfqq_may_idle() was renamed as bfq_better_to_idle()
in commit 277a4a9b56cd ("block, bfq: give a better name to
bfq_bfqq_may_idle"). Update the comment accordingly.
Signed-off-by: Julia Lawall <Julia.Lawall@inria.fr>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
'available_events' is actually not required by
'test.d/event/toplevel-enable.tc' and its Existence has been tested in
'test.d/00basic/basic4.tc'.
So the require of 'available_events' can be dropped and then we can add
'instance' flag to test 'test.d/event/toplevel-enable.tc' for instance.
Test result show as below:
# ./ftracetest test.d/event/toplevel-enable.tc
=== Ftrace unit tests ===
[1] event tracing - enable/disable with top level files [PASS]
[2] (instance) event tracing - enable/disable with top level files [PASS]
# of passed: 2
# of failed: 0
# of unresolved: 0
# of untested: 0
# of unsupported: 0
# of xfailed: 0
# of undefined(test bug): 0
Link: https://lore.kernel.org/r/20230509203659.1173917-1-zhengyejian1@huawei.com
Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
rxe_odp_map_range_and_lock() must release umem_odp->umem_mutex when an
error occurs, including cases where rxe_check_pagefault() fails.
Fixes: 2fae67ab63db ("RDMA/rxe: Add support for Send/Recv/Write/Read with ODP")
Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
Link: https://patch.msgid.link/20251226094112.3042583-1-lizhijian@fujitsu.com
Reviewed-by: Zhu Yanjun <yanjun.zhu@linux.dev>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Pull x86 fix from Ingo Molnar:
"Fix the AMD microcode Entrysign signature checking code to include
more models"
* tag 'x86-urgent-2026-01-02' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
x86/microcode/AMD: Fix Entrysign revision check for Zen5/Strix Halo
io_uring_validate_mmap_request() doesn't use its size_t sz argument, so
remove it.
Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Pull MD fixes from Yu Kuai:
"- Fix null-pointer dereference in raid5 sysfs group_thread_cnt store
(Tuo Li)
- Fix possible mempool corruption during raid1 raid_disks update via
sysfs (FengWei Shih)
- Fix logical_block_size configuration being overwritten during
super_1_validate() (Li Nan)
- Fix forward incompatibility with configurable logical block size:
arrays assembled on new kernels could not be assembled on kernels
<=6.18 due to non-zero reserved pad rejection (Li Nan)
- Fix static checker warning about iterator not incremented (Li Nan)"
* tag 'md-6.19-20251231' of gitolite.kernel.org:pub/scm/linux/kernel/git/mdraid/linux:
md: Fix forward incompatibility from configurable logical block size
md: Fix logical_block_size configuration being overwritten
md: suspend array while updating raid_disks via sysfs
md/raid5: fix possible null-pointer dereferences in raid5_store_group_thread_cnt()
md: Fix static checker warning in analyze_sbs
The func_traceonoff_triggers.tc sometimes goes to fail
on my board, Kunpeng-920.
[root@localhost]# ./ftracetest ./test.d/ftrace/func_traceonoff_triggers.tc -l fail.log
=== Ftrace unit tests ===
[1] ftrace - test for function traceon/off triggers [FAIL]
[2] (instance) ftrace - test for function traceon/off triggers [UNSUPPORTED]
I look up the log, and it shows that the md5sum is different between csum1 and csum2.
++ cnt=611
++ sleep .1
+++ cnt_trace
+++ grep -v '^#' trace
+++ wc -l
++ cnt2=611
++ '[' 611 -ne 611 ']'
+++ cat tracing_on
++ on=0
++ '[' 0 '!=' 0 ']'
+++ md5sum trace
++ csum1='76896aa74362fff66a6a5f3cf8a8a500 trace'
++ sleep .1
+++ md5sum trace
++ csum2='ee8625a21c058818fc26e45c1ed3f6de trace'
++ '[' '76896aa74362fff66a6a5f3cf8a8a500 trace' '!=' 'ee8625a21c058818fc26e45c1ed3f6de trace' ']'
++ fail 'Tracing file is still changing'
++ echo Tracing file is still changing
Tracing file is still changing
++ exit_fail
++ exit 1
So I directly dump the trace file before md5sum, the diff shows that:
[root@localhost]# diff trace_1.log trace_2.log -y --suppress-common-lines
dockerd-12285 [036] d.... 18385.510290: sched_stat | <...>-12285 [036] d.... 18385.510290: sched_stat
dockerd-12285 [036] d.... 18385.510291: sched_swit | <...>-12285 [036] d.... 18385.510291: sched_swit
<...>-740 [044] d.... 18385.602859: sched_stat | kworker/44:1-740 [044] d.... 18385.602859: sched_stat
<...>-740 [044] d.... 18385.602860: sched_swit | kworker/44:1-740 [044] d.... 18385.602860: sched_swit
And we can see that <...> filed be filled with names.
We can strip off the names there to fix that.
After strip off the names:
kworker/u257:0-12 [019] d..2. 2528.758910: sched_stat | -12 [019] d..2. 2528.758910: sched_stat_runtime: comm=k
kworker/u257:0-12 [019] d..2. 2528.758912: sched_swit | -12 [019] d..2. 2528.758912: sched_switch: prev_comm=kw
<idle>-0 [000] d.s5. 2528.762318: sched_waki | -0 [000] d.s5. 2528.762318: sched_waking: comm=sshd pi
<idle>-0 [037] dNh2. 2528.762326: sched_wake | -0 [037] dNh2. 2528.762326: sched_wakeup: comm=sshd pi
<idle>-0 [037] d..2. 2528.762334: sched_swit | -0 [037] d..2. 2528.762334: sched_switch: prev_comm=sw
Link: https://lore.kernel.org/r/20230818013226.2182299-1-zouyipeng@huawei.com
Fixes: d87b29179aa0 ("selftests: ftrace: Use md5sum to take less time of checking logs")
Suggested-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Yipeng Zou <zouyipeng@huawei.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
In bnxt_qplib_alloc_init_hwq(), while allocating memory for PDE table
driver incorrectly is using the "pg_size" value passed to the function.
Fixed to use the right value 4K. Also, fixed the allocation size for
PBL table.
Fixes: 0c4dcd602817 ("RDMA/bnxt_re: Refactor hardware queue memory allocation")
Signed-off-by: Damodharam Ammepalli <damodharam.ammepalli@broadcom.com>
Signed-off-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Link: https://patch.msgid.link/20251223131855.145955-1-kalesh-anakkur.purayil@broadcom.com
Reviewed-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Leon Romanovsky <leon@kernel.org>
Pull LoongArch fixes from Huacai Chen:
"Complete CPUCFG registers definition, set correct protection_map[] for
VM_NONE/VM_SHARED, fix some bugs in the orc stack unwinder, ftrace and
BPF JIT"
* tag 'loongarch-fixes-6.19-1' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson:
samples/ftrace: Adjust LoongArch register restore order in direct calls
LoongArch: BPF: Enhance the bpf_arch_text_poke() function
LoongArch: BPF: Enable trampoline-based tracing for module functions
LoongArch: BPF: Adjust the jump offset of tail calls
LoongArch: BPF: Save return address register ra to t0 before trampoline
LoongArch: BPF: Zero-extend bpf_tail_call() index
LoongArch: BPF: Sign extend kfunc call arguments
LoongArch: Refactor register restoration in ftrace_common_return
LoongArch: Enable exception fixup for specific ADE subcode
LoongArch: Remove unnecessary checks for ORC unwinder
LoongArch: Remove is_entry_func() and kernel_entry_end
LoongArch: Use UNWIND_HINT_END_OF_STACK for entry points
LoongArch: Set correct protection_map[] for VM_NONE/VM_SHARED
LoongArch: Complete CPUCFG registers definition