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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When /sys/kernel/tracing/buffer_size_kb is less than 12KB,
the test_multiple_writes test will stall and wait for more
input due to insufficient buffer space.
Check current buffer_size_kb value before the test. If it is
less than 12KB, it temporarily increase the buffer to 12KB,
and restore the original value after the tests are completed.
Link: https://lore.kernel.org/r/20260109033620.25727-1-fushuai.wang@linux.dev
Fixes: 37f46601383a ("selftests/tracing: Add basic test for trace_marker_raw file")
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Fushuai Wang <wangfushuai@baidu.com>
Acked-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>
Pull core entry fix from Borislav Petkov:
- Make sure clang inlines trivial local_irq_* helpers
* tag 'core_urgent_for_v6.19_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
entry: Always inline local_irq_{enable,disable}_exit_to_user()
Pull pmdomain fixes from Ulf Hansson:
- mediatek: Fix spinlock recursion fix during probe
- imx: Fix reference count leak during probe
* tag 'pmdomain-v6.19-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/ulfh/linux-pm:
pmdomain: imx: Fix reference count leak in imx_gpc_probe()
pmdomain: mtk-pm-domains: Fix spinlock recursion fix in probe
clang needs __always_inline instead of inline, even for tiny helpers.
This saves some cycles in system call fast path, and saves 195 bytes
on x86_64 build:
$ size vmlinux.before vmlinux.after
text data bss dec hex filename
34652814 22291961 5875180 62819955 3be8e73 vmlinux.before
34652619 22291961 5875180 62819760 3be8db0 vmlinux.after
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20251204153127.1321824-1-edumazet@google.com
Pull perf tool fixes and from Namhyung Kim:
- skip building BPF skeletons if libopenssl is missing
- a couple of test updates
- handle error cases of filename__read_build_id()
- support NVIDIA Olympus for ARM SPE profiling
- update tool headers to sync with the kernel
* tag 'perf-tools-fixes-for-v6.19-2026-01-02' of git://git.kernel.org/pub/scm/linux/kernel/git/perf/perf-tools:
tools build: Fix the common set of features test wrt libopenssl
tools headers: Sync syscall table with kernel sources
tools headers: Sync linux/socket.h with kernel sources
tools headers: Sync linux/gfp_types.h with kernel sources
tools headers: Sync arm64 headers with kernel sources
tools headers: Sync x86 headers with kernel sources
tools headers: Sync UAPI sound/asound.h with kernel sources
tools headers: Sync UAPI linux/mount.h with kernel sources
tools headers: Sync UAPI linux/fs.h with kernel sources
tools headers: Sync UAPI linux/fcntl.h with kernel sources
tools headers: Sync UAPI KVM headers with kernel sources
tools headers: Sync UAPI drm/drm.h with kernel sources
perf arm-spe: Add NVIDIA Olympus to neoverse list
tools headers arm64: Add NVIDIA Olympus part
perf tests top: Make the test exclusive
perf tests kvm: Avoid leaving perf.data.guest file around
perf symbol: Fix ENOENT case for filename__read_build_id
perf tools: Disable BPF skeleton if no libopenssl found
tools/build: Add a feature test for libopenssl
of_get_child_by_name() returns a node pointer with refcount incremented.
Use the __free() attribute to manage the pgc_node reference, ensuring
automatic of_node_put() cleanup when pgc_node goes out of scope.
This eliminates the need for explicit error handling paths and avoids
reference count leaks.
Fixes: 721cabf6c660 ("soc: imx: move PGC handling to a new GPC driver")
Cc: stable@vger.kernel.org
Signed-off-by: Wentao Liang <vulab@iscas.ac.cn>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Pull power management fix from Rafael Wysocki:
"Fix a recent regression that affects system suspend testing
at the 'core' level (Rafael Wysocki)"
* tag 'pm-6.19-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
PM: sleep: Fix suspend_test() at the TEST_CORE level
The recent introduction of the libopenssl feature test forgot to add the
-lssl to the test-all.o target, which made it always fail, fix it.
Noticed by looking at this file after building:
$ cat /tmp/build/perf-tools/feature/test-all.make.output
/usr/bin/ld: /tmp/ccBhO8WH.ltrans0.ltrans.o: in function `main':
/home/acme/git/perf-tools/tools/build/feature/test-libopenssl.c:6:(.text.startup+0x2ed): undefined reference to `OPENSSL_init_ssl'
collect2: error: ld returned 1 exit status
$
It was added only to the individual ssl test, that works:
$ cat /tmp/build/perf-tools/feature/test-libopenssl.make.output
$ ldd /tmp/build/perf-tools/feature/test-libopenssl.bin | grep ssl
libssl.so.3 => /usr/lib64/libssl.so.3 (0x00007fb81eda8000)
$
Fixes: 7678523109d1d9ee ("tools/build: Add a feature test for libopenssl")
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Remove scpsys_get_legacy_regmap(), replacing its usage with
of_find_node_with_property(). Explicitly call of_node_get(np) before each
of_find_node_with_property() to maintain correct node reference counting.
The of_find_node_with_property() function "consumes" its input by calling
of_node_put() internally, whether or not it finds a match. Currently,
dev->of_node (np) is passed multiple times in sequence without incrementing
its reference count, causing it to be decremented multiple times and
risking early memory release.
Adding of_node_get(np) before each call balances the reference count,
preventing premature node release.
Fixes: c1bac49fe91f ("pmdomains: mtk-pm-domains: Fix spinlock recursion in probe")
Cc: stable@vger.kernel.org
Signed-off-by: Macpaul Lin <macpaul.lin@mediatek.com>
Tested-by: Louis-Alexis Eyraud <louisalexis.eyraud@collabora.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Pull SCSI fixes from James Bottomley:
"The only core fix is in doc; all the others are in drivers, with the
biggest impacts in libsas being the rollback on error handling and in
ufs coming from a couple of error handling fixes, one causing a crash
if it's activated before scanning and the other fixing W-LUN
resumption"
* tag 'scsi-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi:
scsi: ufs: qcom: Fix confusing cleanup.h syntax
scsi: libsas: Add rollback handling when an error occurs
scsi: device_handler: Return error pointer in scsi_dh_attached_handler_name()
scsi: ufs: core: Fix a deadlock in the frequency scaling code
scsi: ufs: core: Fix an error handler crash
scsi: Revert "scsi: libsas: Fix exp-attached device scan after probe failure scanned in again after probe failed"
scsi: ufs: core: Fix RPMB link error by reversing Kconfig dependencies
scsi: qla4xxx: Use time conversion macros
scsi: qla2xxx: Enable/disable IRQD_NO_BALANCING during reset
scsi: ipr: Enable/disable IRQD_NO_BALANCING during reset
scsi: imm: Fix use-after-free bug caused by unfinished delayed work
scsi: target: sbp: Remove KMSG_COMPONENT macro
scsi: core: Correct documentation for scsi_device_quiesce()
scsi: mpi3mr: Prevent duplicate SAS/SATA device entries in channel 1
scsi: target: Reset t_task_cdb pointer in error case
scsi: ufs: core: Fix EH failure after W-LUN resume error
Pull crypto library fix from Eric Biggers:
"Fix the kunit_run_irq_test() function (which I recently added for the
CRC and crypto tests) to be less timing-dependent.
This fixes flakiness in the polyval kunit test suite"
* tag 'libcrypto-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiggers/linux:
kunit: Enforce task execution in {soft,hard}irq contexts
Commit a10ad1b10402 ("PM: suspend: Make pm_test delay interruptible by
wakeup events") replaced mdelay() in suspend_test() with msleep() which
does not work at the TEST_CORE test level that calls suspend_test()
while running on one CPU with interrupts off.
Address this by making suspend_test() check if the test level is
suitable for using msleep() and use mdelay() otherwise.
Fixes: a10ad1b10402 ("PM: suspend: Make pm_test delay interruptible by wakeup events")
Reported-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Closes: https://lore.kernel.org/linux-pm/aUsAk0k1N9hw8IkY@venus/
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Tested-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Link: https://patch.msgid.link/6251576.lOV4Wx5bFT@rafael.j.wysocki
To pick up changes from:
b36d4b6aa88ef039 ("arch: hookup listns() system call")
This should be used to beautify the syscall arguments and it addresses
these tools/perf build warnings:
Warning: Kernel ABI header differences:
diff -u tools/include/uapi/asm-generic/unistd.h include/uapi/asm-generic/unistd.h
diff -u tools/scripts/syscall.tbl scripts/syscall.tbl
diff -u tools/perf/arch/x86/entry/syscalls/syscall_32.tbl arch/x86/entry/syscalls/syscall_32.tbl
diff -u tools/perf/arch/x86/entry/syscalls/syscall_64.tbl arch/x86/entry/syscalls/syscall_64.tbl
diff -u tools/perf/arch/powerpc/entry/syscalls/syscall.tbl arch/powerpc/kernel/syscalls/syscall.tbl
diff -u tools/perf/arch/s390/entry/syscalls/syscall.tbl arch/s390/kernel/syscalls/syscall.tbl
diff -u tools/perf/arch/mips/entry/syscalls/syscall_n64.tbl arch/mips/kernel/syscalls/syscall_n64.tbl
diff -u tools/perf/arch/arm/entry/syscalls/syscall.tbl arch/arm/tools/syscall.tbl
diff -u tools/perf/arch/sh/entry/syscalls/syscall.tbl arch/sh/kernel/syscalls/syscall.tbl
diff -u tools/perf/arch/sparc/entry/syscalls/syscall.tbl arch/sparc/kernel/syscalls/syscall.tbl
diff -u tools/perf/arch/xtensa/entry/syscalls/syscall.tbl arch/xtensa/kernel/syscalls/syscall.tbl
Please see tools/include/uapi/README.
Note that s390 syscall table is still out of sync as it switches to use the
generic table. But I'd like to minimize the change in this commit.
Cc: linux-arch@vger.kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Pull ceph updates from Ilya Dryomov:
"We have a patch that adds an initial set of tracepoints to the MDS
client from Max, a fix that hardens osdmap parsing code from myself
(marked for stable) and a few assorted fixups"
* tag 'ceph-for-6.19-rc1' of https://github.com/ceph/ceph-client:
rbd: stop selecting CRC32, CRYPTO, and CRYPTO_AES
ceph: stop selecting CRC32, CRYPTO, and CRYPTO_AES
libceph: make decode_pool() more resilient against corrupted osdmaps
libceph: Amend checking to fix `make W=1` build breakage
ceph: Amend checking to fix `make W=1` build breakage
ceph: add trace points to the MDS client
libceph: fix log output race condition in OSD client