kernel/linux.git/Documentation/admin-guide/sysctl/kernel.rst, branch v6.18.21

panic: refine the document for 'panic_print'

2025-09-14T00:32:50+00:00

User reported current document about SYS_INFO_PANIC_CONSOLE_REPLAY is confusing, that people could expect all user space console messages to be replayed. Specify that only 'kernel' messages will be replayed to solve the confusion. Link: https://lkml.kernel.org/r/20250825025701.81921-3-feng.tang@linux.alibaba.com Signed-off-by: Feng Tang Reported-by: Askar Safin Reviewed-by: Petr Mladek Cc: John Ogness Cc: Jonathan Corbet Cc: Lance Yang Cc: "Paul E . McKenney" Cc: Steven Rostedt Signed-off-by: Andrew Morton

Merge tag 'mm-nonmm-stable-2025-08-03-12-47' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-08-03T23:23:09+00:00

Pull non-MM updates from Andrew Morton: "Significant patch series in this pull request: - "squashfs: Remove page->mapping references" (Matthew Wilcox) gets us closer to being able to remove page->mapping - "relayfs: misc changes" (Jason Xing) does some maintenance and minor feature addition work in relayfs - "kdump: crashkernel reservation from CMA" (Jiri Bohac) switches us from static preallocation of the kdump crashkernel's working memory over to dynamic allocation. So the difficulty of a-priori estimation of the second kernel's needs is removed and the first kernel obtains extra memory - "generalize panic_print's dump function to be used by other kernel parts" (Feng Tang) implements some consolidation and rationalization of the various ways in which a failing kernel splats information at the operator * tag 'mm-nonmm-stable-2025-08-03-12-47' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (80 commits) tools/getdelays: add backward compatibility for taskstats version kho: add test for kexec handover delaytop: enhance error logging and add PSI feature description samples: Kconfig: fix spelling mistake "instancess" -> "instances" fat: fix too many log in fat_chain_add() scripts/spelling.txt: add notifer||notifier to spelling.txt xen/xenbus: fix typo "notifer" net: mvneta: fix typo "notifer" drm/xe: fix typo "notifer" cxl: mce: fix typo "notifer" KVM: x86: fix typo "notifer" MAINTAINERS: add maintainers for delaytop ucount: use atomic_long_try_cmpxchg() in atomic_long_inc_below() ucount: fix atomic_long_inc_below() argument type kexec: enable CMA based contiguous allocation stackdepot: make max number of pools boot-time configurable lib/xxhash: remove unused functions init/Kconfig: restore CONFIG_BROKEN help text lib/raid6: update recov_rvv.c zero page usage docs: update docs after introducing delaytop ...

Merge tag 'docs-6.17' of git://git.lwn.net/linux

2025-07-31T15:36:51+00:00

Pull documentation updates from Jonathan Corbet: "It has been a relatively busy cycle for docs, especially the build system: - The Perl kernel-doc script was added to 2.3.52pre1 just after the turn of the millennium. Over the following 25 years, it accumulated a vast amount of cruft, all in a language few people want to deal with anymore. Mauro's Python replacement in 6.16 faithfully reproduced all of the cruft in the hope of avoiding regressions. Now that we have a more reasonable code base, though, we can work on cleaning it up; many of the changes this time around are toward that end. - A reorganization of the ext4 docs into the usual TOC format. - Various Chinese translations and updates. - A new script from Mauro to help with docs-build testing. - A new document for linked lists - A sweep through MAINTAINERS fixing broken GitHub git:// repository links. ...and lots of fixes and updates" * tag 'docs-6.17' of git://git.lwn.net/linux: (147 commits) scripts: add origin commit identification based on specific patterns sphinx: kernel_abi: fix performance regression with O= Documentation: core-api: entry: Replace deprecated KVM entry/exit functions docs: fault-injection: drop reference to md-faulty docs: document linked lists scripts: kdoc: make it backward-compatible with Python 3.7 docs: kernel-doc: emit warnings for ancient versions of Python Documentation/rtla: Describe exit status Documentation/rtla: Add include common_appendix.rst docs: kernel: Clarify printk_ratelimit_burst reset behavior Documentation: ioctl-number: Don't repeat macro names Documentation: ioctl-number: Shorten macros table Documentation: ioctl-number: Correct full path to papr-physical-attestation.h Documentation: ioctl-number: Extend "Include File" column width Documentation: ioctl-number: Fix linuxppc-dev mailto link overlayfs.rst: fix typos docs: kdoc: emit a warning for ancient versions of Python docs: kdoc: clean up check_sections() docs: kdoc: directly access the always-there KdocItem fields docs: kdoc: straighten up dump_declaration() ...

Merge tag 'sysctl-6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl

2025-07-30T04:43:08+00:00

Pull sysctl updates from Joel Granados: - Move sysctls out of the kern_table array This is the final move of ctl_tables into their respective subsystems. Only 5 (out of the original 50) will remain in kernel/sysctl.c file; these handle either sysctl or common arch variables. By decentralizing sysctl registrations, subsystem maintainers regain control over their sysctl interfaces, improving maintainability and reducing the likelihood of merge conflicts. - docs: Remove false positives from check-sysctl-docs Stopped falsely identifying sysctls as undocumented or unimplemented in the check-sysctl-docs script. This script can now be used to automatically identify if documentation is missing. * tag 'sysctl-6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl: (23 commits) docs: Downgrade arm64 & riscv from titles to comment docs: Replace spaces with tabs in check-sysctl-docs docs: Remove colon from ctltable title in vm.rst docs: Add awk section for ucount sysctl entries docs: Use skiplist when checking sysctl admin-guide docs: nixify check-sysctl-docs sysctl: rename kern_table -> sysctl_subsys_table kernel/sys.c: Move overflow{uid,gid} sysctl into kernel/sys.c uevent: mv uevent_helper into kobject_uevent.c sysctl: Removed unused variable sysctl: Nixify sysctl.sh sysctl: Remove superfluous includes from kernel/sysctl.c sysctl: Remove (very) old file changelog sysctl: Move sysctl_panic_on_stackoverflow to kernel/panic.c sysctl: move cad_pid into kernel/pid.c sysctl: Move tainted ctl_table into kernel/panic.c Input: sysrq: mv sysrq into drivers/tty/sysrq.c fork: mv threads-max into kernel/fork.c parisc/power: Move soft-power into power.c mm: move randomize_va_space into memory.c ...

docs: Downgrade arm64 & riscv from titles to comment

2025-07-23T09:57:05+00:00

Remove the title string ("====") from under arm64 & riscv and move them to a commment under the perf_user_access sysctl. They are explanations, *not* sysctls themselves This effectively removes these two strings from appearing as not implemented when the check-sysctl-docs script is run Signed-off-by: Joel Granados

stackleak: Rename STACKLEAK to KSTACK_ERASE

2025-07-22T04:35:01+00:00

In preparation for adding Clang sanitizer coverage stack depth tracking that can support stack depth callbacks: - Add the new top-level CONFIG_KSTACK_ERASE option which will be implemented either with the stackleak GCC plugin, or with the Clang stack depth callback support. - Rename CONFIG_GCC_PLUGIN_STACKLEAK as needed to CONFIG_KSTACK_ERASE, but keep it for anything specific to the GCC plugin itself. - Rename all exposed "STACKLEAK" names and files to "KSTACK_ERASE" (named for what it does rather than what it protects against), but leave as many of the internals alone as possible to avoid even more churn. While here, also split "prev_lowest_stack" into CONFIG_KSTACK_ERASE_METRICS, since that's the only place it is referenced from. Suggested-by: Ingo Molnar Link: https://lore.kernel.org/r/20250717232519.2984886-1-kees@kernel.org Signed-off-by: Kees Cook

panic: add 'panic_sys_info' sysctl to take human readable string parameter

2025-07-20T02:08:24+00:00

Bitmap definition for 'panic_print' is hard to remember and decode. Add 'panic_sys_info='sysctl to take human readable string like "tasks,mem,timers,locks,ftrace,..." and translate it into bitmap. The detailed mapping is: SYS_INFO_TASKS "tasks" SYS_INFO_MEM "mem" SYS_INFO_TIMERS "timers" SYS_INFO_LOCKS "locks" SYS_INFO_FTRACE "ftrace" SYS_INFO_ALL_CPU_BT "all_bt" SYS_INFO_BLOCKED_TASKS "blocked_tasks" [nathan@kernel.org: add __maybe_unused to sys_info_avail] Link: https://lkml.kernel.org/r/20250708-fix-clang-sys_info_avail-warning-v1-1-60d239eacd64@kernel.org Link: https://lkml.kernel.org/r/20250703021004.42328-4-feng.tang@linux.alibaba.com Signed-off-by: Feng Tang Suggested-by: Petr Mladek Cc: John Ogness Cc: Jonathan Corbet Cc: Lance Yang Cc: "Paul E . McKenney" Cc: Steven Rostedt Cc: Nathan Chancellor Cc: Andy Shevchenko Signed-off-by: Andrew Morton

panic: clean up code for console replay

2025-07-20T02:08:24+00:00

Patch series "generalize panic_print's dump function to be used by other kernel parts", v3. When working on kernel stability issues, panic, task-hung and software/hardware lockup are frequently met. And to debug them, user may need lots of system information at that time, like task call stacks, lock info, memory info etc. panic case already has panic_print_sys_info() for this purpose, and has a 'panic_print' bitmask to control what kinds of information is needed, which is also helpful to debug other task-hung and lockup cases. So this patchset extracts the function out to a new file 'lib/sys_info.c', and makes it available for other cases which also need to dump system info for debugging. Also as suggested by Petr Mladek, add 'panic_sys_info=' interface to take human readable string like "tasks,mem,locks,timers,ftrace,....", and eventually obsolete the current 'panic_print' bitmap interface. In RFC and V1 version, hung_task and SW/HW watchdog modules are enabled with the new sys_info dump interface. In v2, they are kept out for better review of current change, and will be posted later. Locally these have been used in our bug chasing for stability issues and was proven helpful. Many thanks to Petr Mladek for great suggestions on both the code and architectures! This patch (of 5): Currently the panic_print_sys_info() was called twice with different parameters to handle console replay case, which is kind of confusing. Add panic_console_replay() explicitly and rename 'PANIC_PRINT_ALL_PRINTK_MSG' to 'PANIC_CONSOLE_REPLAY', to make the code straightforward. The related kernel document is also updated. Link: https://lkml.kernel.org/r/20250703021004.42328-1-feng.tang@linux.alibaba.com Link: https://lkml.kernel.org/r/20250703021004.42328-2-feng.tang@linux.alibaba.com Signed-off-by: Feng Tang Suggested-by: Petr Mladek Reviewed-by: Petr Mladek Cc: John Ogness Cc: Jonathan Corbet Cc: Lance Yang Cc: "Paul E . McKenney" Cc: Steven Rostedt Cc: Nathan Chancellor Signed-off-by: Andrew Morton

docs: kernel: Clarify printk_ratelimit_burst reset behavior

2025-07-17T19:47:27+00:00

Add clarification that the printk_ratelimit_burst window resets after printk_ratelimit seconds have elapsed, allowing another burst of messages to be sent. This helps users understand that the rate limiting is not permanent but operates in periodic windows. Signed-off-by: Breno Leitao Reviewed-by: Paul E. McKenney Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20250714-docs_ratelimit-v1-1-51a6d9071f1a@debian.org

Documentation/sysctl: coredump: add %F for pidfd number

2025-06-21T20:20:46+00:00

In commit b5325b2a270f ("coredump: hand a pidfd to the usermode coredump helper") a new core_pattern specifier, %F, was added to provide a pidfs to the usermode helper process referring to the crashed process. Update the documentation to include the new core_pattern specifier. Signed-off-by: Salvatore Bonaccorso Signed-off-by: Jonathan Corbet Link: https://lore.kernel.org/r/20250612060204.1159734-1-carnil@debian.org