Commit graph

110 commits

Author SHA1 Message Date
Linus Torvalds
e991acf1bc Significant patch series in this pull request:
- The 2 patch series "squashfs: Remove page->mapping references" from
   Matthew Wilcox gets us closer to being able to remove page->mapping.
 
 - The 5 patch series "relayfs: misc changes" from Jason Xing does some
   maintenance and minor feature addition work in relayfs.
 
 - The 5 patch series "kdump: crashkernel reservation from CMA" from 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.
 
 - The 5 patch series "generalize panic_print's dump function to be used
   by other kernel parts" from Feng Tang implements some consolidation and
   rationalizatio of the various ways in which a faiing kernel splats
   information at the operator.
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Merge tag 'mm-nonmm-stable-2025-08-03-12-47' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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
  ...
2025-08-03 16:23:09 -07:00
Linus Torvalds
b1cce98493 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.
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Merge tag 'docs-6.17' of git://git.lwn.net/linux

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=<dir>
  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()
  ...
2025-07-31 08:36:51 -07:00
Linus Torvalds
4b290aae78 Summary
* 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.
 
 * Testing
 
   All these have been in linux-next since rc3, giving them a solid 3 to 4 weeks
   worth of testing. Additionally, sysctl selftests and kunit were also run
   locally on my x86_64
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Merge tag 'sysctl-6.17-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/sysctl/sysctl

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
  ...
2025-07-29 21:43:08 -07:00
Joel Granados
ffc137c5c1 docs: Downgrade arm64 & riscv from titles to comment
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 <joel.granados@kernel.org>
2025-07-23 11:57:05 +02:00
Kees Cook
57fbad15c2 stackleak: Rename STACKLEAK to KSTACK_ERASE
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 <mingo@kernel.org>
Link: https://lore.kernel.org/r/20250717232519.2984886-1-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
2025-07-21 21:35:01 -07:00
Feng Tang
d747755917 panic: add 'panic_sys_info' sysctl to take human readable string parameter
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 <feng.tang@linux.alibaba.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-07-19 19:08:24 -07:00
Feng Tang
261743b013 panic: clean up code for console replay
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 <feng.tang@linux.alibaba.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: John Ogness <john.ogness@linutronix.de>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-07-19 19:08:24 -07:00
Breno Leitao
2a1390c813 docs: kernel: Clarify printk_ratelimit_burst reset behavior
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 <leitao@debian.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20250714-docs_ratelimit-v1-1-51a6d9071f1a@debian.org
2025-07-17 13:47:27 -06:00
Salvatore Bonaccorso
0400a541ba Documentation/sysctl: coredump: add %F for pidfd number
In commit b5325b2a27 ("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 <carnil@debian.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20250612060204.1159734-1-carnil@debian.org
2025-06-21 14:20:46 -06:00
Kees Cook
39ec9eaaa1 coredump: Only sort VMAs when core_sort_vma sysctl is set
The sorting of VMAs by size in commit 7d442a33bf ("binfmt_elf: Dump
smaller VMAs first in ELF cores") breaks elfutils[1]. Instead, sort
based on the setting of the new sysctl, core_sort_vma, which defaults
to 0, no sorting.

Reported-by: Michael Stapelberg <michael@stapelberg.ch>
Closes: https://lore.kernel.org/all/20250218085407.61126-1-michael@stapelberg.de/ [1]
Fixes: 7d442a33bf ("binfmt_elf: Dump smaller VMAs first in ELF cores")
Signed-off-by: Kees Cook <kees@kernel.org>
2025-02-24 10:51:57 -08:00
Phil Auld
e129fdc599 Documentation/sysctl: Add timer_migration to kernel.rst
There is no mention of timer_migration in the docs. Add
a short description.

Signed-off-by: Phil Auld <pauld@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20250114190525.169022-1-pauld@redhat.com
2025-01-16 11:18:04 -07:00
Lance Yang
62bf7065cc hung_task: add docs for hung_task_detect_count
This commit introduces documentation for hung_task_detect_count in
kernel.rst.

Link: https://lkml.kernel.org/r/20241027120747.42833-3-ioworker0@gmail.com
Signed-off-by: Mingzhe Yang <mingzhe.yang@ly.com>
Signed-off-by: Lance Yang <ioworker0@gmail.com>
Cc: Bang Li <libang.li@antgroup.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Huang Cun <cunhuang@tencent.com>
Cc: Joel Granados <j.granados@samsung.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: John Siddle <jsiddle@redhat.com>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Thomas Weißschuh <linux@weissschuh.net>
Cc: Yongliang Gao <leonylgao@tencent.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-11-11 17:17:03 -08:00
Helge Deller
cbade82334 parisc: Add support for CONFIG_SYSCTL_ARCH_UNALIGN_NO_WARN
Allow users to disable kernel warnings for unaligned memory
accesses from kernel via the /proc/sys/kernel/ignore-unaligned-usertrap
procfs entry.
That way users can disable those warnings in case they happen too
often.

Signed-off-by: Helge Deller <deller@gmx.de>
2024-07-24 02:04:05 +02:00
Linus Torvalds
ad584d73a2 Tracing updates for 6.9:
Main user visible change:
 
 - User events can now have "multi formats"
 
   The current user events have a single format. If another event is created
   with a different format, it will fail to be created. That is, once an
   event name is used, it cannot be used again with a different format. This
   can cause issues if a library is using an event and updates its format.
   An application using the older format will prevent an application using
   the new library from registering its event.
 
   A task could also DOS another application if it knows the event names, and
   it creates events with different formats.
 
   The multi-format event is in a different name space from the single
   format. Both the event name and its format are the unique identifier.
   This will allow two different applications to use the same user event name
   but with different payloads.
 
 - Added support to have ftrace_dump_on_oops dump out instances and
   not just the main top level tracing buffer.
 
 Other changes:
 
 - Add eventfs_root_inode
 
   Only the root inode has a dentry that is static (never goes away) and
   stores it upon creation. There's no reason that the thousands of other
   eventfs inodes should have a pointer that never gets set in its
   descriptor. Create a eventfs_root_inode desciptor that has a eventfs_inode
   descriptor and a dentry pointer, and only the root inode will use this.
 
 - Added WARN_ON()s in eventfs
 
   There's some conditionals remaining in eventfs that should never be hit,
   but instead of removing them, add WARN_ON() around them to make sure that
   they are never hit.
 
 - Have saved_cmdlines allocation also include the map_cmdline_to_pid array
 
   The saved_cmdlines structure allocates a large amount of data to hold its
   mappings. Within it, it has three arrays. Two are already apart of it:
   map_pid_to_cmdline[] and saved_cmdlines[]. More memory can be saved by
   also including the map_cmdline_to_pid[] array as well.
 
 - Restructure __string() and __assign_str() macros used in TRACE_EVENT().
 
   Dynamic strings in TRACE_EVENT() are declared with:
 
       __string(name, source)
 
   And assigned with:
 
      __assign_str(name, source)
 
   In the tracepoint callback of the event, the __string() is used to get the
   size needed to allocate on the ring buffer and __assign_str() is used to
   copy the string into the ring buffer. There's a helper structure that is
   created in the TRACE_EVENT() macro logic that will hold the string length
   and its position in the ring buffer which is created by __string().
 
   There are several trace events that have a function to create the string
   to save. This function is executed twice. Once for __string() and again
   for __assign_str(). There's no reason for this. The helper structure could
   also save the string it used in __string() and simply copy that into
   __assign_str() (it also already has its length).
 
   By using the structure to store the source string for the assignment, it
   means that the second argument to __assign_str() is no longer needed.
 
   It will be removed in the next merge window, but for now add a warning if
   the source string given to __string() is different than the source string
   given to __assign_str(), as the source to __assign_str() isn't even used
   and will be going away.
 
 - Added checks to make sure that the source of __string() is also the
   source of __assign_str() so that it can be safely removed in the next
   merge window.
 
   Included fixes that the above check found.
 
 - Other minor clean ups and fixes
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Merge tag 'trace-v6.9-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing updates from Steven Rostedt:
 "Main user visible change:

   - User events can now have "multi formats"

     The current user events have a single format. If another event is
     created with a different format, it will fail to be created. That
     is, once an event name is used, it cannot be used again with a
     different format. This can cause issues if a library is using an
     event and updates its format. An application using the older format
     will prevent an application using the new library from registering
     its event.

     A task could also DOS another application if it knows the event
     names, and it creates events with different formats.

     The multi-format event is in a different name space from the single
     format. Both the event name and its format are the unique
     identifier. This will allow two different applications to use the
     same user event name but with different payloads.

   - Added support to have ftrace_dump_on_oops dump out instances and
     not just the main top level tracing buffer.

  Other changes:

   - Add eventfs_root_inode

     Only the root inode has a dentry that is static (never goes away)
     and stores it upon creation. There's no reason that the thousands
     of other eventfs inodes should have a pointer that never gets set
     in its descriptor. Create a eventfs_root_inode desciptor that has a
     eventfs_inode descriptor and a dentry pointer, and only the root
     inode will use this.

   - Added WARN_ON()s in eventfs

     There's some conditionals remaining in eventfs that should never be
     hit, but instead of removing them, add WARN_ON() around them to
     make sure that they are never hit.

   - Have saved_cmdlines allocation also include the map_cmdline_to_pid
     array

     The saved_cmdlines structure allocates a large amount of data to
     hold its mappings. Within it, it has three arrays. Two are already
     apart of it: map_pid_to_cmdline[] and saved_cmdlines[]. More memory
     can be saved by also including the map_cmdline_to_pid[] array as
     well.

   - Restructure __string() and __assign_str() macros used in
     TRACE_EVENT()

     Dynamic strings in TRACE_EVENT() are declared with:

         __string(name, source)

     And assigned with:

        __assign_str(name, source)

     In the tracepoint callback of the event, the __string() is used to
     get the size needed to allocate on the ring buffer and
     __assign_str() is used to copy the string into the ring buffer.
     There's a helper structure that is created in the TRACE_EVENT()
     macro logic that will hold the string length and its position in
     the ring buffer which is created by __string().

     There are several trace events that have a function to create the
     string to save. This function is executed twice. Once for
     __string() and again for __assign_str(). There's no reason for
     this. The helper structure could also save the string it used in
     __string() and simply copy that into __assign_str() (it also
     already has its length).

     By using the structure to store the source string for the
     assignment, it means that the second argument to __assign_str() is
     no longer needed.

     It will be removed in the next merge window, but for now add a
     warning if the source string given to __string() is different than
     the source string given to __assign_str(), as the source to
     __assign_str() isn't even used and will be going away.

   - Added checks to make sure that the source of __string() is also the
     source of __assign_str() so that it can be safely removed in the
     next merge window.

     Included fixes that the above check found.

   - Other minor clean ups and fixes"

* tag 'trace-v6.9-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (34 commits)
  tracing: Add __string_src() helper to help compilers not to get confused
  tracing: Use strcmp() in __assign_str() WARN_ON() check
  tracepoints: Use WARN() and not WARN_ON() for warnings
  tracing: Use div64_u64() instead of do_div()
  tracing: Support to dump instance traces by ftrace_dump_on_oops
  tracing: Remove second parameter to __assign_rel_str()
  tracing: Add warning if string in __assign_str() does not match __string()
  tracing: Add __string_len() example
  tracing: Remove __assign_str_len()
  ftrace: Fix most kernel-doc warnings
  tracing: Decrement the snapshot if the snapshot trigger fails to register
  tracing: Fix snapshot counter going between two tracers that use it
  tracing: Use EVENT_NULL_STR macro instead of open coding "(null)"
  tracing: Use ? : shortcut in trace macros
  tracing: Do not calculate strlen() twice for __string() fields
  tracing: Rework __assign_str() and __string() to not duplicate getting the string
  cxl/trace: Properly initialize cxl_poison region name
  net: hns3: tracing: fix hclgevf trace event strings
  drm/i915: Add missing ; to __assign_str() macros in tracepoint code
  NFSD: Fix nfsd_clid_class use of __string_len() macro
  ...
2024-03-18 15:11:44 -07:00
Huang Yiwei
19f0423fd5 tracing: Support to dump instance traces by ftrace_dump_on_oops
Currently ftrace only dumps the global trace buffer on an OOPs. For
debugging a production usecase, instance trace will be helpful to
check specific problems since global trace buffer may be used for
other purposes.

This patch extend the ftrace_dump_on_oops parameter to dump a specific
or multiple trace instances:

  - ftrace_dump_on_oops=0: as before -- don't dump
  - ftrace_dump_on_oops[=1]: as before -- dump the global trace buffer
  on all CPUs
  - ftrace_dump_on_oops=2 or =orig_cpu: as before -- dump the global
  trace buffer on CPU that triggered the oops
  - ftrace_dump_on_oops=<instance_name>: new behavior -- dump the
  tracing instance matching <instance_name>
  - ftrace_dump_on_oops[=2/orig_cpu],<instance1_name>[=2/orig_cpu],
  <instrance2_name>[=2/orig_cpu]: new behavior -- dump the global trace
  buffer and multiple instance buffer on all CPUs, or only dump on CPU
  that triggered the oops if =2 or =orig_cpu is given

Also, the sysctl node can handle the input accordingly.

Link: https://lore.kernel.org/linux-trace-kernel/20240223083126.1817731-1-quic_hyiwei@quicinc.com

Cc: Ross Zwisler <zwisler@google.com>
Cc: <mhiramat@kernel.org>
Cc: <mark.rutland@arm.com>
Cc: <mcgrof@kernel.org>
Cc: <keescook@chromium.org>
Cc: <j.granados@samsung.com>
Cc: <mathieu.desnoyers@efficios.com>
Cc: <corbet@lwn.net>
Signed-off-by: Huang Yiwei <quic_hyiwei@quicinc.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2024-03-18 10:33:06 -04:00
Feng Tang
2e3fc6ca52 panic: add option to dump blocked tasks in panic_print
For debugging kernel panics and other bugs, there is already an option of
panic_print to dump all tasks' call stacks.  On today's large servers
running many containers, there could be thousands of tasks or more, and
this will print out huge amount of call stacks, taking a lot of time (for
serial console which is main target user case of panic_print).

And in many cases, only those several tasks being blocked are key for the
panic, so add an option to only dump blocked tasks' call stacks.

[akpm@linux-foundation.org: clarify documentation a little]
Link: https://lkml.kernel.org/r/20240202132042.3609657-1-feng.tang@intel.com
Signed-off-by: Feng Tang <feng.tang@intel.com>
Tested-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-02-22 15:38:55 -08:00
Alexey Gladkov
9220066ea8 docs: add information about ipc sysctls limitations
After 25b21cb2f6 ("[PATCH] IPC namespace core") and 4e9823111b
("[PATCH] IPC namespace - shm") the shared memory page count stopped being
global and started counting per ipc namespace.  The documentation and
shmget(2) still says that shmall is a global option.

shmget(2):

SHMALL System-wide limit on the total amount of shared memory, measured in
units of the system page size.  On Linux, this limit can be read and
modified via /proc/sys/kernel/shmall.

I think the changes made in 2006 should be documented.

Link: https://lkml.kernel.org/r/09e99911071766958af488beb4e8a728a4f12135.1705333426.git.legion@kernel.org
Signed-off-by: Alexey Gladkov <legion@kernel.org>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Link: https://lkml.kernel.org/r/ede20ddf7be48b93e8084c3be2e920841ee1a641.1663756794.git.legion@kernel.org
Cc: Christian Brauner <brauner@kernel.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Joel Granados <joel.granados@gmail.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-02-22 15:38:52 -08:00
Linus Torvalds
1e0c505e13 asm-generic updates for v6.7
The ia64 architecture gets its well-earned retirement as planned,
 now that there is one last (mostly) working release that will
 be maintained as an LTS kernel.
 
 The architecture specific system call tables are updated for
 the added map_shadow_stack() syscall and to remove references
 to the long-gone sys_lookup_dcookie() syscall.
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Merge tag 'asm-generic-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic

Pull ia64 removal and asm-generic updates from Arnd Bergmann:

 - The ia64 architecture gets its well-earned retirement as planned,
   now that there is one last (mostly) working release that will be
   maintained as an LTS kernel.

 - The architecture specific system call tables are updated for the
   added map_shadow_stack() syscall and to remove references to the
   long-gone sys_lookup_dcookie() syscall.

* tag 'asm-generic-6.7' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/asm-generic:
  hexagon: Remove unusable symbols from the ptrace.h uapi
  asm-generic: Fix spelling of architecture
  arch: Reserve map_shadow_stack() syscall number for all architectures
  syscalls: Cleanup references to sys_lookup_dcookie()
  Documentation: Drop or replace remaining mentions of IA64
  lib/raid6: Drop IA64 support
  Documentation: Drop IA64 from feature descriptions
  kernel: Drop IA64 support from sig_fault handlers
  arch: Remove Itanium (IA-64) architecture
2023-11-01 15:28:33 -10:00
Shrikanth Hegde
8f833c82cd sched/topology: Change behaviour of the 'sched_energy_aware' sysctl, based on the platform
The 'sched_energy_aware' sysctl is available for the admin to disable/enable
energy aware scheduling(EAS). EAS is enabled only if few conditions are
met by the platform. They are, asymmetric CPU capacity, no SMT,
schedutil CPUfreq governor, frequency invariant load tracking etc.
A platform may boot without EAS capability, but could gain such
capability at runtime. For example, changing/registering the cpufreq
governor to schedutil.

At present, though platform doesn't support EAS, this sysctl returns 1
and it ends up calling build_perf_domains on write to 1 and
NOP when writing to 0. That is confusing and un-necessary.

Desired behavior would be to have this sysctl to enable/disable the EAS
on supported platform. On non-supported platform write to the sysctl
would return not supported error and read of the sysctl would return
empty. So sched_energy_aware returns empty - EAS is not possible at this moment
This will include EAS capable platforms which have at least one EAS
condition false during startup, e.g. not using the schedutil cpufreq governor
sched_energy_aware returns 0 - EAS is supported but disabled by admin.
sched_energy_aware returns 1 - EAS is supported and enabled.

User can find out the reason why EAS is not possible by checking
info messages. sched_is_eas_possible returns true if the platform
can do EAS at this moment.

Signed-off-by: Shrikanth Hegde <sshegde@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Pierre Gondois <pierre.gondois@arm.com>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20231009060037.170765-3-sshegde@linux.vnet.ibm.com
2023-10-09 17:24:44 +02:00
Ard Biesheuvel
944834901a Documentation: Drop or replace remaining mentions of IA64
Drop or update mentions of IA64, as appropriate.

Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
2023-09-11 08:13:18 +00:00
Linus Torvalds
7ccc3ebf0c io_uring-6.6-2023-09-08
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Merge tag 'io_uring-6.6-2023-09-08' of git://git.kernel.dk/linux

Pull io_uring fixes from Jens Axboe:
 "A few fixes that should go into the 6.6-rc merge window:

   - Fix for a regression this merge window caused by the SQPOLL
     affinity patch, where we can race with SQPOLL thread shutdown and
     cause an oops when trying to set affinity (Gabriel)

   - Fix for a regression this merge window where fdinfo reading with
     for a ring setup with IORING_SETUP_NO_SQARRAY will attempt to
     deference the non-existing SQ ring array (me)

   - Add the patch that allows more finegrained control over who can use
     io_uring (Matteo)

   - Locking fix for a regression added this merge window for IOPOLL
     overflow (Pavel)

   - IOPOLL fix for stable, breaking our loop if helper threads are
     exiting (Pavel)

  Also had a fix for unreaped iopoll requests from io-wq from Ming, but
  we found an issue with that and hence it got reverted. Will get this
  sorted for a future rc"

* tag 'io_uring-6.6-2023-09-08' of git://git.kernel.dk/linux:
  Revert "io_uring: fix IO hang in io_wq_put_and_exit from do_exit()"
  io_uring: fix unprotected iopoll overflow
  io_uring: break out of iowq iopoll on teardown
  io_uring: add a sysctl to disable io_uring system-wide
  io_uring/fdinfo: only print ->sq_array[] if it's there
  io_uring: fix IO hang in io_wq_put_and_exit from do_exit()
  io_uring: Don't set affinity on a dying sqpoll thread
2023-09-08 21:32:28 -07:00
Matteo Rizzo
76d3ccecfa io_uring: add a sysctl to disable io_uring system-wide
Introduce a new sysctl (io_uring_disabled) which can be either 0, 1, or
2. When 0 (the default), all processes are allowed to create io_uring
instances, which is the current behavior.  When 1, io_uring creation is
disabled (io_uring_setup() will fail with -EPERM) for unprivileged
processes not in the kernel.io_uring_group group.  When 2, calls to
io_uring_setup() fail with -EPERM regardless of privilege.

Signed-off-by: Matteo Rizzo <matteorizzo@google.com>
[JEM: modified to add io_uring_group]
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Link: https://lore.kernel.org/r/x49y1i42j1z.fsf@segfault.boston.devel.redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2023-09-05 08:34:07 -06:00
Alexandre Ghiti
57972127b2
Documentation: admin-guide: Add riscv sysctl_perf_user_access
riscv now uses this sysctl so document its usage for this architecture.

Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
2023-08-16 07:28:21 -07:00
Jonathan Corbet
e4624435f3 docs: arm64: Move arm64 documentation under Documentation/arch/
Architecture-specific documentation is being moved into Documentation/arch/
as a way of cleaning up the top-level documentation directory and making
the docs hierarchy more closely match the source hierarchy.  Move
Documentation/arm64 into arch/ (along with the Chinese equvalent
translations) and fix up documentation references.

Cc: Will Deacon <will@kernel.org>
Cc: Alex Shi <alexs@kernel.org>
Cc: Hu Haowen <src.res@email.cn>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Yantengsi <siyanteng@loongson.cn>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2023-06-21 08:51:51 -06:00
Jonathan Corbet
ff61f0791c docs: move x86 documentation into Documentation/arch/
Move the x86 documentation under Documentation/arch/ as a way of cleaning
up the top-level directory and making the structure of our docs more
closely match the structure of the source directories it describes.

All in-kernel references to the old paths have been updated.

Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: linux-arch@vger.kernel.org
Cc: x86@kernel.org
Cc: Borislav Petkov <bp@alien8.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/lkml/20230315211523.108836-1-corbet@lwn.net/
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2023-03-30 12:58:51 -06:00
Ricardo Ribalda
a42aaad2e4 kexec: introduce sysctl parameters kexec_load_limit_*
kexec allows replacing the current kernel with a different one.  This is
usually a source of concerns for sysadmins that want to harden a system.

Linux already provides a way to disable loading new kexec kernel via
kexec_load_disabled, but that control is very coard, it is all or nothing
and does not make distinction between a panic kexec and a normal kexec.

This patch introduces new sysctl parameters, with finer tuning to specify
how many times a kexec kernel can be loaded.  The sysadmin can set
different limits for kexec panic and kexec reboot kernels.  The value can
be modified at runtime via sysctl, but only with a stricter value.

With these new parameters on place, a system with loadpin and verity
enabled, using the following kernel parameters:
sysctl.kexec_load_limit_reboot=0 sysct.kexec_load_limit_panic=1 can have a
good warranty that if initrd tries to load a panic kernel, a malitious
user will have small chances to replace that kernel with a different one,
even if they can trigger timeouts on the disk where the panic kernel
lives.

Link: https://lkml.kernel.org/r/20221114-disable-kexec-reset-v6-3-6a8531a09b9a@chromium.org
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Guilherme G. Piccoli <gpiccoli@igalia.com> # Steam Deck
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Philipp Rudo <prudo@redhat.com>
Cc: Ross Zwisler <zwisler@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-02 22:50:05 -08:00
Ricardo Ribalda
06dcb0138f Documentation: sysctl: correct kexec_load_disabled
Patch series "kexec: Add new parameter to limit the access to kexec", v6.

Add two parameter to specify how many times a kexec kernel can be loaded.

These parameter allow hardening the system.

While we are at it, fix a documentation issue and refactor some code.


This patch (of 3):

kexec_load_disabled affects both ``kexec_load`` and ``kexec_file_load``
syscalls. Make it explicit.

Link: https://lkml.kernel.org/r/20221114-disable-kexec-reset-v6-0-6a8531a09b9a@chromium.org
Link: https://lkml.kernel.org/r/20221114-disable-kexec-reset-v6-1-6a8531a09b9a@chromium.org
Signed-off-by: Ricardo Ribalda <ribalda@chromium.org>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Guilherme G. Piccoli <gpiccoli@igalia.com>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Philipp Rudo <prudo@redhat.com>
Cc: Ross Zwisler <zwisler@kernel.org>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-02-02 22:50:04 -08:00
Linus Torvalds
2f26e42455 LoongArch changes for v6.2
1, Switch to relative exception tables;
 2, Add unaligned access support;
 3, Add alternative runtime patching mechanism;
 4, Add FDT booting support from efi system table;
 5, Add suspend/hibernation (ACPI S3/S4) support;
 6, Add basic STACKPROTECTOR support;
 7, Add ftrace (function tracer) support;
 8, Update the default config file.
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Merge tag 'loongarch-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson

Pull LoongArch updates from Huacai Chen:

 - Switch to relative exception tables

 - Add unaligned access support

 - Add alternative runtime patching mechanism

 - Add FDT booting support from efi system table

 - Add suspend/hibernation (ACPI S3/S4) support

 - Add basic STACKPROTECTOR support

 - Add ftrace (function tracer) support

 - Update the default config file

* tag 'loongarch-6.2' of git://git.kernel.org/pub/scm/linux/kernel/git/chenhuacai/linux-loongson: (24 commits)
  LoongArch: Update Loongson-3 default config file
  LoongArch: modules/ftrace: Initialize PLT at load time
  LoongArch/ftrace: Add HAVE_FUNCTION_GRAPH_RET_ADDR_PTR support
  LoongArch/ftrace: Add HAVE_DYNAMIC_FTRACE_WITH_ARGS support
  LoongArch/ftrace: Add HAVE_DYNAMIC_FTRACE_WITH_REGS support
  LoongArch/ftrace: Add dynamic function graph tracer support
  LoongArch/ftrace: Add dynamic function tracer support
  LoongArch/ftrace: Add recordmcount support
  LoongArch/ftrace: Add basic support
  LoongArch: module: Use got/plt section indices for relocations
  LoongArch: Add basic STACKPROTECTOR support
  LoongArch: Add hibernation (ACPI S4) support
  LoongArch: Add suspend (ACPI S3) support
  LoongArch: Add processing ISA Node in DeviceTree
  LoongArch: Add FDT booting support from efi system table
  LoongArch: Use alternative to optimize libraries
  LoongArch: Add alternative runtime patching mechanism
  LoongArch: Add unaligned access support
  LoongArch: BPF: Add BPF exception tables
  LoongArch: Remove the .fixup section usage
  ...
2022-12-19 08:23:27 -06:00
Linus Torvalds
48ea09cdda hardening updates for v6.2-rc1
- Convert flexible array members, fix -Wstringop-overflow warnings,
   and fix KCFI function type mismatches that went ignored by
   maintainers (Gustavo A. R. Silva, Nathan Chancellor, Kees Cook).
 
 - Remove the remaining side-effect users of ksize() by converting
   dma-buf, btrfs, and coredump to using kmalloc_size_roundup(),
   add more __alloc_size attributes, and introduce full testing
   of all allocator functions. Finally remove the ksize() side-effect
   so that each allocation-aware checker can finally behave without
   exceptions.
 
 - Introduce oops_limit (default 10,000) and warn_limit (default off)
   to provide greater granularity of control for panic_on_oops and
   panic_on_warn (Jann Horn, Kees Cook).
 
 - Introduce overflows_type() and castable_to_type() helpers for
   cleaner overflow checking.
 
 - Improve code generation for strscpy() and update str*() kern-doc.
 
 - Convert strscpy and sigphash tests to KUnit, and expand memcpy
   tests.
 
 - Always use a non-NULL argument for prepare_kernel_cred().
 
 - Disable structleak plugin in FORTIFY KUnit test (Anders Roxell).
 
 - Adjust orphan linker section checking to respect CONFIG_WERROR
   (Xin Li).
 
 - Make sure siginfo is cleared for forced SIGKILL (haifeng.xu).
 
 - Fix um vs FORTIFY warnings for always-NULL arguments.
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Merge tag 'hardening-v6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull kernel hardening updates from Kees Cook:

 - Convert flexible array members, fix -Wstringop-overflow warnings, and
   fix KCFI function type mismatches that went ignored by maintainers
   (Gustavo A. R. Silva, Nathan Chancellor, Kees Cook)

 - Remove the remaining side-effect users of ksize() by converting
   dma-buf, btrfs, and coredump to using kmalloc_size_roundup(), add
   more __alloc_size attributes, and introduce full testing of all
   allocator functions. Finally remove the ksize() side-effect so that
   each allocation-aware checker can finally behave without exceptions

 - Introduce oops_limit (default 10,000) and warn_limit (default off) to
   provide greater granularity of control for panic_on_oops and
   panic_on_warn (Jann Horn, Kees Cook)

 - Introduce overflows_type() and castable_to_type() helpers for cleaner
   overflow checking

 - Improve code generation for strscpy() and update str*() kern-doc

 - Convert strscpy and sigphash tests to KUnit, and expand memcpy tests

 - Always use a non-NULL argument for prepare_kernel_cred()

 - Disable structleak plugin in FORTIFY KUnit test (Anders Roxell)

 - Adjust orphan linker section checking to respect CONFIG_WERROR (Xin
   Li)

 - Make sure siginfo is cleared for forced SIGKILL (haifeng.xu)

 - Fix um vs FORTIFY warnings for always-NULL arguments

* tag 'hardening-v6.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: (31 commits)
  ksmbd: replace one-element arrays with flexible-array members
  hpet: Replace one-element array with flexible-array member
  um: virt-pci: Avoid GCC non-NULL warning
  signal: Initialize the info in ksignal
  lib: fortify_kunit: build without structleak plugin
  panic: Expose "warn_count" to sysfs
  panic: Introduce warn_limit
  panic: Consolidate open-coded panic_on_warn checks
  exit: Allow oops_limit to be disabled
  exit: Expose "oops_count" to sysfs
  exit: Put an upper limit on how often we can oops
  panic: Separate sysctl logic from CONFIG_SMP
  mm/pgtable: Fix multiple -Wstringop-overflow warnings
  mm: Make ksize() a reporting-only function
  kunit/fortify: Validate __alloc_size attribute results
  drm/sti: Fix return type of sti_{dvo,hda,hdmi}_connector_mode_valid()
  drm/fsl-dcu: Fix return type of fsl_dcu_drm_connector_mode_valid()
  driver core: Add __alloc_size hint to devm allocators
  overflow: Introduce overflows_type() and castable_to_type()
  coredump: Proactively round up to kmalloc bucket size
  ...
2022-12-14 12:20:00 -08:00
Huacai Chen
61a6fccc0b LoongArch: Add unaligned access support
Loongson-2 series (Loongson-2K500, Loongson-2K1000) don't support
unaligned access in hardware, while Loongson-3 series (Loongson-3A5000,
Loongson-3C5000) are configurable whether support unaligned access in
hardware. This patch add unaligned access emulation for those LoongArch
processors without hardware support.

Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
2022-12-14 08:36:11 +08:00
Linus Torvalds
8702f2c611 Non-MM patches for 6.2-rc1.
- A ptrace API cleanup series from Sergey Shtylyov
 
 - Fixes and cleanups for kexec from ye xingchen
 
 - nilfs2 updates from Ryusuke Konishi
 
 - squashfs feature work from Xiaoming Ni: permit configuration of the
   filesystem's compression concurrency from the mount command line.
 
 - A series from Akinobu Mita which addresses bound checking errors when
   writing to debugfs files.
 
 - A series from Yang Yingliang to address rapido memory leaks
 
 - A series from Zheng Yejian to address possible overflow errors in
   encode_comp_t().
 
 - And a whole shower of singleton patches all over the place.
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Merge tag 'mm-nonmm-stable-2022-12-12' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-MM updates from Andrew Morton:

 - A ptrace API cleanup series from Sergey Shtylyov

 - Fixes and cleanups for kexec from ye xingchen

 - nilfs2 updates from Ryusuke Konishi

 - squashfs feature work from Xiaoming Ni: permit configuration of the
   filesystem's compression concurrency from the mount command line

 - A series from Akinobu Mita which addresses bound checking errors when
   writing to debugfs files

 - A series from Yang Yingliang to address rapidio memory leaks

 - A series from Zheng Yejian to address possible overflow errors in
   encode_comp_t()

 - And a whole shower of singleton patches all over the place

* tag 'mm-nonmm-stable-2022-12-12' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (79 commits)
  ipc: fix memory leak in init_mqueue_fs()
  hfsplus: fix bug causing custom uid and gid being unable to be assigned with mount
  rapidio: devices: fix missing put_device in mport_cdev_open
  kcov: fix spelling typos in comments
  hfs: Fix OOB Write in hfs_asc2mac
  hfs: fix OOB Read in __hfs_brec_find
  relay: fix type mismatch when allocating memory in relay_create_buf()
  ocfs2: always read both high and low parts of dinode link count
  io-mapping: move some code within the include guarded section
  kernel: kcsan: kcsan_test: build without structleak plugin
  mailmap: update email for Iskren Chernev
  eventfd: change int to __u64 in eventfd_signal() ifndef CONFIG_EVENTFD
  rapidio: fix possible UAF when kfifo_alloc() fails
  relay: use strscpy() is more robust and safer
  cpumask: limit visibility of FORCE_NR_CPUS
  acct: fix potential integer overflow in encode_comp_t()
  acct: fix accuracy loss for input value of encode_comp_t()
  linux/init.h: include <linux/build_bug.h> and <linux/stringify.h>
  rapidio: rio: fix possible name leak in rio_register_mport()
  rapidio: fix possible name leaks when rio_add_device() fails
  ...
2022-12-12 17:28:58 -08:00
Linus Torvalds
a7cacfb068 This was a not-too-busy cycle for documentation; highlights include:
- The beginnings of a set of translations into Spanish, headed up by Carlos
   Bilbao.
 
 - More Chinese translations.
 
 - A change to the Sphinx "alabaster" theme by default for HTML generation.
   Unlike the previous default (Read the Docs), alabaster is shipped with
   Sphinx by default, reducing the number of other dependencies that need to
   be installed.  It also (IMO) produces a cleaner and more readable result.
 
 - The ability to render the documentation into the texinfo format
   (something Sphinx could always do, we just never wired it up until now).
 
 Plus the usual collection of typo fixes, build-warning fixes, and minor
 updates.
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Merge tag 'docs-6.2' of git://git.lwn.net/linux

Pull documentation updates from Jonathan Corbet:
 "This was a not-too-busy cycle for documentation; highlights include:

   - The beginnings of a set of translations into Spanish, headed up by
     Carlos Bilbao

   - More Chinese translations

   - A change to the Sphinx "alabaster" theme by default for HTML
     generation.

     Unlike the previous default (Read the Docs), alabaster is shipped
     with Sphinx by default, reducing the number of other dependencies
     that need to be installed. It also (IMO) produces a cleaner and
     more readable result.

   - The ability to render the documentation into the texinfo format
     (something Sphinx could always do, we just never wired it up until
     now)

  Plus the usual collection of typo fixes, build-warning fixes, and
  minor updates"

* tag 'docs-6.2' of git://git.lwn.net/linux: (67 commits)
  Documentation/features: Use loongarch instead of loong
  Documentation/features-refresh.sh: Only sed the beginning "arch" of ARCH_DIR
  docs/zh_CN: Fix '.. only::' directive's expression
  docs/sp_SP: Add memory-barriers.txt Spanish translation
  docs/zh_CN/LoongArch: Update links of LoongArch ISA Vol1 and ELF psABI
  docs/LoongArch: Update links of LoongArch ISA Vol1 and ELF psABI
  Documentation/features: Update feature lists for 6.1
  Documentation: Fixed a typo in bootconfig.rst
  docs/sp_SP: Add process coding-style translation
  docs/sp_SP: Add kernel-docs.rst Spanish translation
  docs: Create translations/sp_SP/process/, move submitting-patches.rst
  docs: Add book to process/kernel-docs.rst
  docs: Retire old resources from kernel-docs.rst
  docs: Update maintainer of kernel-docs.rst
  Documentation: riscv: Document the sv57 VM layout
  Documentation: USB: correct possessive "its" usage
  math64: fix kernel-doc return value warnings
  math64: add kernel-doc for DIV64_U64_ROUND_UP
  math64: favor kernel-doc from header files
  doc: add texinfodocs and infodocs targets
  ...
2022-12-12 17:18:50 -08:00
Kees Cook
9fc9e278a5 panic: Introduce warn_limit
Like oops_limit, add warn_limit for limiting the number of warnings when
panic_on_warn is not set.

Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: tangmeng <tangmeng@uniontech.com>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: Tiezhu Yang <yangtiezhu@loongson.cn>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: linux-doc@vger.kernel.org
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221117234328.594699-5-keescook@chromium.org
2022-12-02 13:04:44 -08:00
Kees Cook
de92f65719 exit: Allow oops_limit to be disabled
In preparation for keeping oops_limit logic in sync with warn_limit,
have oops_limit == 0 disable checking the Oops counter.

Cc: Jann Horn <jannh@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Huang Ying <ying.huang@intel.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: linux-doc@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
2022-12-02 13:04:39 -08:00
Jann Horn
d4ccd54d28 exit: Put an upper limit on how often we can oops
Many Linux systems are configured to not panic on oops; but allowing an
attacker to oops the system **really** often can make even bugs that look
completely unexploitable exploitable (like NULL dereferences and such) if
each crash elevates a refcount by one or a lock is taken in read mode, and
this causes a counter to eventually overflow.

The most interesting counters for this are 32 bits wide (like open-coded
refcounts that don't use refcount_t). (The ldsem reader count on 32-bit
platforms is just 16 bits, but probably nobody cares about 32-bit platforms
that much nowadays.)

So let's panic the system if the kernel is constantly oopsing.

The speed of oopsing 2^32 times probably depends on several factors, like
how long the stack trace is and which unwinder you're using; an empirically
important one is whether your console is showing a graphical environment or
a text console that oopses will be printed to.
In a quick single-threaded benchmark, it looks like oopsing in a vfork()
child with a very short stack trace only takes ~510 microseconds per run
when a graphical console is active; but switching to a text console that
oopses are printed to slows it down around 87x, to ~45 milliseconds per
run.
(Adding more threads makes this faster, but the actual oops printing
happens under &die_lock on x86, so you can maybe speed this up by a factor
of around 2 and then any further improvement gets eaten up by lock
contention.)

It looks like it would take around 8-12 days to overflow a 32-bit counter
with repeated oopsing on a multi-core X86 system running a graphical
environment; both me (in an X86 VM) and Seth (with a distro kernel on
normal hardware in a standard configuration) got numbers in that ballpark.

12 days aren't *that* short on a desktop system, and you'd likely need much
longer on a typical server system (assuming that people don't run graphical
desktop environments on their servers), and this is a *very* noisy and
violent approach to exploiting the kernel; and it also seems to take orders
of magnitude longer on some machines, probably because stuff like EFI
pstore will slow it down a ton if that's active.

Signed-off-by: Jann Horn <jannh@google.com>
Link: https://lore.kernel.org/r/20221107201317.324457-1-jannh@google.com
Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
Signed-off-by: Kees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20221117234328.594699-2-keescook@chromium.org
2022-12-01 08:50:38 -08:00
Oleksandr Natalenko
8603b6f586 core_pattern: add CPU specifier
Statistically, in a large deployment regular segfaults may indicate a CPU
issue.

Currently, it is not possible to find out what CPU the segfault happened
on.  There are at least two attempts to improve segfault logging with this
regard, but they do not help in case the logs rotate.

Hence, lets make sure it is possible to permanently record a CPU the task
ran on using a new core_pattern specifier.

Link: https://lkml.kernel.org/r/20220903064330.20772-1-oleksandr@redhat.com
Signed-off-by: Oleksandr Natalenko <oleksandr@redhat.com>
Suggested-by: Renaud Métrich <rmetrich@redhat.com>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Grzegorz Halat <ghalat@redhat.com>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Joel Savitz <jsavitz@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Laurent Dufour <ldufour@linux.ibm.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Rob Herring <robh@kernel.org>
Cc: Stephen Kitt <steve@sk2.org>
Cc: Will Deacon <will@kernel.org>
Cc: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-11-18 13:55:06 -08:00
Guilherme G. Piccoli
727209376f x86/split_lock: Add sysctl to control the misery mode
Commit b041b525da ("x86/split_lock: Make life miserable for split lockers")
changed the way the split lock detector works when in "warn" mode;
basically, it not only shows the warn message, but also intentionally
introduces a slowdown through sleeping plus serialization mechanism
on such task. Based on discussions in [0], seems the warning alone
wasn't enough motivation for userspace developers to fix their
applications.

This slowdown is enough to totally break some proprietary (aka.
unfixable) userspace[1].

Happens that originally the proposal in [0] was to add a new mode
which would warns + slowdown the "split locking" task, keeping the
old warn mode untouched. In the end, that idea was discarded and
the regular/default "warn" mode now slows down the applications. This
is quite aggressive with regards proprietary/legacy programs that
basically are unable to properly run in kernel with this change.
While it is understandable that a malicious application could DoS
by split locking, it seems unacceptable to regress old/proprietary
userspace programs through a default configuration that previously
worked. An example of such breakage was reported in [1].

Add a sysctl to allow controlling the "misery mode" behavior, as per
Thomas suggestion on [2]. This way, users running legacy and/or
proprietary software are allowed to still execute them with a decent
performance while still observing the warning messages on kernel log.

[0] https://lore.kernel.org/lkml/20220217012721.9694-1-tony.luck@intel.com/
[1] https://github.com/doitsujin/dxvk/issues/2938
[2] https://lore.kernel.org/lkml/87pmf4bter.ffs@tglx/

[ dhansen: minor changelog tweaks, including clarifying the actual
  	   problem ]

Fixes: b041b525da ("x86/split_lock: Make life miserable for split lockers")
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Reviewed-by: Tony Luck <tony.luck@intel.com>
Tested-by: Andre Almeida <andrealmeid@igalia.com>
Link: https://lore.kernel.org/all/20221024200254.635256-1-gpiccoli%40igalia.com
2022-11-10 10:14:22 -08:00
Stephen Kitt
aadc0cd52f docs: sysctl/fs: re-order, prettify
This brings the text markup in line with sysctl/abi and
sysctl/kernel:

* the entries are ordered alphabetically
* the table of contents is automatically generated
* markup is used as appropriate for constants etc.

The content isn't fully up-to-date but the obsolete entries are gone,
so remove the kernel version mention.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20220930102937.135841-6-steve@sk2.org
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2022-10-19 16:42:09 -06:00
Linus Torvalds
676cb49573 - hfs and hfsplus kmap API modernization from Fabio Francesco
- Valentin Schneider makes crash-kexec work properly when invoked from
   an NMI-time panic.
 
 - ntfs bugfixes from Hawkins Jiawei
 
 - Jiebin Sun improves IPC msg scalability by replacing atomic_t's with
   percpu counters.
 
 - nilfs2 cleanups from Minghao Chi
 
 - lots of other single patches all over the tree!
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Merge tag 'mm-nonmm-stable-2022-10-11' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull non-MM updates from Andrew Morton:

 - hfs and hfsplus kmap API modernization (Fabio Francesco)

 - make crash-kexec work properly when invoked from an NMI-time panic
   (Valentin Schneider)

 - ntfs bugfixes (Hawkins Jiawei)

 - improve IPC msg scalability by replacing atomic_t's with percpu
   counters (Jiebin Sun)

 - nilfs2 cleanups (Minghao Chi)

 - lots of other single patches all over the tree!

* tag 'mm-nonmm-stable-2022-10-11' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (71 commits)
  include/linux/entry-common.h: remove has_signal comment of arch_do_signal_or_restart() prototype
  proc: test how it holds up with mapping'less process
  mailmap: update Frank Rowand email address
  ia64: mca: use strscpy() is more robust and safer
  init/Kconfig: fix unmet direct dependencies
  ia64: update config files
  nilfs2: replace WARN_ONs by nilfs_error for checkpoint acquisition failure
  fork: remove duplicate included header files
  init/main.c: remove unnecessary (void*) conversions
  proc: mark more files as permanent
  nilfs2: remove the unneeded result variable
  nilfs2: delete unnecessary checks before brelse()
  checkpatch: warn for non-standard fixes tag style
  usr/gen_init_cpio.c: remove unnecessary -1 values from int file
  ipc/msg: mitigate the lock contention with percpu counter
  percpu: add percpu_counter_add_local and percpu_counter_sub_local
  fs/ocfs2: fix repeated words in comments
  relay: use kvcalloc to alloc page array in relay_alloc_page_array
  proc: make config PROC_CHILDREN depend on PROC_FS
  fs: uninline inode_maybe_inc_iversion()
  ...
2022-10-12 11:00:22 -07:00
Petr Vorel
bfca3dd3d0 kernel/utsname_sysctl.c: print kernel arch
Print the machine hardware name (UTS_MACHINE) in /proc/sys/kernel/arch.

This helps people who debug kernel with initramfs with minimal environment
(i.e.  without coreutils or even busybox) or allow to open sysfs file
instead of run 'uname -m' in high level languages.

Link: https://lkml.kernel.org/r/20220901194403.3819-1-pvorel@suse.cz
Signed-off-by: Petr Vorel <pvorel@suse.cz>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: David Sterba <dsterba@suse.com>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-09-11 21:55:12 -07:00
Huang Ying
c6833e1000 memory tiering: rate limit NUMA migration throughput
In NUMA balancing memory tiering mode, if there are hot pages in slow
memory node and cold pages in fast memory node, we need to promote/demote
hot/cold pages between the fast and cold memory nodes.

A choice is to promote/demote as fast as possible.  But the CPU cycles and
memory bandwidth consumed by the high promoting/demoting throughput will
hurt the latency of some workload because of accessing inflating and slow
memory bandwidth contention.

A way to resolve this issue is to restrict the max promoting/demoting
throughput.  It will take longer to finish the promoting/demoting.  But
the workload latency will be better.  This is implemented in this patch as
the page promotion rate limit mechanism.

The number of the candidate pages to be promoted to the fast memory node
via NUMA balancing is counted, if the count exceeds the limit specified by
the users, the NUMA balancing promotion will be stopped until the next
second.

A new sysctl knob kernel.numa_balancing_promote_rate_limit_MBps is added
for the users to specify the limit.

Link: https://lkml.kernel.org/r/20220713083954.34196-3-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: osalvador <osalvador@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zhong Jiang <zhongjiang-ali@linux.alibaba.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2022-09-11 20:25:54 -07:00
Linus Torvalds
cae4199f93 powerpc updates for 6.0
- Add support for syscall stack randomization.
 
  - Add support for atomic operations to the 32 & 64-bit BPF JIT.
 
  - Full support for KASAN on 64-bit Book3E.
 
  - Add a watchdog driver for the new PowerVM hypervisor watchdog.
 
  - Add a number of new selftests for the Power10 PMU support.
 
  - Add a driver for the PowerVM Platform KeyStore.
 
  - Increase the NMI watchdog timeout during live partition migration, to avoid timeouts
    due to increased memory access latency.
 
  - Add support for using the 'linux,pci-domain' device tree property for PCI domain
    assignment.
 
  - Many other small features and fixes.
 
 Thanks to: Alexey Kardashevskiy, Andy Shevchenko, Arnd Bergmann, Athira Rajeev, Bagas
 Sanjaya, Christophe Leroy, Erhard Furtner, Fabiano Rosas, Greg Kroah-Hartman, Greg Kurz,
 Haowen Bai, Hari Bathini, Jason A. Donenfeld, Jason Wang, Jiang Jian, Joel Stanley, Juerg
 Haefliger, Kajol Jain, Kees Cook, Laurent Dufour, Madhavan Srinivasan, Masahiro Yamada,
 Maxime Bizon, Miaoqian Lin, Murilo Opsfelder Araújo, Nathan Lynch, Naveen N. Rao, Nayna
 Jain, Nicholas Piggin, Ning Qiang, Pali Rohár, Petr Mladek, Rashmica Gupta, Sachin Sant,
 Scott Cheloha, Segher Boessenkool, Stephen Rothwell, Uwe Kleine-König, Wolfram Sang, Xiu
 Jianfeng, Zhouyi Zhou.
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Merge tag 'powerpc-6.0-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux

Pull powerpc updates from Michael Ellerman:

 - Add support for syscall stack randomization

 - Add support for atomic operations to the 32 & 64-bit BPF JIT

 - Full support for KASAN on 64-bit Book3E

 - Add a watchdog driver for the new PowerVM hypervisor watchdog

 - Add a number of new selftests for the Power10 PMU support

 - Add a driver for the PowerVM Platform KeyStore

 - Increase the NMI watchdog timeout during live partition migration, to
   avoid timeouts due to increased memory access latency

 - Add support for using the 'linux,pci-domain' device tree property for
   PCI domain assignment

 - Many other small features and fixes

Thanks to Alexey Kardashevskiy, Andy Shevchenko, Arnd Bergmann, Athira
Rajeev, Bagas Sanjaya, Christophe Leroy, Erhard Furtner, Fabiano Rosas,
Greg Kroah-Hartman, Greg Kurz, Haowen Bai, Hari Bathini, Jason A.
Donenfeld, Jason Wang, Jiang Jian, Joel Stanley, Juerg Haefliger, Kajol
Jain, Kees Cook, Laurent Dufour, Madhavan Srinivasan, Masahiro Yamada,
Maxime Bizon, Miaoqian Lin, Murilo Opsfelder Araújo, Nathan Lynch,
Naveen N.  Rao, Nayna Jain, Nicholas Piggin, Ning Qiang, Pali Rohár,
Petr Mladek, Rashmica Gupta, Sachin Sant, Scott Cheloha, Segher
Boessenkool, Stephen Rothwell, Uwe Kleine-König, Wolfram Sang, Xiu
Jianfeng, and Zhouyi Zhou.

* tag 'powerpc-6.0-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (191 commits)
  powerpc/64e: Fix kexec build error
  EDAC/ppc_4xx: Include required of_irq header directly
  powerpc/pci: Fix PHB numbering when using opal-phbid
  powerpc/64: Init jump labels before parse_early_param()
  selftests/powerpc: Avoid GCC 12 uninitialised variable warning
  powerpc/cell/axon_msi: Fix refcount leak in setup_msi_msg_address
  powerpc/xive: Fix refcount leak in xive_get_max_prio
  powerpc/spufs: Fix refcount leak in spufs_init_isolated_loader
  powerpc/perf: Include caps feature for power10 DD1 version
  powerpc: add support for syscall stack randomization
  powerpc: Move system_call_exception() to syscall.c
  powerpc/powernv: rename remaining rng powernv_ functions to pnv_
  powerpc/powernv/kvm: Use darn for H_RANDOM on Power9
  powerpc/powernv: Avoid crashing if rng is NULL
  selftests/powerpc: Fix matrix multiply assist test
  powerpc/signal: Update comment for clarity
  powerpc: make facility_unavailable_exception 64s
  powerpc/platforms/83xx/suspend: Remove write-only global variable
  powerpc/platforms/83xx/suspend: Prevent unloading the driver
  powerpc/platforms/83xx/suspend: Reorder to get rid of a forward declaration
  ...
2022-08-06 16:38:17 -07:00
Laurent Dufour
118b136693 powerpc/pseries/mobility: set NMI watchdog factor during an LPM
During an LPM, while the memory transfer is in progress on the arrival
side, some latencies are generated when accessing not yet transferred
pages on the arrival side. Thus, the NMI watchdog may be triggered too
frequently, which increases the risk to hit an NMI interrupt in a bad
place in the kernel, leading to a kernel panic.

Disabling the Hard Lockup Watchdog until the memory transfer could be a
too strong work around, some users would want this timeout to be
eventually triggered if the system is hanging even during an LPM.

Introduce a new sysctl variable nmi_watchdog_factor. It allows to apply
a factor to the NMI watchdog timeout during an LPM. Just before the CPUs
are stopped for the switchover sequence, the NMI watchdog timer is set
to watchdog_thresh + factor%

A value of 0 has no effect. The default value is 200, meaning that the
NMI watchdog is set to 30s during LPM (based on a 10s watchdog_thresh
value). Once the memory transfer is achieved, the factor is reset to 0.

Setting this value to a high number is like disabling the NMI watchdog
during an LPM.

Signed-off-by: Laurent Dufour <ldufour@linux.ibm.com>
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20220713154729.80789-5-ldufour@linux.ibm.com
2022-07-27 21:36:03 +10:00
Stephen Kitt
30fb876141 docs: admin-guide/sysctl: Fix rendering error
Text in ``literal`` markup must be separated by word separators, so text
like ``lowwater``% renders incorrectly.  Add the suggested "\ " after two
problematic occurrences.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20220624110230.595740-1-steve@sk2.org
[jc: tweaked to use "\ "]
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2022-06-24 13:07:37 -06:00
Linus Torvalds
88a618920e It was a moderately busy cycle for documentation; highlights include:
- After a long period of inactivity, the Japanese translations are seeing
    some much-needed maintenance and updating.
 
  - Reworked IOMMU documentation
 
  - Some new documentation for static-analysis tools
 
  - A new overall structure for the memory-management documentation.  This
    is an LSFMM outcome that, it is hoped, will help encourage developers to
    fill in the many gaps.  Optimism is eternal...but hopefully it will
    work.
 
  - More Chinese translations.
 
 Plus the usual typo fixes, updates, etc.
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Merge tag 'docs-5.19' of git://git.lwn.net/linux

Pull documentation updates from Jonathan Corbet:
 "It was a moderately busy cycle for documentation; highlights include:

   - After a long period of inactivity, the Japanese translations are
     seeing some much-needed maintenance and updating.

   - Reworked IOMMU documentation

   - Some new documentation for static-analysis tools

   - A new overall structure for the memory-management documentation.
     This is an LSFMM outcome that, it is hoped, will help encourage
     developers to fill in the many gaps. Optimism is eternal...but
     hopefully it will work.

   - More Chinese translations.

  Plus the usual typo fixes, updates, etc"

* tag 'docs-5.19' of git://git.lwn.net/linux: (70 commits)
  docs: pdfdocs: Add space for chapter counts >= 100 in TOC
  docs/zh_CN: Add dev-tools/gdb-kernel-debugging.rst Chinese translation
  input: Docs: correct ntrig.rst typo
  input: Docs: correct atarikbd.rst typos
  MAINTAINERS: Become the docs/zh_CN maintainer
  docs/zh_CN: fix devicetree usage-model translation
  mm,doc: Add new documentation structure
  Documentation: drop more IDE boot options and ide-cd.rst
  Documentation/process: use scripts/get_maintainer.pl on patches
  MAINTAINERS: Add entry for DOCUMENTATION/JAPANESE
  docs/trans/ja_JP/howto: Don't mention specific kernel versions
  docs/ja_JP/SubmittingPatches: Request summaries for commit references
  docs/ja_JP/SubmittingPatches: Add Suggested-by as a standard signature
  docs/ja_JP/SubmittingPatches: Randy has moved
  docs/ja_JP/SubmittingPatches: Suggest the use of scripts/get_maintainer.pl
  docs/ja_JP/SubmittingPatches: Update GregKH links
  Documentation/sysctl: document max_rcu_stall_to_panic
  Documentation: add missing angle bracket in cgroup-v2 doc
  Documentation: dev-tools: use literal block instead of code-block
  docs/zh_CN: add vm numa translation
  ...
2022-05-25 11:17:41 -07:00
Jason A. Donenfeld
069c4ea687 random: fix sysctl documentation nits
A semicolon was missing, and the almost-alphabetical-but-not ordering
was confusing, so regroup these by category instead.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
2022-05-13 23:59:12 +02:00
Joel Savitz
81c653659d Documentation/sysctl: document max_rcu_stall_to_panic
commit dfe564045c ("rcu: Panic after fixed number of stalls")
introduced a new systctl but no accompanying documentation.

Add a simple entry to the documentation.

Signed-off-by: Joel Savitz <jsavitz@redhat.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2022-05-01 17:14:09 -06:00
Linus Torvalds
52deda9551 Merge branch 'akpm' (patches from Andrew)
Merge more updates from Andrew Morton:
 "Various misc subsystems, before getting into the post-linux-next
  material.

  41 patches.

  Subsystems affected by this patch series: procfs, misc, core-kernel,
  lib, checkpatch, init, pipe, minix, fat, cgroups, kexec, kdump,
  taskstats, panic, kcov, resource, and ubsan"

* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (41 commits)
  Revert "ubsan, kcsan: Don't combine sanitizer with kcov on clang"
  kernel/resource: fix kfree() of bootmem memory again
  kcov: properly handle subsequent mmap calls
  kcov: split ioctl handling into locked and unlocked parts
  panic: move panic_print before kmsg dumpers
  panic: add option to dump all CPUs backtraces in panic_print
  docs: sysctl/kernel: add missing bit to panic_print
  taskstats: remove unneeded dead assignment
  kasan: no need to unset panic_on_warn in end_report()
  ubsan: no need to unset panic_on_warn in ubsan_epilogue()
  panic: unset panic_on_warn inside panic()
  docs: kdump: add scp example to write out the dump file
  docs: kdump: update description about sysfs file system support
  arm64: mm: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef
  x86/setup: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef
  riscv: mm: init: use IS_ENABLED(CONFIG_KEXEC_CORE) instead of #ifdef
  kexec: make crashk_res, crashk_low_res and crash_notes symbols always visible
  cgroup: use irqsave in cgroup_rstat_flush_locked().
  fat: use pointer to simple type in put_user()
  minix: fix bug when opening a file with O_DIRECT
  ...
2022-03-24 14:14:07 -07:00
Guilherme G. Piccoli
8d470a45d1 panic: add option to dump all CPUs backtraces in panic_print
Currently the "panic_print" parameter/sysctl allows some interesting debug
information to be printed during a panic event.  This is useful for
example in cases the user cannot kdump due to resource limits, or if the
user collects panic logs in a serial output (or pstore) and prefers a fast
reboot instead of a kdump.

Happens that currently there's no way to see all CPUs backtraces in a
panic using "panic_print" on architectures that support that.  We do have
"oops_all_cpu_backtrace" sysctl, but although partially overlapping in the
functionality, they are orthogonal in nature: "panic_print" is a panic
tuning (and we have panics without oopses, like direct calls to panic() or
maybe other paths that don't go through oops_enter() function), and the
original purpose of "oops_all_cpu_backtrace" is to provide more
information on oopses for cases in which the users desire to continue
running the kernel even after an oops, i.e., used in non-panic scenarios.

So, we hereby introduce an additional bit for "panic_print" to allow
dumping the CPUs backtraces during a panic event.

Link: https://lkml.kernel.org/r/20211109202848.610874-3-gpiccoli@igalia.com
Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Reviewed-by: Feng Tang <feng.tang@intel.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-03-23 19:00:35 -07:00
Guilherme G. Piccoli
a1ff1de00d docs: sysctl/kernel: add missing bit to panic_print
Patch series "Some improvements on panic_print".

This is a mix of a documentation fix with some additions to the
"panic_print" syscall / parameter.  The goal here is being able to collect
all CPUs backtraces during a panic event and also to enable "panic_print"
in a kdump event - details of the reasoning and design choices in the
patches.

This patch (of 3):

Commit de6da1e8bc ("panic: add an option to replay all the printk
message in buffer") added a new bit to the sysctl/kernel parameter
"panic_print", but the documentation was added only in
kernel-parameters.txt, not in the sysctl guide.

Fix it here by adding bit 5 to sysctl admin-guide documentation.

[rdunlap@infradead.org: fix table format warning]
  Link: https://lkml.kernel.org/r/20220109055635.6999-1-rdunlap@infradead.org

Link: https://lkml.kernel.org/r/20211109202848.610874-1-gpiccoli@igalia.com
Link: https://lkml.kernel.org/r/20211109202848.610874-2-gpiccoli@igalia.com
Fixes: de6da1e8bc ("panic: add an option to replay all the printk message in buffer")
Signed-off-by: Guilherme G. Piccoli <gpiccoli@igalia.com>
Reviewed-by: Feng Tang <feng.tang@intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2022-03-23 19:00:35 -07:00