Pull documentation updates from Jonathan Corbet:
"A slightly calmer cycle for docs this time around, though there is
still a fair amount going on, including:
- Some signs of life on the long-moribund Japanese translation
- Documentation on policies around the use of generative tools for
patch submissions, and a separate document intended for consumption
by generative tools
- The completion of the move of the documentation tools to
tools/docs. For now we're leaving a /scripts/kernel-doc symlink
behind to avoid breaking scripts
- Ongoing build-system work includes the incorporation of
documentation in Python code, better support for documenting
variables, and lots of improvements and fixes
- Automatic linking of man-page references -- cat(1), for example --
to the online pages in the HTML build
...and the usual array of typo fixes and such"
* tag 'docs-7.0' of git://git.kernel.org/pub/scm/linux/kernel/git/docs/linux: (107 commits)
doc: development-process: add notice on testing
tools: sphinx-build-wrapper: improve its help message
docs: sphinx-build-wrapper: allow -v override -q
docs: kdoc: Fix pdfdocs build for tools
docs: ja_JP: process: translate 'Obtain a current source tree'
docs: fix 're-use' -> 'reuse' in documentation
docs: ioctl-number: fix a typo in ioctl-number.rst
docs: filesystems: ensure proc pid substitutable is complete
docs: automarkup.py: Skip common English words as C identifiers
Documentation: use a source-read extension for the index link boilerplate
docs: parse_features: make documentation more consistent
docs: add parse_features module documentation
docs: jobserver: do some documentation improvements
docs: add jobserver module documentation
docs: kabi: helpers: add documentation for each "enum" value
docs: kabi: helpers: add helper for debug bits 7 and 8
docs: kabi: system_symbols: end docstring phrases with a dot
docs: python: abi_regex: do some improvements at documentation
docs: python: abi_parser: do some improvements at documentation
docs: add kabi modules documentation
...
vsprintf.c uses a mix of the `kernel.kptr_restrict` sysctl and the
`hash_pointers` boot param to control pointer hashing. But that wasn't
possible to tell without looking at the source code.
They have a different focus and purpose. To avoid wasting the time of
users trying to use one instead of the other, simply have them reference
each other in the Documentation.
Signed-off-by: Marc Herbert <marc.herbert@linux.intel.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <20260107-doc-hash-ptr-v2-1-cb4c161218d7@linux.intel.com>
Patch series "Enable hung_task and lockup cases to dump system info on
demand", v2.
When working on kernel stability issues: panic, task-hung and soft/hard
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, ftrace dump, etc.
panic case already uses sys_info() for this purpose, and has a
'panic_sys_info' sysctl(also support cmdline setup) interface to take
human readable string like "tasks,mem,timers,locks,ftrace,..." to control
what kinds of information is needed. Which is also helpful to debug
task-hung and lockup cases.
So this patchset introduces the similar sys_info sysctl interface for
task-hung and lockup cases.
his is mainly for debugging and the info dumping could be intrusive, like
dumping call stack for all tasks when system has huge number of tasks,
similarly for ftrace dump (we may add tracing_stop() and tracing_start()
around it)
Locally these have been used in our bug chasing for stability issues and
were helpful.
As Andrew suggested, add a configurable global 'kernel_sys_info' knob.
When error scenarios like panic/hung-task/lockup etc doesn't setup their
own sys_info knob and calls sys_info() with parameter "0", this global
knob will take effect. It could be used for other kernel cases like OOM,
which may not need one dedicated sys_info knob.
This patch (of 4):
Some sys_info names wered forgotten to change in patch iterations, while
the right names are defined in kernel/sys_info.c.
Link: https://lkml.kernel.org/r/20251113111039.22701-1-feng.tang@linux.alibaba.com
Link: https://lkml.kernel.org/r/20251113111039.22701-2-feng.tang@linux.alibaba.com
Fixes: d747755917 ("panic: add 'panic_sys_info' sysctl to take human readable string parameter")
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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
...
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()
...
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
...
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>
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>
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>
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
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>
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
...
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>
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>
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
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
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
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>
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>
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>
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
...
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
...
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>
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
...
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
...
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
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
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>
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()
...
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>
