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When CONFIG_MEM_ALLOC_PROFILING_DEBUG=y, /proc/sys/vm/mem_profiling is
read-only to avoid debug warnings in a scenario when an allocation is
made while profiling is disabled (allocation does not get an allocation
tag), then profiling gets enabled and allocation gets freed (warning due
to the allocation missing allocation tag).
Link: https://lkml.kernel.org/r/20260116184423.2708363-1-surenb@google.com
Fixes: ebdf9ad4ca98 ("memprofiling: documentation")
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Acked-by: SeongJae Park <sj@kernel.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Ran Xiaokai <ran.xiaokai@zte.com.cn>
Cc: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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In blamed commit, I added a check against the temporary queue
built in __dev_xmit_skb(). Idea was to drop packets early,
before any spinlock was acquired.
if (unlikely(defer_count > READ_ONCE(q->limit))) {
kfree_skb_reason(skb, SKB_DROP_REASON_QDISC_DROP);
return NET_XMIT_DROP;
}
It turned out that HTB Qdisc has a zero q->limit.
HTB limits packets on a per-class basis.
Some of our tests became flaky.
Add a new sysctl : net.core.qdisc_max_burst to control
how many packets can be stored in the temporary lockless queue.
Also add a new QDISC_BURST_DROP drop reason to better diagnose
future issues.
Thanks Neal !
Fixes: 100dfa74cad9 ("net: dev_queue_xmit() llist adoption")
Reported-and-bisected-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Link: https://patch.msgid.link/20260107104159.3669285-1-edumazet@google.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull non-MM updates from Andrew Morton:
- "panic: sys_info: Refactor and fix a potential issue" (Andy Shevchenko)
fixes a build issue and does some cleanup in ib/sys_info.c
- "Implement mul_u64_u64_div_u64_roundup()" (David Laight)
enhances the 64-bit math code on behalf of a PWM driver and beefs up
the test module for these library functions
- "scripts/gdb/symbols: make BPF debug info available to GDB" (Ilya Leoshkevich)
makes BPF symbol names, sizes, and line numbers available to the GDB
debugger
- "Enable hung_task and lockup cases to dump system info on demand" (Feng Tang)
adds a sysctl which can be used to cause additional info dumping when
the hung-task and lockup detectors fire
- "lib/base64: add generic encoder/decoder, migrate users" (Kuan-Wei Chiu)
adds a general base64 encoder/decoder to lib/ and migrates several
users away from their private implementations
- "rbree: inline rb_first() and rb_last()" (Eric Dumazet)
makes TCP a little faster
- "liveupdate: Rework KHO for in-kernel users" (Pasha Tatashin)
reworks the KEXEC Handover interfaces in preparation for Live Update
Orchestrator (LUO), and possibly for other future clients
- "kho: simplify state machine and enable dynamic updates" (Pasha Tatashin)
increases the flexibility of KEXEC Handover. Also preparation for LUO
- "Live Update Orchestrator" (Pasha Tatashin)
is a major new feature targeted at cloud environments. Quoting the
cover letter:
This series introduces the Live Update Orchestrator, a kernel
subsystem designed to facilitate live kernel updates using a
kexec-based reboot. This capability is critical for cloud
environments, allowing hypervisors to be updated with minimal
downtime for running virtual machines. LUO achieves this by
preserving the state of selected resources, such as memory,
devices and their dependencies, across the kernel transition.
As a key feature, this series includes support for preserving
memfd file descriptors, which allows critical in-memory data, such
as guest RAM or any other large memory region, to be maintained in
RAM across the kexec reboot.
Mike Rappaport merits a mention here, for his extensive review and
testing work.
- "kexec: reorganize kexec and kdump sysfs" (Sourabh Jain)
moves the kexec and kdump sysfs entries from /sys/kernel/ to
/sys/kernel/kexec/ and adds back-compatibility symlinks which can
hopefully be removed one day
- "kho: fixes for vmalloc restoration" (Mike Rapoport)
fixes a BUG which was being hit during KHO restoration of vmalloc()
regions
* tag 'mm-nonmm-stable-2025-12-06-11-14' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (139 commits)
calibrate: update header inclusion
Reinstate "resource: avoid unnecessary lookups in find_next_iomem_res()"
vmcoreinfo: track and log recoverable hardware errors
kho: fix restoring of contiguous ranges of order-0 pages
kho: kho_restore_vmalloc: fix initialization of pages array
MAINTAINERS: TPM DEVICE DRIVER: update the W-tag
init: replace simple_strtoul with kstrtoul to improve lpj_setup
KHO: fix boot failure due to kmemleak access to non-PRESENT pages
Documentation/ABI: new kexec and kdump sysfs interface
Documentation/ABI: mark old kexec sysfs deprecated
kexec: move sysfs entries to /sys/kernel/kexec
test_kho: always print restore status
kho: free chunks using free_page() instead of kfree()
selftests/liveupdate: add kexec test for multiple and empty sessions
selftests/liveupdate: add simple kexec-based selftest for LUO
selftests/liveupdate: add userspace API selftests
docs: add documentation for memfd preservation via LUO
mm: memfd_luo: allow preserving memfd
liveupdate: luo_file: add private argument to store runtime state
mm: shmem: export some functions to internal.h
...
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Which serves as a global default sys_info mask. When users want the same
system information for many error cases (panic, hung, lockup ...), they
can chose to set this global knob only once, while not setting up each
individual sys_info knobs.
This just adds a 'lazy' option, and doesn't change existing kernel
behavior as the mask is 0 by default.
Link: https://lkml.kernel.org/r/20251113111039.22701-5-feng.tang@linux.alibaba.com
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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When soft/hard lockup happens, developers may need different kinds of
system information (call-stacks, memory info, locks, etc.) to help
debugging.
Add 'softlockup_sys_info' and 'hardlockup_sys_info' sysctl knobs to take
human readable string like "tasks,mem,timers,locks,ftrace,...", and when
system lockup happens, all requested information will be printed out.
(refer kernel/sys_info.c for more details).
Link: https://lkml.kernel.org/r/20251113111039.22701-4-feng.tang@linux.alibaba.com
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: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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When task-hung happens, developers may need different kinds of system
information (call-stacks, memory info, locks, etc.) to help debugging.
Add 'hung_task_sys_info' sysctl knob to take human readable string like
"tasks,mem,timers,locks,ftrace,...", and when task-hung happens, all
requested information will be dumped. (refer kernel/sys_info.c for more
details).
Meanwhile, the newly introduced sys_info() call is used to unify some
existing info-dumping knobs.
[feng.tang@linux.alibaba.com: maintain consistecy established behavior, per Lance and Petr]
Link: https://lkml.kernel.org/r/aRncJo1mA5Zk77Hr@U-2FWC9VHC-2323.local
Link: https://lkml.kernel.org/r/20251113111039.22701-3-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>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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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: d747755917bf ("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>
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The hung_task_panic sysctl is currently a blunt instrument: it's all or
nothing.
Panicking on a single hung task can be an overreaction to a transient
glitch. A more reliable indicator of a systemic problem is when
multiple tasks hang simultaneously.
Extend hung_task_panic to accept an integer threshold, allowing the
kernel to panic only when N hung tasks are detected in a single scan.
This provides finer control to distinguish between isolated incidents
and system-wide failures.
The accepted values are:
- 0: Don't panic (unchanged)
- 1: Panic on the first hung task (unchanged)
- N > 1: Panic after N hung tasks are detected in a single scan
The original behavior is preserved for values 0 and 1, maintaining full
backward compatibility.
[lance.yang@linux.dev: new changelog]
Link: https://lkml.kernel.org/r/20251015063615.2632-1-lirongqing@baidu.com
Signed-off-by: Li RongQing <lirongqing@baidu.com>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Tested-by: Lance Yang <lance.yang@linux.dev>
Acked-by: Andrew Jeffery <andrew@codeconstruct.com.au> [aspeed_g5_defconfig]
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Florian Wesphal <fw@strlen.de>
Cc: Jakub Kacinski <kuba@kernel.org>
Cc: Jason A. Donenfeld <jason@zx2c4.com>
Cc: Joel Granados <joel.granados@kernel.org>
Cc: Joel Stanley <joel@jms.id.au>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kees Cook <kees@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Phil Auld <pauld@redhat.com>
Cc: Randy Dunlap <rdunlap@infradead.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Simon Horman <horms@kernel.org>
Cc: Stanislav Fomichev <sdf@fomichev.me>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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skb_defer_max value is very conservative, and can be increased
to avoid too many calls to kick_defer_list_purge().
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Reviewed-by: Jason Xing <kerneljasonxing@gmail.com>
Link: https://patch.msgid.link/20251106202935.1776179-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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If a socket has sk->sk_bypass_prot_mem flagged, the socket opts out
of the global protocol memory accounting.
Let's control the flag by a new sysctl knob.
The flag is written once during socket(2) and is inherited to child
sockets.
Tested with a script that creates local socket pairs and send()s a
bunch of data without recv()ing.
Setup:
# mkdir /sys/fs/cgroup/test
# echo $$ >> /sys/fs/cgroup/test/cgroup.procs
# sysctl -q net.ipv4.tcp_mem="1000 1000 1000"
# ulimit -n 524288
Without net.core.bypass_prot_mem, charged to tcp_mem & memcg
# python3 pressure.py &
# cat /sys/fs/cgroup/test/memory.stat | grep sock
sock 22642688 <-------------------------------------- charged to memcg
# cat /proc/net/sockstat| grep TCP
TCP: inuse 2006 orphan 0 tw 0 alloc 2008 mem 5376 <-- charged to tcp_mem
# ss -tn | head -n 5
State Recv-Q Send-Q Local Address:Port Peer Address:Port
ESTAB 2000 0 127.0.0.1:34479 127.0.0.1:53188
ESTAB 2000 0 127.0.0.1:34479 127.0.0.1:49972
ESTAB 2000 0 127.0.0.1:34479 127.0.0.1:53868
ESTAB 2000 0 127.0.0.1:34479 127.0.0.1:53554
# nstat | grep Pressure || echo no pressure
TcpExtTCPMemoryPressures 1 0.0
With net.core.bypass_prot_mem=1, charged to memcg only:
# sysctl -q net.core.bypass_prot_mem=1
# python3 pressure.py &
# cat /sys/fs/cgroup/test/memory.stat | grep sock
sock 2757468160 <------------------------------------ charged to memcg
# cat /proc/net/sockstat | grep TCP
TCP: inuse 2006 orphan 0 tw 0 alloc 2008 mem 0 <- NOT charged to tcp_mem
# ss -tn | head -n 5
State Recv-Q Send-Q Local Address:Port Peer Address:Port
ESTAB 111000 0 127.0.0.1:36019 127.0.0.1:49026
ESTAB 110000 0 127.0.0.1:36019 127.0.0.1:45630
ESTAB 110000 0 127.0.0.1:36019 127.0.0.1:44870
ESTAB 111000 0 127.0.0.1:36019 127.0.0.1:45274
# nstat | grep Pressure || echo no pressure
no pressure
Signed-off-by: Kuniyuki Iwashima <kuniyu@google.com>
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Link: https://patch.msgid.link/20251014235604.3057003-4-kuniyu@google.com
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Add a new sysctl to control how often a queue reselection
can happen even if a flow has a persistent queue of skbs
in a Qdisc or NIC queue.
A value of zero means the feature is disabled.
Default is 1000 (1 second).
This sysctl is used in the following patch.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Kuniyuki Iwashima <kuniyu@google.com>
Link: https://patch.msgid.link/20251013152234.842065-4-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Pull documentation updates from Jonathan Corbet:
"It has been a relatively busy cycle in docsland, with changes all
over:
- Bring the kernel memory-model docs into the Sphinx build in the
"literal include" mode.
- Lots of build-infrastructure work, further cleaning up long-term
kernel-doc technical debt. The sphinx-pre-install tool has been
converted to Python and updated for current systems.
- A new tool to detect when documents have been moved and generate
HTML redirects; this can be used on kernel.org (or any other site
hosting the rendered docs) to avoid breaking links.
- Automated processing of the YAML files describing the netlink
protocol.
- A significant update of the maintainer's PGP guide.
... and a seemingly endless series of typo fixes, build-problem fixes,
etc"
* tag 'docs-6.18' of git://git.lwn.net/linux: (193 commits)
Documentation/features: Update feature lists for 6.17-rc7
docs: remove cdomain.py
Documentation/process: submitting-patches: fix typo in "were do"
docs: dev-tools/lkmm: Fix typo of missing file extension
Documentation: trace: histogram: Convert ftrace docs cross-reference
Documentation: trace: histogram-design: Wrap introductory note in note:: directive
Documentation: trace: historgram-design: Separate sched_waking histogram section heading and the following diagram
Documentation: trace: histogram-design: Trim trailing vertices in diagram explanation text
Documentation: trace: histogram: Fix histogram trigger subsection number order
docs: driver-api: fix spelling of "buses".
Documentation: fbcon: Use admonition directives
Documentation: fbcon: Reindent 8th step of attach/detach/unload
Documentation: fbcon: Add boot options and attach/detach/unload section headings
docs: filesystems: sysfs: add remaining top level sysfs directory descriptions
docs: filesystems: sysfs: clarify symlink destinations in dev and bus/devices descriptions
docs: filesystems: sysfs: remove top level sysfs net directory
docs: maintainer: Fix ambiguous subheading formatting
docs: kdoc: a few more dump_typedef() tweaks
docs: kdoc: remove redundant comment stripping in dump_typedef()
docs: kdoc: remove some dead code in dump_typedef()
...
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull non-MM updates from Andrew Morton:
- "ida: Remove the ida_simple_xxx() API" from Christophe Jaillet
completes the removal of this legacy IDR API
- "panic: introduce panic status function family" from Jinchao Wang
provides a number of cleanups to the panic code and its various
helpers, which were rather ad-hoc and scattered all over the place
- "tools/delaytop: implement real-time keyboard interaction support"
from Fan Yu adds a few nice user-facing usability changes to the
delaytop monitoring tool
- "efi: Fix EFI boot with kexec handover (KHO)" from Evangelos
Petrongonas fixes a panic which was happening with the combination of
EFI and KHO
- "Squashfs: performance improvement and a sanity check" from Phillip
Lougher teaches squashfs's lseek() about SEEK_DATA/SEEK_HOLE. A mere
150x speedup was measured for a well-chosen microbenchmark
- plus another 50-odd singleton patches all over the place
* tag 'mm-nonmm-stable-2025-10-02-15-29' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (75 commits)
Squashfs: reject negative file sizes in squashfs_read_inode()
kallsyms: use kmalloc_array() instead of kmalloc()
MAINTAINERS: update Sibi Sankar's email address
Squashfs: add SEEK_DATA/SEEK_HOLE support
Squashfs: add additional inode sanity checking
lib/genalloc: fix device leak in of_gen_pool_get()
panic: remove CONFIG_PANIC_ON_OOPS_VALUE
ocfs2: fix double free in user_cluster_connect()
checkpatch: suppress strscpy warnings for userspace tools
cramfs: fix incorrect physical page address calculation
kernel: prevent prctl(PR_SET_PDEATHSIG) from racing with parent process exit
Squashfs: fix uninit-value in squashfs_get_parent
kho: only fill kimage if KHO is finalized
ocfs2: avoid extra calls to strlen() after ocfs2_sprintf_system_inode_name()
kernel/sys.c: fix the racy usage of task_lock(tsk->group_leader) in sys_prlimit64() paths
sched/task.h: fix the wrong comment on task_lock() nesting with tasklist_lock
coccinelle: platform_no_drv_owner: handle also built-in drivers
coccinelle: of_table: handle SPI device ID tables
lib/decompress: use designated initializers for struct compress_format
efi: support booting with kexec handover (KHO)
...
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User reported current document about SYS_INFO_PANIC_CONSOLE_REPLAY is
confusing, that people could expect all user space console messages to be
replayed.
Specify that only 'kernel' messages will be replayed to solve the confusion.
Link: https://lkml.kernel.org/r/20250825025701.81921-3-feng.tang@linux.alibaba.com
Signed-off-by: Feng Tang <feng.tang@linux.alibaba.com>
Reported-by: Askar Safin <safinaskar@zohomail.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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Add a few missing directories under /proc/sys.
Fix punctuation and doubled words.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: linux-doc@vger.kernel.org
Reviewed-by: Rik van Riel <riel@surriel.com>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20250819075456.113623-1-rdunlap@infradead.org
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SO_RCVBUF and SO_SNDBUF have limited range today, unless
distros or system admins change rmem_max and wmem_max.
Even iproute2 uses 1 MB SO_RCVBUF which is capped by
the kernel.
Decouple [rw]mem_max and [rw]mem_default and increase
[rw]mem_max to 4 MB.
Before:
$ sysctl net.core.rmem_default net.core.rmem_max net.core.wmem_default net.core.wmem_max
net.core.rmem_default = 212992
net.core.rmem_max = 212992
net.core.wmem_default = 212992
net.core.wmem_max = 212992
After:
$ sysctl net.core.rmem_default net.core.rmem_max net.core.wmem_default net.core.wmem_max
net.core.rmem_default = 212992
net.core.rmem_max = 4194304
net.core.wmem_default = 212992
net.core.wmem_max = 4194304
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Link: https://patch.msgid.link/20250819174030.1986278-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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The pipe size limit used when the fs.pipe-user-pages-soft sysctl value
is reached was increased from one to two pages in commit 46c4c9d1beb7;
update the documentation to match the new reality.
Fixes: 46c4c9d1beb7 ("pipe: increase minimum default pipe size to 2 pages")
Signed-off-by: Štěpán Němec <stepnem@smrk.net>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20250729-pipedoc-v2-1-18b8e735a9c6@smrk.net
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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
...
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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()
...
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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
...
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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>
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Removing them solves an issue where they were incorrectly considered as
not implemented by the check-sysctl-docs script
Signed-off-by: Joel Granados <joel.granados@kernel.org>
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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>
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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>
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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>
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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
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In commit b5325b2a270f ("coredump: hand a pidfd to the usermode coredump
helper") a new core_pattern specifier, %F, was added to provide a pidfs
to the usermode helper process referring to the crashed process.
Update the documentation to include the new core_pattern specifier.
Signed-off-by: Salvatore Bonaccorso <carnil@debian.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/20250612060204.1159734-1-carnil@debian.org
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- "Add folio_mk_pte()" from Matthew Wilcox simplifies the act of
creating a pte which addresses the first page in a folio and reduces
the amount of plumbing which architecture must implement to provide
this.
- "Misc folio patches for 6.16" from Matthew Wilcox is a shower of
largely unrelated folio infrastructure changes which clean things up
and better prepare us for future work.
- "memory,x86,acpi: hotplug memory alignment advisement" from Gregory
Price adds early-init code to prevent x86 from leaving physical
memory unused when physical address regions are not aligned to memory
block size.
- "mm/compaction: allow more aggressive proactive compaction" from
Michal Clapinski provides some tuning of the (sadly, hard-coded (more
sadly, not auto-tuned)) thresholds for our invokation of proactive
compaction. In a simple test case, the reduction of a guest VM's
memory consumption was dramatic.
- "Minor cleanups and improvements to swap freeing code" from Kemeng
Shi provides some code cleaups and a small efficiency improvement to
this part of our swap handling code.
- "ptrace: introduce PTRACE_SET_SYSCALL_INFO API" from Dmitry Levin
adds the ability for a ptracer to modify syscalls arguments. At this
time we can alter only "system call information that are used by
strace system call tampering, namely, syscall number, syscall
arguments, and syscall return value.
This series should have been incorporated into mm.git's "non-MM"
branch, but I goofed.
- "fs/proc: extend the PAGEMAP_SCAN ioctl to report guard regions" from
Andrei Vagin extends the info returned by the PAGEMAP_SCAN ioctl
against /proc/pid/pagemap. This permits CRIU to more efficiently get
at the info about guard regions.
- "Fix parameter passed to page_mapcount_is_type()" from Gavin Shan
implements that fix. No runtime effect is expected because
validate_page_before_insert() happens to fix up this error.
- "kernel/events/uprobes: uprobe_write_opcode() rewrite" from David
Hildenbrand basically brings uprobe text poking into the current
decade. Remove a bunch of hand-rolled implementation in favor of
using more current facilities.
- "mm/ptdump: Drop assumption that pxd_val() is u64" from Anshuman
Khandual provides enhancements and generalizations to the pte dumping
code. This might be needed when 128-bit Page Table Descriptors are
enabled for ARM.
- "Always call constructor for kernel page tables" from Kevin Brodsky
ensures that the ctor/dtor is always called for kernel pgtables, as
it already is for user pgtables.
This permits the addition of more functionality such as "insert hooks
to protect page tables". This change does result in various
architectures performing unnecesary work, but this is fixed up where
it is anticipated to occur.
- "Rust support for mm_struct, vm_area_struct, and mmap" from Alice
Ryhl adds plumbing to permit Rust access to core MM structures.
- "fix incorrectly disallowed anonymous VMA merges" from Lorenzo
Stoakes takes advantage of some VMA merging opportunities which we've
been missing for 15 years.
- "mm/madvise: batch tlb flushes for MADV_DONTNEED and MADV_FREE" from
SeongJae Park optimizes process_madvise()'s TLB flushing.
Instead of flushing each address range in the provided iovec, we
batch the flushing across all the iovec entries. The syscall's cost
was approximately halved with a microbenchmark which was designed to
load this particular operation.
- "Track node vacancy to reduce worst case allocation counts" from
Sidhartha Kumar makes the maple tree smarter about its node
preallocation.
stress-ng mmap performance increased by single-digit percentages and
the amount of unnecessarily preallocated memory was dramaticelly
reduced.
- "mm/gup: Minor fix, cleanup and improvements" from Baoquan He removes
a few unnecessary things which Baoquan noted when reading the code.
- ""Enhance sysfs handling for memory hotplug in weighted interleave"
from Rakie Kim "enhances the weighted interleave policy in the memory
management subsystem by improving sysfs handling, fixing memory
leaks, and introducing dynamic sysfs updates for memory hotplug
support". Fixes things on error paths which we are unlikely to hit.
- "mm/damon: auto-tune DAMOS for NUMA setups including tiered memory"
from SeongJae Park introduces new DAMOS quota goal metrics which
eliminate the manual tuning which is required when utilizing DAMON
for memory tiering.
- "mm/vmalloc.c: code cleanup and improvements" from Baoquan He
provides cleanups and small efficiency improvements which Baoquan
found via code inspection.
- "vmscan: enforce mems_effective during demotion" from Gregory Price
changes reclaim to respect cpuset.mems_effective during demotion when
possible. because presently, reclaim explicitly ignores
cpuset.mems_effective when demoting, which may cause the cpuset
settings to violated.
This is useful for isolating workloads on a multi-tenant system from
certain classes of memory more consistently.
- "Clean up split_huge_pmd_locked() and remove unnecessary folio
pointers" from Gavin Guo provides minor cleanups and efficiency gains
in in the huge page splitting and migrating code.
- "Use kmem_cache for memcg alloc" from Huan Yang creates a slab cache
for `struct mem_cgroup', yielding improved memory utilization.
- "add max arg to swappiness in memory.reclaim and lru_gen" from
Zhongkun He adds a new "max" argument to the "swappiness=" argument
for memory.reclaim MGLRU's lru_gen.
This directs proactive reclaim to reclaim from only anon folios
rather than file-backed folios.
- "kexec: introduce Kexec HandOver (KHO)" from Mike Rapoport is the
first step on the path to permitting the kernel to maintain existing
VMs while replacing the host kernel via file-based kexec. At this
time only memblock's reserve_mem is preserved.
- "mm: Introduce for_each_valid_pfn()" from David Woodhouse provides
and uses a smarter way of looping over a pfn range. By skipping
ranges of invalid pfns.
- "sched/numa: Skip VMA scanning on memory pinned to one NUMA node via
cpuset.mems" from Libo Chen removes a lot of pointless VMA scanning
when a task is pinned a single NUMA mode.
Dramatic performance benefits were seen in some real world cases.
- "JFS: Implement migrate_folio for jfs_metapage_aops" from Shivank
Garg addresses a warning which occurs during memory compaction when
using JFS.
- "move all VMA allocation, freeing and duplication logic to mm" from
Lorenzo Stoakes moves some VMA code from kernel/fork.c into the more
appropriate mm/vma.c.
- "mm, swap: clean up swap cache mapping helper" from Kairui Song
provides code consolidation and cleanups related to the folio_index()
function.
- "mm/gup: Cleanup memfd_pin_folios()" from Vishal Moola does that.
- "memcg: Fix test_memcg_min/low test failures" from Waiman Long
addresses some bogus failures which are being reported by the
test_memcontrol selftest.
- "eliminate mmap() retry merge, add .mmap_prepare hook" from Lorenzo
Stoakes commences the deprecation of file_operations.mmap() in favor
of the new file_operations.mmap_prepare().
The latter is more restrictive and prevents drivers from messing with
things in ways which, amongst other problems, may defeat VMA merging.
- "memcg: decouple memcg and objcg stocks"" from Shakeel Butt decouples
the per-cpu memcg charge cache from the objcg's one.
This is a step along the way to making memcg and objcg charging
NMI-safe, which is a BPF requirement.
- "mm/damon: minor fixups and improvements for code, tests, and
documents" from SeongJae Park is yet another batch of miscellaneous
DAMON changes. Fix and improve minor problems in code, tests and
documents.
- "memcg: make memcg stats irq safe" from Shakeel Butt converts memcg
stats to be irq safe. Another step along the way to making memcg
charging and stats updates NMI-safe, a BPF requirement.
- "Let unmap_hugepage_range() and several related functions take folio
instead of page" from Fan Ni provides folio conversions in the
hugetlb code.
* tag 'mm-stable-2025-05-31-14-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (285 commits)
mm: pcp: increase pcp->free_count threshold to trigger free_high
mm/hugetlb: convert use of struct page to folio in __unmap_hugepage_range()
mm/hugetlb: refactor __unmap_hugepage_range() to take folio instead of page
mm/hugetlb: refactor unmap_hugepage_range() to take folio instead of page
mm/hugetlb: pass folio instead of page to unmap_ref_private()
memcg: objcg stock trylock without irq disabling
memcg: no stock lock for cpu hot-unplug
memcg: make __mod_memcg_lruvec_state re-entrant safe against irqs
memcg: make count_memcg_events re-entrant safe against irqs
memcg: make mod_memcg_state re-entrant safe against irqs
memcg: move preempt disable to callers of memcg_rstat_updated
memcg: memcg_rstat_updated re-entrant safe against irqs
mm: khugepaged: decouple SHMEM and file folios' collapse
selftests/eventfd: correct test name and improve messages
alloc_tag: check mem_profiling_support in alloc_tag_init
Docs/damon: update titles and brief introductions to explain DAMOS
selftests/damon/_damon_sysfs: read tried regions directories in order
mm/damon/tests/core-kunit: add a test for damos_set_filters_default_reject()
mm/damon/paddr: remove unused variable, folio_list, in damon_pa_stat()
mm/damon/sysfs-schemes: fix wrong comment on damons_sysfs_quota_goal_metric_strs
...
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On our HDFS servers with 12 HDDs per server, a HDFS datanode[0] startup
involves scanning all files and caching their metadata (including dentries
and inodes) in memory. Each HDD contains approximately 2 million files,
resulting in a total of ~20 million cached dentries after initialization.
To minimize dentry reclamation, we set vfs_cache_pressure to 1. Despite
this configuration, memory pressure conditions can still trigger
reclamation of up to 50% of cached dentries, reducing the cache from 20
million to approximately 10 million entries. During the subsequent cache
rebuild period, any HDFS datanode restart operation incurs substantial
latency penalties until full cache recovery completes.
To maintain service stability, we need to preserve more dentries during
memory reclamation. The current minimum reclaim ratio (1/100 of total
dentries) remains too aggressive for our workload. This patch introduces
vfs_cache_pressure_denom for more granular cache pressure control. The
configuration [vfs_cache_pressure=1, vfs_cache_pressure_denom=10000]
effectively maintains the full 20 million dentry cache under memory
pressure, preventing datanode restart performance degradation.
Link: https://hadoop.apache.org/docs/r1.2.1/hdfs_design.html#NameNode+and+DataNodes [0]
Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/20250511083624.9305-1-laoar.shao@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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