wq_node_nr_active() warns and returns NULL when @wq is not unbound, but
every caller dereferences the result right away, so the WARN_ON_ONCE()
only moves the oops one frame up, as raised by Tejun.
Fix it by BUGing_ON() instead of this silly WARN_ON_ONCE();
Fixes: b72fdc6510 ("workqueue: account nr_active by the backing pool")
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
wq->cpu_pwq holds RCU-protected pwq pointers, but the percpu allocation
path fills it in with plain loads and stores, which sparse flags:
kernel/workqueue.c:5682:57: sparse: incorrect type in initializer (different address spaces) @@ expected struct pool_workqueue **pwq_p @@ got struct pool_workqueue [noderef] __rcu ** @@
Allocate the array as __rcu pointers and publish each pwq with
rcu_assign_pointer() once it is initialized and linked, the order
install_unbound_pwq() uses.
The warnings are not new: commit 79f23600bc ("workqueue: factor out
get_percpu_pool()") only turned the flagged assignment into an
initializer.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202608120931.tvTzq1gD-lkp@intel.com/
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
workqueue_congested() fetches the pwq out of wq->cpu_pwq with a plain
load, so sparse complains about the dropped __rcu:
kernel/workqueue.c:6304:13: sparse: incorrect type in assignment (different address spaces) @@ expected struct pool_workqueue *pwq @@ got struct pool_workqueue [noderef] __rcu * @@
A pwq is released with kfree_rcu() and the read is protected by the
surrounding preempt_disable(), which is what
commit fd5081f4ef ("workqueue: Remove redundant rcu_read_lock/unlock() in
workqueue_congested()") relied on when it dropped the rcu_read_lock()
here.
Use the rcu_dereference_sched() helper to make that explicit.
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202608120931.tvTzq1gD-lkp@intel.com/
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
apply_wqattrs_commit() updates node_nr_active->max unconditionally.
wq->node_nr_active[] is only allocated for unbound workqueues, so guard
the call before per-cpu workqueues start using this path.
No functional change: only unbound workqueues reach apply_wqattrs_*()
today.
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
This allocates a pwq and binds it to the pool @attrs asks for.
Which pool that is becomes a property of the attrs (once per-cpu becomes
an affinity scope).
Remove the 'unbound" from the function name, given it will be bigger
than unbound.
No functional change.
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
The attrs are where the affinity scope lives, and a per-cpu workqueue
will need one once per-cpu becomes a scope rather than a separate
backend. Allocate them unconditionally.
wq_dump.py used a non-NULL wq->attrs as its test for an unbound
workqueue, which no longer holds; test WQ_UNBOUND there instead.
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
The unbound prefix says which workqueues currently have the field rather
than what it holds, and the next patch allocates it for every workqueue.
Rename it first so that change stays a single line.
tools/workqueue/wq_dump.py reads the field by name, so rename it there
too.
wq_sysfs_unbound_attrs[] keeps its name: it is the set of sysfs files
that only unbound workqueues expose.
No functional change.
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
workqueue_online_cpu() and workqueue_offline_cpu() decide whether a
workqueue needs a pod affinity update by testing wq->unbound_attrs for
NULL, which is only meaningful because the attrs are allocated for
unbound workqueues alone.
Test the flag instead, so the attrs can later be allocated for every
workqueue.
No functional change.
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
pwq_tryinc_nr_active() and pwq_dec_nr_active() choose between the shared
per-node nr_active and the plain per-pwq one by testing
wq_node_nr_active() for NULL.
Test the backing pool with is_percpu_pool() instead, so the accounting
follows the pool that runs the work rather than the workqueue type.
No functional change.
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Add is_percpu_pool() and test the pool directly for per cpu. Convert the
other open-coded pool->cpu checks -- in put_unbound_pool(),
pool_allowed_cpus() and the workqueue watchdog -- to the same helper.
No functional change.
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Move the per-cpu pwq allocation loop out of alloc_and_link_pwqs() into a
helper. The inner allocation-failure path now returns -ENOMEM and the
caller jumps to the existing enomem cleanup, equivalent to the previous
goto.
No functional change.
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Move the static per-cpu worker_pool lookup in alloc_and_link_pwqs() into
a helper, get_percpu_pool(), so the lookup can be shared by other
pool-selection paths.
No functional change.
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
The automatic CPU-intensive work item detection reads the worker task's
se.sum_exec_runtime without a lock in wq_worker_running(),
wq_worker_tick() and process_one_work(). The scheduler updates that
field under the rq lock (from the tick via update_curr(), or cross-CPU
via task_sched_runtime()), raising:
BUG: KCSAN: data-race in wq_worker_running+0xa8/0xe8
race at unknown origin, with read to 0xffff0009a11d1df8 of 8 bytes by task 238535 on cpu 68:
wq_worker_running
schedule
schedule_preempt_disabled
__mutex_lock
mutex_lock_nested
cgroup_bpf_release
process_one_work
worker_thread
kthread
ret_from_fork
value changed: 0x0000000088482ba0 -> 0x00000000884893c0
The value only feeds a heuristic, so the race is benign-ish. Unlike
commit ecf5aad9a4 ("workqueue: annotate racy PWQ_STAT_CPU_TIME update
in wq_worker_tick()") that only needs data_race(), these are plain reads
whose result drives a subtraction and comparison, so use READ_ONCE() for
a single, non-torn load, which also silences KCSAN.
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
wq_worker_tick() bumps pwq->stats[PWQ_STAT_CPU_TIME] on every scheduler
tick before pool->lock is taken. For unbound workqueues the
pool_workqueue is shared by all workers of the pool across CPUs, so
concurrent ticks on different CPUs perform an unsynchronized 64-bit
read-modify-write on the same counter. KCSAN reports this as a
data-race:
BUG: KCSAN: data-race in wq_worker_tick / wq_worker_tick
read-write to 0xffff0004d6989500 of 8 bytes by interrupt on cpu 29:
wq_worker_tick+0x70/0x418
sched_tick+0x248/0x3a0
update_process_times+0x200/0x260
tick_nohz_handler+0x230/0x2f8
__hrtimer_run_queues+0x1ec/0x6c8
hrtimer_interrupt+0x174/0x4b8
...
read-write to 0xffff0004d6989500 of 8 bytes by interrupt on cpu 24:
wq_worker_tick+0x70/0x418
sched_tick+0x248/0x3a0
...
value changed: 0x000000000010a1d0 -> 0x000000000010a9a0
The counter is purely advisory, so an occasional lost update is
harmless, and every other stats[] update already runs under pool->lock.
Annotate the update with data_race().
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
To identify the task most likely responsible for a stall, add
last_woken_worker (L: pool->lock) to worker_pool and record it in
kick_pool() just before wake_up_process(). This captures the idle
worker that was kicked to take over when the last running worker went to
sleep; if the pool is now stuck with no running worker, that task is the
prime suspect and its backtrace is dumped by show_pool_no_running_worker().
Using struct worker * rather than struct task_struct * avoids any
lifetime concern: workers are only destroyed via set_worker_dying()
which requires pool->lock, and set_worker_dying() clears
last_woken_worker when the dying worker matches.
show_cpu_pool_busy_workers() holds pool->lock while calling
sched_show_task(), so last_woken_worker is either NULL or points to a
live worker with a valid task. More precisely, set_worker_dying() clears
last_woken_worker before setting WORKER_DIE, so a non-NULL
last_woken_worker means the kthread has not yet exited and worker->task
is still alive.
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
When a CPU pool is stalled with no running worker, the task occupying the
CPU may not be a workqueue worker at all. Trigger a single-CPU backtrace
for the stalled CPU to capture what it is currently executing.
The CPU is snapshotted under pool->lock and the backtrace is triggered
after releasing the lock to avoid any potential issues with NMI delivery.
Skip the backtrace when the CPU is offline. A pool disassociated by CPU
hotplug keeps its pool->cpu, and an NMI to an offline CPU is never acked,
so nmi_trigger_cpumask_backtrace() would busy-wait for its full timeout
in the watchdog's timer context.
Suggested-by: Petr Mladek <pmladek@suse.com>
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
show_cpu_pool_busy_workers() dumps every in-flight worker in the pool's
busy_hash, including workers that are not currently running on the CPU.
Restore the task_is_running() filter so only running workers are dumped.
When no running worker is found the pool may be stuck, unable to wake an
idle worker to process pending work, and the watchdog would otherwise
give no feedback. Add show_pool_no_running_worker() to report the pool
id, CPU, idle state, and worker counts in that case.
The pool info message is printed inside pool->lock using
printk_deferred_enter/exit, the same pattern used by the existing
busy-worker loop, to avoid deadlocks with console drivers that queue
work while holding locks also taken in their write paths.
This has been running on the Meta fleet for a while and caught some real
issues, for instance EFI stalls stalling the workqueue [1].
Link: https://lore.kernel.org/all/20260616-efi_timeout-v3-0-76dd1d26657b@debian.org/ [1]
Suggested-by: Petr Mladek <pmladek@suse.com>
Fixes: 8823eaef45 ("workqueue: Show all busy workers in stall diagnostics")
Reviewed-by: Petr Mladek <pmladek@suse.com>
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Use kick_pool_pick() to select and claim the worker under pool->lock and
issue the wakeup with wake_up_process() after the lock is dropped.
Unlike __queue_work(), this path has no surrounding RCU section, so take
rcu_read_lock() before dropping pool->lock to keep the picked worker's
task_struct valid across the wakeup.
Signed-off-by: Breno Leitao <leitao@debian.org>
Tested-by: Krishna Magar <kmagar@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
__queue_work() is the enqueue hot path: it inserts the work item and
calls kick_pool() while holding pool->lock. kick_pool() ends in a
wakeup, which takes the target task's rq->lock, so rq->lock nests under
pool->lock on every enqueue that wakes a worker on a contended unbound
pool.
Use kick_pool_pick() to select and claim the worker under pool->lock and
issue the wakeup with wake_up_process() right after dropping the lock.
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Factor the worker selection out of kick_pool() into kick_pool_pick(),
which picks and claims the worker under pool->lock but, instead of waking
it, returns the worker's task via an out-param so the caller can issue
the wakeup after dropping pool->lock. BH kicks and wake_cpu setup still
happen under the lock.
kick_pool() becomes a thin wrapper that wakes the returned task, so all
existing callers keep waking under pool->lock.
Pure refactor, no functional change.
Signed-off-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Pull misc timer fixes from Ingo Molnar:
- Fix timekeeping locking order bug in the timekeeping init code
(Mikhail Gavrilov)
- Fix u64 multiplication bug in the posix-cpu-timers code on 32-bit
kernels (Zhan Xusheng)
- Fix macro name in comment block (Ethan Nelson-Moore)
- Fix off-by-one bug in the compat settimeofday() usecs validation code
(Wang Yan)
* tag 'timers-urgent-2026-06-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
time: Fix off-by-one in compat settimeofday() usec validation
hrtimer: Correct CONFIG_NO_HZ_COMMON macro name in comment
posix-cpu-timers: Use u64 multiplication in update_rlimit_cpu()
timekeeping: Register default clocksource before taking tk_core.lock
Pull misc CPU hotplug fixes from Ingo Molnar:
- Fix CPU hotplug error handling rollback bug (Bradley Morgan)
- Fix possible output OOB write bug in the sysfs hotplug states
printing code (Bradley Morgan)
* tag 'smp-urgent-2026-06-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
cpu: hotplug: Bound hotplug states sysfs output
cpu: hotplug: Preserve per instance callback errors
Pull locking fix from Ingo Molnar:
- Fix the incorrect RCU protection in rt_spin_unlock() (Thomas
Gleixner)
* tag 'locking-urgent-2026-06-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
locking/rt: Fix the incorrect RCU protection in rt_spin_unlock()
Pull misc core fixes from Ingo Molnar:
- Fix an MM-CID race that can cause an OOB write (Rik van Riel)
- Fix a debugobjects OOM handling race (Thomas Gleixner)
* tag 'core-urgent-2026-06-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
debugobjects: Plug race against a concurrent OOM disable
sched/mmcid: Fix OOB clear_bit when CID is MM_CID_UNSET in fixup path
Pull sched_ext tree reorg from Tejun Heo:
"Pure source reorganization with no functional change:
- the kernel/sched/ext* files move into a new kernel/sched/ext/
subdirectory
- the headers and sources are made self-contained so editor tooling
can parse each file on its own"
* tag 'sched_ext-for-7.2-1' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
sched_ext: Move shared helpers from ext.c into internal.h and cid.h
sched_ext: Make kernel/sched/ext/ sources self-contained for clangd
sched_ext: Move sources under kernel/sched/ext/
idle.c and cid.c are included into build_policy.c together with ext.c and
use helpers that ext.c defines. Because the helpers live in ext.c, the two
files can not parse as standalone units and clangd reports errors in them.
Move the helpers to the headers they belong to. The op-dispatch macros and
helpers plus scx_parent() to internal.h, and scx_cpu_arg()/scx_cpu_ret() to
cid.h. No functional change. idle.c and cid.c now parse clean standalone.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
The sources under kernel/sched/ext/ build as a single translation unit:
build_policy.c includes the source files and headers. An LSP/clangd editor
parses each as a standalone unit, sees no types, and reports a flood of
errors.
Give each header its dependencies and include guard, and have each source
include the headers it uses.
ext.c, arena.c and the ext headers now parse clean standalone. idle.c and
cid.c still reference a few macros and helpers defined in ext.c. The next
patch moves those to shared headers.
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
The sched_ext sources had grown to ten ext* files directly under
kernel/sched/. Move them into a new kernel/sched/ext/ subdirectory and drop
the now-redundant ext_ prefix. ext.c/h keep their names.
kernel/sched/ext.{c,h} -> kernel/sched/ext/ext.{c,h}
kernel/sched/ext_internal.h -> kernel/sched/ext/internal.h
kernel/sched/ext_types.h -> kernel/sched/ext/types.h
kernel/sched/ext_idle.{c,h} -> kernel/sched/ext/idle.{c,h}
kernel/sched/ext_cid.{c,h} -> kernel/sched/ext/cid.{c,h}
kernel/sched/ext_arena.{c,h} -> kernel/sched/ext/arena.{c,h}
The include paths in build_policy.c and sched.h, the MAINTAINERS glob, and a
few documentation and comment references are updated to match. No code or
symbol changes.
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Reviewed-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Pull more s390 updates from Alexander Gordeev:
- consolidate s390 idle time accounting by moving all CPU time tracking
to the architecture backend and eliminate the mix of architecture-
specific and common code accounting
- Add missing EXPORT_SYMBOL_GPL() to kcpustat_field_idle() and
kcpustat_field_iowait() functions
- Finalize ptep_get() conversion by replacing direct page table entry
dereferencing with proper accessors (ptep_get(), pmdp_get(), etc.)
- Explicitly check the buffer length in PKEY_VERIFYPROTK ioctl and
pkey_pckmo implementations and fail if the length is exceeded
* tag 's390-7.2-2' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
s390/pkey: Check length in pkey_pckmo handler implementation
s390/pkey: Check length in PKEY_VERIFYPROTK ioctl
s390/idle: Add missing EXPORT_SYMBOL_GPL()
s390/mm: Complete ptep_get() conversion
s390/idle: Remove idle time and count sysfs files
s390/idle: Provide arch specific kcpustat_field_idle()/kcpustat_field_iowait()
s390/irq/idle: Use stcke instead of stckf for time stamps
s390/timex: Move union tod_clock type to separate header
The compat version of settimeofday() uses '>' instead of '>=' when
validating tv_usec against USEC_PER_SEC, allowing the value 1000000 to pass
the check. After the subsequent conversion to nanoseconds (tv_nsec *=
NSEC_PER_USEC), this results in tv_nsec == NSEC_PER_SEC, which violates the
timespec invariant that tv_nsec must be strictly less than NSEC_PER_SEC.
The native settimeofday() was already fixed in commit ce4abda5e1 ("time:
Fix off-by-one in settimeofday() usec validation"), but the compat
counterpart was missed.
Fix it by using '>=' to reject tv_usec values outside the valid range [0,
USEC_PER_SEC - 1].
Fixes: 5e0fb1b57b ("y2038: time: avoid timespec usage in settimeofday()")
Signed-off-by: Wang Yan <wangyan01@kylinos.cn>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260622103348.120255-1-wangyan01@kylinos.cn
Pull non-MM updates from Andrew Morton:
- "taskstats: fix TGID dead-thread stat retention" (Yiyang Chen)
Fix a taskstats TGID aggregation bug where fields added in the TGID
query path were not preserved after thread exit, and adds a kselftest
covering the regression.
- "lib/tests: string_helpers: Slight improvements" (Andy Shevchenko)
Improve lib/tests/string_helpers_kunit.c a little
- "lib/base64: decode fixes" (Josh Law)
Address minor issues in lib/base64.c
- "selftests/filelock: Make output more kselftestish" (Mark Brown)
Make the output from the ofdlocks test a bit easier for tooling to
work with. Also ignore the generated file
- "uaccess: unify inline vs outline copy_{from,to}_user() selection"
(Yury Norov)
Simplify the usercopy code by removing the selectability of inlining
copy_{from,to}_user().
- "ocfs2: validate inline xattr header consumers" (ZhengYuan Huang)
Fix a number of possible issues in the ocfs2 xattr code
- "lib and lib/cmdline enhancements" (Dmitry Antipov)
Provide additional robustness checking in the cmdline handling code
and its in-kernel testing and selftests
- "cleanup the RAID6 P/Q library" (Christoph Hellwig)
Clean up the RAID6 P/Q library to match the recent updates to the
RAID 5 XOR library and other CRC/crypto libraries
- "ocfs2: harden inode validators against forged metadata" (Michael
Bommarito)
Add three structural checks to OCFS2 dinode validation so malformed
on-disk fields are rejected before ocfs2_populate_inode() copies them
into the in-core inode
- "lib/raid: replace __get_free_pages() call with kmalloc()" (Mike
Rapoport)
Clean up the lib/raid code by using kmalloc() in more places
* tag 'mm-nonmm-stable-2026-06-21-10-22' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (108 commits)
ocfs2: fix circular locking dependency in ocfs2_dio_end_io_write
ocfs2: fix NULL h_transaction deref in ocfs2_assure_trans_credits
lib: interval_tree_test: validate benchmark parameters
ocfs2: avoid moving extents to occupied clusters
treewide: fix transposed "sign" typos and update spelling.txt
ocfs2: fix UBSAN array-index-out-of-bounds in ocfs2_sum_rightmost_rec
fat: reject BPB volumes whose data area starts beyond total sectors
selftests/uevent: increase __UEVENT_BUFFER_SIZE to avoid ENOBUFS on busy systems
lib/test_firmware: allocate the configured into_buf size
fs: efs: remove unneeded debug prints
checkpatch: cuppress warnings when Reported-by: is followed by Link:
MAINTAINERS: add Alexander as a kcov reviewer
mailmap: update Alexander Sverdlin's Email addresses
fs: fat: inode: replace sprintf() with scnprintf()
ocfs2: fix out-of-bounds write in ocfs2_remove_refcount_extent
ocfs2: fix race between ocfs2_control_install_private() and ocfs2_control_release()
ocfs2/dlm: require a ref for locking_state debugfs open
ocfs2: reject FITRIM ranges shorter than a cluster
ocfs2: validate fast symlink target during inode read
ocfs2: add journal NULL check in ocfs2_checkpoint_inode()
...
cpuhp_invoke_callback() unwinds earlier callbacks for the same
hotplug state when one instance fails. The rollback path currently
reuses ret, so a successful rollback can hide the original error and
make the failed transition look successful.
Keep the rollback result separate from the original error.
Fixes: 724a86881d ("smp/hotplug: Callback vs state-machine consistency")
Signed-off-by: Bradley Morgan <include@grrlz.net>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260619163719.12103-1-include@grrlz.net
Pull liveupdate updates from Mike Rapoport:
"Kexec Handover (KHO):
- make memory preservation compatible with deferred initialization
of the memory map
Live Update Orchestrator (LUO):
- add LIVEUPDATE_SESSION_GET_NAME ioctl and parameter verification
for LIVEUPDATE_IOCTL_CREATE_SESSION ioctl
- documentation updates for liveupdate=on command line option,
systemd support and the current compatibility status
- remove the fixed limits on the number of files that can be
preserved within a single session, and the total number of
sessions managed by the LUO
Misc fixes:
- reference count incoming File-Lifecycle-Bound (FLB) data so
it cannot be freed while a subsystem is still using it
- fixes for a TOCTOU race in luo_session_retrieve(), a use-
after-free in the file finish and unpreserve paths, concurrent
session mutations during reboot and serialization on
preserve_context kexec
- make sure ioctls for incoming LUO sessions are blocked for
outgoing sessions and vice versa
- make sure KHO scratch size is always aligned by
CMA_MIN_ALIGNMENT_BYTES
- fix memblock tests build issue introduced by KHO changes"
* tag 'liveupdate-v7.2-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/liveupdate/linux: (36 commits)
liveupdate: Document that retrieve failure is permanent
docs: memfd_preservation: fix rendering of ABI documentation
selftests/liveupdate: Add stress-files kexec test
selftests/liveupdate: Add stress-sessions kexec test
selftests/liveupdate: Test session and file limit removal
liveupdate: Remove limit on the number of files per session
liveupdate: Remove limit on the number of sessions
liveupdate: defer session block allocation and physical address setting
kho: add support for linked-block serialization
liveupdate: Extract luo_session_deserialize_one helper
liveupdate: Extract luo_file_deserialize_one helper
liveupdate: register luo_ser as KHO subtree
liveupdate: centralize state management into struct luo_ser
liveupdate: avoid mixing cleanup guards with goto in luo_session_retrieve_fd
liveupdate: change file_set->count type to u64 for type safety
liveupdate: Remove unused ser field from struct luo_session
liveupdate: fix u-a-f in luo_file_unpreserve_files() and luo_file_finish()
liveupdate: block session mutations during reboot
liveupdate: fix TOCTOU race in luo_session_retrieve()
liveupdate: skip serialization for context-preserving kexec
...
rt_spin_unlock() releases the RCU protection before unlocking the
lock. That opens the door for the following UAF scenario:
T1 T2
spin_lock(&p->lock); rcu_read_lock();
invalidate(p); p = rcu_dereference(ptr);
rcu_assign_pointer(ptr, NULL); if (!p) return;
spin_unlock(&p->lock); spin_lock(&p->lock)
lock(&lock->lock);
rcu_read_lock();
kfree_rcu(p); rcu_read_unlock();
....
spin_unlock(&p->lock)
rcu_read_unlock(); // Ends grace period
rcu_do_batch()
kfree(p);
UAF -> rt_mutex_cmpxchg_release(&lock->lock...)
Regular spinlocks keep preemption disabled accross the unlock operation,
which provides full RCU protection, but the RT substitution fails to
resemble that. Same applies for the rwlock substitution.
Move the rcu_read_unlock() invocation past the unlock operations to match
the non-RT semantics. This makes it asymmetric vs. rt_xxx_lock(), but
that's harmless as the caller needs to hold RCU read lock across the lock
operation. The migrate_enable() call stays before the unlock operation
because there is no per CPU operation in the unlock path which would
require migration to be kept disabled.
Fixes: 0f383b6dc9 ("locking/spinlock: Provide RT variant")
Reported-by: syzbot+000c800a02097aaa10ed@syzkaller.appspotmail.com
Decoded-by: Jann Horn <jannh@google.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/87jyrud75z.ffs@fw13
In mm_cid_fixup_cpus_to_tasks(), when rq->curr has the target mm and
mm_cid.active is set, the CID is checked with cid_in_transit() before
setting the transition bit. In per-CPU mode a newly forked or exec'd
task can be running with mm_cid.cid == MM_CID_UNSET because CIDs are
assigned lazily on schedule-in. With cid_in_transit() the guard passes
for MM_CID_UNSET (no transit bit), converts it to MM_CID_UNSET |
MM_CID_TRANSIT and stores it back; later mm_cid_schedout() feeds this
to clear_bit() with MM_CID_UNSET as the bit number, triggering an
out-of-bounds write.
Symptoms: this is genuine memory corruption, but a bounded out-of-bounds
write, not an arbitrary one. MM_CID_UNSET is the fixed sentinel BIT(31),
so once the bad value reaches mm_cid_schedout() the cid_from_transit_cid()
strip leaves MM_CID_UNSET, which fails the "cid < max_cids" convergence
test and falls into mm_drop_cid() -> clear_bit(MM_CID_UNSET,
mm_cidmask(mm)). The cid bitmap is embedded in the mm_struct slab object
(after cpu_bitmap and mm_cpus_allowed) and is only num_possible_cpus()
bits wide, so clearing bit 31 is a deterministic OOB bit-clear at a
fixed offset of 2^31 / 8 == 256 MiB past the bitmap base. The address is
not attacker-influenced (fixed sentinel -> fixed offset) and the op only
clears a single bit; what sits 256 MiB further along the direct map is
whatever kernel object happens to live there, so this corrupts one bit of
unpredictable kernel memory -- it is not an arbitrary-address or
arbitrary-value write.
It triggers only in per-CPU CID mode, when a CPU is running an active
task of the target mm whose cid is still MM_CID_UNSET -- the
fork()/execve() window before that task's next schedule-in assigns it a
real CID -- and a per-CPU -> per-task fixup walks over it (the mode
fallback driven by a thread exit, sched_mm_cid_exit(), or by the deferred
max_cids recompute in mm_cid_work_fn()).
In practice syzkaller surfaced it as a KASAN use-after-free reported in
__schedule -> mm_cid_switch_to, where the offending clear_bit() is inlined
via mm_cid_schedout() -> mm_drop_cid().
Guard the transition-bit assignment against MM_CID_UNSET, in addition to
the existing cid_in_transit() check, so the bit is only set on a genuine
task-owned CID. A CPU-owned (MM_CID_ONCPU) CID of a running active task
is handled by the cid_on_cpu(pcp->cid) branch above and never reaches
this path, so excluding MM_CID_UNSET (and the already-transitioning case)
is sufficient.
Fixes: fbd0e71dc3 ("sched/mmcid: Provide CID ownership mode fixup functions")
Signed-off-by: Rik van Riel <riel@surriel.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Assisted-by: Claude:claude-opus-4-8 syzkaller
Reviewed-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260616203818.1516263-1-riel@surriel.com
Pull MM updates from Andrew Morton:
- "selftests/mm: clean up build output and verbosity" (Li Wang)
Remove some noise from the MM selftests build
- "mm: Free contiguous order-0 pages efficiently" (Ryan Roberts)
Speed up the freeing of a batch of 0-order pages by first scanning
them for coalescing opportunities. This is applicable to vfree() and
to the releasing of frozen pages
- "mm/damon: introduce DAMOS failed region quota charge ratio"
(SeongJae Park)
Address a DAMOS usability issue: The DAMOS quota often exhausts
prematurely because it charges for all memory attempted, causing slow
and inconsistent performance when actions fail on unreclaimable
memory.
To fix this, a new feature lets users set a smaller, flexible quota
charge ratio (via a numerator and denominator) for failed regions.
Since failed actions cause less overhead, reducing their quota cost
ensures more predictable and efficient DAMOS processing
- "selftests/cgroup: improve zswap tests robustness and support large
page sizes" (Li Wang)
Fix various spurious failures and improves the overall robustness of
the cgroup zswap selftests
- "fix MAP_DROPPABLE not supported errno" (Anthony Yznaga)
Fix an issue in the mlock selftests on arm32
- "mm: huge_memory: clean up defrag sysfs with shared" (Breno Leitao)
Some maintenance work in the huge_memory code
- "treewide: fixup gfp_t printks" (Brendan Jackman)
Use the special vprintf() gfp_t conversion in various places
- "mm: Fix vmemmap optimization accounting and initialization" (Muchun
Song)
Fix several bugs in the vmemmap optimization, mainly around incorrect
page accounting and memmap initialization in the DAX and memory
hotplug paths. It also fixes pageblock migratetype initialization and
struct page initialization for ZONE_DEVICE compound pages
- "mm/damon: repost non-hotfix reviewed patches in damon/next tree"
A sprinkle of unrelated minor bugfixes for DAMON
- "mm: remove page_mapped()" (David Hildenbrand)
Remove this function from the tree, replacing it with folio_mapped()
- "mm/damon: let DAMON be paused and resumed" (SeongJae Park)
Allow DAMON to be paused and resumed without losing its current state
- "kasan: hw_tags: Disable tagging for stack and page-tables" (Muhammad
Usama Anjum)
Simplify and speed up kasan by removing its ineffective tagging of
stacks and page tables
- "mm/damon/reclaim,lru_sort: monitor all system rams by default"
(SeongJae Park)
Simplify deployment on diverse hardware like NUMA systems by updating
DAMON_RECLAIM and DAMON_LRU_SORT to automatically monitor the
physical address range covering all System RAM areas by default,
replacing the overly restrictive behavior that only targeted the
single largest memory block to save on negligible overhead
- "mm/damon/sysfs: document filters/ directory as deprecated" (SeongJae
Park)
Update some DAMON docs
- "mm: use spinlock guards for zone lock" (Dmitry Ilvokhin)
Switch zone->lock handling over to using the guard() mechanisms
- "mm/filemap: tighten mmap_miss hit accounting" (fujunjie)
Fix a flaw where the mmap_miss counter over-credited page cache hits
during fault-arounds and page-fault retries. This results in
significant reduction of redundant synchronous mmap readahead I/O,
drastically cutting down execution time and gigabytes read for sparse
random or strided memory access workloads
- "selftests/cgroup: Fix false positive failures in test_percpu_basic"
(Li Wang)
Fix a couple of false-positives in the cgroup kmem selftests
- "mm/damon/reclaim: support monitoring intervals auto-tuning"
(SeongJae Park)
Add a new parameter to DAMON permitting DAMON_RECLAIM to
automatically tune DAMON's sampling and aggregation intervals
- "mm/damon/stat: add kdamond_pid parameter" (SeongJae Park)
Change DAMON_STAT to provide the pid of its kdamond
- "mm/kmemleak: dedupe verbose scan output" (Breno Leitao)
Remove large amounts of duplicated backtraces from the verbose-mode
kmemleak output
- "mm: remove CONFIG_HAVE_BOOTMEM_INFO_NODE (Part 1)" (David
Hildenbrand)
Reduce our use of CONFIG_HAVE_BOOTMEM_INFO_NODE, with a view to
removing it entirely in a later series
- "mm/damon: validate min_region_size to be power of 2" (Liew Rui Yan)
Prevent users from passing a non-power-of-2 value of `addr_unit', as
this later results in undesirable behavior
- "mm: document read_pages and simplify usage" (Frederick Mayle)
- "tools/mm/page-types: Fix misc bugs" (Ye Liu)
Fix three issues in tools/mm/page-types.c
- "mm: misc cleanups from __GFP_UNMAPPED series" (Brendan Jackman)
Implement several cleanups in the page allocator and related code
- "mm, swap: swap table phase IV: unify allocation" (Kairui Song)
Unify the allocation and charging of anon and shmem swap in folios,
provides better synchronization, consolidates the metadata
management, hence dropping the static array and map, and improves
performance
- "mm/damon: introduce data attributes monitoring" (SeongJae Park(
Extend DAMON to monitor general data attributes other than accesses
- "mm/vmalloc: free unused pages on vrealloc() shrink" (Shivam Kalra)
Implement the TODO in vrealloc() to unmap and free unused pages when
shrinking across a page boundary
- "mm/damon: documentation and comment fixes" (niecheng)
- "remove mmap_action success, error hooks" (Lorenzo Stoakes)
Eliminate custom hooks from mmap_action by removing the problematic
success_hook which allowed drivers to improperly access uninitialized
VMAs. It replaces the error_hook with a simple error-code field and
updates the memory char driver accordingly
- "mm/damon: minor improvements for code readability and tests"
(SeongJae Park)
- "mm/damon: fix macro arguments and clarify quota goals doc" (Maksym
Shcherba)
- "userfaultfd: merge fs/userfaultfd.c into mm/userfaultfd.c" (Mike
Rapoport)
- "mm/mglru: improve reclaim loop and dirty folio" (Kairui Song and
others)
Clean up and slightly improves MGLRU's reclaim loop and dirty
writeback handling. Large performance improvements are measured
- "use vma locks for proc/pid/{smaps|numa_maps} reads" (Suren
Baghdasaryan)
Use per-vma locks when reading /proc/pid/smaps and numa_maps similar
to reduce contention on central mmap_lock
- "refactors thpsize_shmem_enabled_store() and thpsize_shmem_enabled_show()"
(Ran Xiaokai)
Some cleanup work in the THP code
- "selftests/memfd: fix compilation warnings" (Konstantin Khorenko)
Fix a few build glitches in the memfd selftest code.
- "memcg: shrink obj_stock_pcp and cache multiple objcgs" (Shakeel
Butt)
Resolve a 68% performance regression caused by NUMA-node cache
thrashing around struct obj_stock_pcp by shrinking its existing
fields and expanding it into a multi-slot array that caches up to
five obj_cgroup pointers per CPU, allowing per-node variants of the
same memcg to coexist within a single 64-byte cache line.
- "zram: writeback fixes" (Sergey Senozhatsky)
address a couple of unrelated zram writeback issues
- "mm: switch THP shrinker to list_lru" (Johannes Weiner)
Resolve NUMA-awareness issues and streamlines callsite interaction by
refactoring and extending the list_lru API to completely replace the
complex, open-coded deferred split queue for Transparent Huge Pages
- "mm: improve large folio readahead for exec memory" (Usama Arif)
Improve large-folio readahead on systems like 64K-page arm64 by
preventing the mmap_miss check from permanently disabling
target-oriented VM_EXEC readahead, and by generalizing the
force_thp_readahead gate to support mappings with any usefully large
maximum folio order under the cache cap.
- "userfaultfd/pagemap: pre-existing fixes" (Kiryl Shutsemau)
Fix a bunch of minor issues in the userfaultfd/pagemap, all of which
were flagged by Sashiko review of proposed new material
- "mm/sparse-vmemmap: Provide generic vmemmap_set_pmd() and
vmemmap_check_pmd()" (Muchun Song)
Provide generic versions of these two functions so the four
arch-specific implementations can be removed.
- "mm/swap, PM: hibernate: fix swapoff race in uswsusp by pinning swap
device" (Youngjun Park)
Address a uswsusp-vs-swapoff race and reduces the swap device
reference taking/releasing frequency.
- "mm/hmm: A fix and a selftest" (Dev Jain)
* tag 'mm-stable-2026-06-18-09-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (321 commits)
selftests/mm/hmm-tests: test pagemap reads of PMD device-private entries
fs/proc/task_mmu: do not warn on seeing non-migration pmd entry
lib/test_hmm: check alloc_page_vma() return value and handle OOM
mm/compaction: cap compact_gap() at COMPACT_CLUSTER_MAX
mm/swap: remove redundant swap device reference in alloc/free
mm/swap, PM: hibernate: fix swapoff race in uswsusp by pinning swap device
mm/filemap: use folio_next_index() for start
vmalloc: fix NULL pointer dereference in is_vm_area_hugepages()
sparc/mm: drop vmemmap_check_pmd helper and use generic code
loongarch/mm: drop vmemmap_check_pmd helper and use generic code
riscv/mm: drop vmemmap_pmd helpers and use generic code
arm64/mm: drop vmemmap_pmd helpers and use generic code
mm/sparse-vmemmap: provide generic vmemmap_set_pmd() and vmemmap_check_pmd()
rust: page: mark Page::nid as inline
userfaultfd: build __VMA_UFFD_FLAGS from config-gated masks
userfaultfd: gate must_wait writability check on pte_present()
mm/huge_memory: preserve pmd_swp_uffd_wp on device-private PMD downgrade
fs/proc/task_mmu: fix hugetlb self-deadlock in pagemap_scan_pte_hole()
fs/proc/task_mmu: use huge_page_size() in pagemap_scan_hugetlb_entry()
fs/proc/task_mmu: fix make_uffd_wp_huge_pte() prot-update race
...
Lee Jia Jie reported that since event::addr_filter_ranges is used
under RCU, it should be RCU freed.
Reported-by: Lee Jia Jie <jiajie.lee@starlabs.sg>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Pull ring-buffer updates from Steven Rostedt
- Do not invalidate entire buffer for invalid sub-buffers
For the persistent ring buffer, if one sub-buffer is found to be
invalid, it invalidates the entire per CPU ring buffer. This can lose
a lot of valuable data if there's some corruption with the writes to
the buffer not syncing properly on a hard crash. Instead, if a
sub-buffer is found to be invalid, simply zero it out and mark it for
"missed events".
When the persistent ring buffer is read and a sub-buffer that was
cleared due to being invalid on boot up is discovered, the output
will show "[LOST EVENTS]" to let the user know that events were
missing at that location. Displaying the events from valid buffers
can still be useful.
- Add a test to be able to test corrupted sub-buffers
If a persistent ring buffer is created as "ptraingtest" and the new
config that adds the test is enabled, when a panic happens, the
kernel will randomly corrupt one of the per CPU ring buffers. On boot
up, the sub-buffers with the corruption should be cleared and
flagged. When reading this buffer, the missed events should should
[LOST EVENTS].
- Add commit number in the sub-buffer meta debug info
The commit is used to know the content of a meta page. Add it to the
buffer_meta file that is shown for each per CPU buffer.
- Clean up the persistent ring buffer validation code
Add some helper functions and make variable names more consistent.
* tag 'trace-ring-buffer-v7.2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
ring-buffer: Better comment the use of RB_MISSED_EVENTS
ring-buffer: Show persistent buffer dropped events in trace_pipe file
ring-buffer: Show persistent buffer dropped events in trace file
ring-buffer: Have dropped subbuffers be persistent across reboots
ring-buffer: Cleanup buffer_data_page related code
ring-buffer: Cleanup persistent ring buffer validation
ring-buffer: Show commit numbers in buffer_meta file
ring-buffer: Add persistent ring buffer invalid-page inject test
ring-buffer: Skip invalid sub-buffers when rewinding persistent ring buffer
ring-buffer: Skip invalid sub-buffers when validating persistent ring buffer
Pull tracing updates from Steven Rostedt:
- Remove a redundant IS_ERR() check
trace_pipe_open() already checks for IS_ERR() and does it again in
the return path. Remove the return check.
- Export seq_buf_putmem_hex() to allow kunit tests against them
To add Kunit tests on seq_buf_putmem_hex(), it needs to be exported.
- Replace strcat() and strcpy() with seq_buf() logic
The code for synthetic events uses a series of strcat() and strcpy()
which can be error prone. Replace them with seq_buf() logic that does
all the necessary bound checking.
- Add a lockdep rcu_is_watching() to trace_##event##_enabled() call
The trace_##event##_enabled() is a static branch that is true if the
"event" is enabled. But this can hide bugs if this logic is in a
location where RCU is disabled and not "watching". It would only
trigger if lockdep is enabled and the event is enabled.
Add a "rcu_is_watching()" warning if lockdep is enabled in that
helper function to trigger regardless if the event is enabled or not.
- Remove the local variable in the trace_printk() macro
For name space integrity, remove the _______STR variable in the
trace_printk() macro for using the sizeof() macro directly.
- Use guard()s for the trace_recursion_record.c file
- Fix typo in a comment of eventfs_callback() kerneldoc
- Use trace_call__##event() in events within trace_##event##_enabled()
A couple of events are called within an if block guarded by
trace_##event##_enabled(). That is a static key that is only enabled
when the event is enabled. The trace_call_##event() calls the
tracepoint code directly without adding a redundant static key for
that check.
- Allow perf to read synthetic events
Currently, perf does not have the ability to enable a synthetic
event. If it does, it will either cause a kernel warning or error
with "No such device". Synthetic events are not much different than
kprobes and perf can handle fine with a few modifications.
- Replace printk(KERN_WARNING ...) with pr_warn()
- Replace krealloc() on an array with krealloc_array()
- Fix README file path name for synthetic events
- Change tracing_map tracing_map_array to use a flexible array
Instead of allocating a separate pointer to hold the pages field of
tracing_map_array, allocate the pages field as a flexible array when
allocating the structure.
- Fold trace_iterator_increment() into trace_find_next_entry_inc()
The function trace_iterator_increment() was only used by
trace_find_next_entry_inc(). It's not big enough to be a helper
function for one user. Fold it into its caller.
- Make field_var_str field a flexible array of hist_elt_data
Instead of allocating a separate pointer for the field_var_str array
of the hist_elt_data structure, allocate it as a flexible array when
allocating the structure.
- Disable KCOV for trace_irqsoff.c
Like trace_preemptirq.c, trace_irqsoff.c has code that will crash
when KCOV is enabled on ARM. The irqsoff tracing can be called on ARM
because the irqsoff tracing code can be run from early interrupt code
and produce coverage unrelated to syscall inputs.
- Fix warning in __unregister_ftrace_function() called by perf
Perf calls unregister_ftrace_function() without checking if its
ftrace_ops has already been unregistered. There's an error path where
on clean up it will unregister the ftrace_ops even if it wasn't
registered and causes a warning.
* tag 'trace-v7.2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
perf/ftrace: Fix WARNING in __unregister_ftrace_function
tracing: Disable KCOV instrumentation for trace_irqsoff.o
tracing: Turn hist_elt_data field_var_str into a flexible array
tracing: Move trace_iterator_increment() into trace_find_next_entry_inc()
tracing: Simplify pages allocation for tracing_map logic
tracing: Fix README path for synthetic_events
tracing: Use krealloc_array() for trace option array growth
tracing/branch: Use pr_warn() instead of printk(KERN_WARNING)
tracing: Allow perf to read synthetic events
HID: Use trace_call__##name() at guarded tracepoint call sites
cpufreq: amd-pstate: Use trace_call__##name() at guarded tracepoint call site
tracefs: Fix typo in a comment of eventfs_callback() kerneldoc
tracing: Switch trace_recursion_record.c code over to use guard()
tracing: Remove local variable for argument detection from trace_printk()
tracepoint: Add lockdep rcu_is_watching() check to trace_##name##_enabled()
tracing: Bound synthetic-field strings with seq_buf
seq_buf: Export seq_buf_putmem_hex() and add KUnit tests
tracing: Remove redundant IS_ERR() check in trace_pipe_open()
Pull dma-mapping updates from Marek Szyprowski:
- added checks for DMA attributes in the debug code, especially to
ensure that mappings are created and released with matching
attributes (Leon Romanovsky)
- better default configuration for CMA on NUMA machines (Feng Tang)
- code cleanup in dma benchmark tool (Rosen Penev)
* tag 'dma-mapping-7.2-2026-06-16' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux:
dma: map_benchmark: turn dma_sg_map_param buf into a flexible array
dma-contiguous: simplify numa cma area handling
dma-contiguous: add kconfig option to setup numa cma area if not configured explicitly
dma-debug: Ensure mappings are created and released with matching attributes
dma-debug: Feed DMA attribute for unmapping flows too
dma-debug: Record DMA attributes in debug entry
dma-debug: Remove unused DMA attribute parameter
ntb: Use consistent DMA attributes when freeing DMA mappings
ntb: Store original DMA address for future release
Pull printk updates from Petr Mladek:
- Add upper case flavor for printing MAC addresses (%p[mM][U]) and use
it in the nintendo driver
- Fix matching of hash_pointers= parameter modes
- Fix size check of vsprintf() field_width and precision values
- Add check of size returned by vsprintf()
- Add KUnit test for restricted pointer printing (%pK)
- Some code cleanup
* tag 'printk-for-7.2' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux:
HID: nintendo: Use %pM format specifier for MAC addresses
vsprintf: Add upper case flavour to %p[mM]
lib/vsprintf: replace min_t/max_t with min/max
printk: fix typos in comments
lib/vsprintf: Require exact hash_pointers mode matches
vsprintf: Add test for restricted kernel pointers
vsprintf: Only export no_hash_pointers to test module
lib/vsprintf: Limit the returning size to INT_MAX
lib/vsprintf: Fix to check field_width and precision
Pull virtio updates from Michael Tsirkin:
- new virtio CAN driver
- support for LoongArch architecture in fw_cfg
- support for firmware notifications in vdpa/octeon_ep
- support for VFs in virtio core
- fixes, cleanups all over the place, notably:
- vhost: fix vhost_get_avail_idx for a non empty ring
fixing an significant old perf regression
- READ_ONCE() annotations mean virtio ring is now
free of KCSAN warnings
* tag 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost: (37 commits)
can: virtio: Fix comment in UAPI header
can: virtio: Add virtio CAN driver
virtio: add num_vf callback to virtio_bus
fw_cfg: Add support for LoongArch architecture
vdpa/octeon_ep: fix IRQ-to-ring mapping in interrupt handler
vdpa/octeon_ep: Add vDPA device event handling for firmware notifications
vdpa/octeon_ep: Use 4 bytes for mailbox signature
vdpa/octeon_ep: Fix PF->VF mailbox data address calculation
vhost_task_create: kill unnecessary .exit_signal initialization
vhost: remove unnecessary module_init/exit functions
vdpa/mlx5: Use kvzalloc_flex() for MTT command memory
vdpa_sim_net: switch to dynamic root device
vdpa_sim_blk: switch to dynamic root device
virtio-mem: Destroy mutex before freeing virtio_mem
virtio-balloon: Destroy mutex before freeing virtio_balloon
tools/virtio: fix build for kmalloc_obj API and missing stubs
virtio_ring: Add READ_ONCE annotations for device-writable fields
vduse: fix compat handling for VDUSE_IOTLB_GET_FD/VDUSE_VQ_GET_INFO
tools/virtio: check mmap return value in vringh_test
vhost/net: complete zerocopy ubufs only once
...
update_rlimit_cpu() converts the RLIMIT_CPU value to nanoseconds with
u64 nsecs = rlim_new * NSEC_PER_SEC;
On 32-bit kernels both rlim_new (unsigned long) and NSEC_PER_SEC
(1000000000L) are 32-bit, so the multiplication is performed in unsigned
long and truncated for rlim_new > 4 seconds before being widened to u64.
The same file already casts to u64 for the matching computation in
check_process_timers():
u64 softns = (u64)soft * NSEC_PER_SEC;
As a result, the truncated value is installed into the CPUCLOCK_PROF
expiry cache (nextevt), causing the process CPU timer to be programmed
to fire prematurely for any RLIMIT_CPU soft limit >= 5 seconds. The
actual SIGXCPU/SIGKILL decision in check_process_timers() already casts
to u64 and is therefore correct, so limit enforcement is not broken;
only the expiry-cache programming is wrong. Apply the same cast here so
both paths convert rlim_cur identically.
64-bit kernels are unaffected.
Fixes: 858cf3a8c5 ("timers/itimer: Convert internal cputime_t units to nsec")
Signed-off-by: Zhan Xusheng <zhanxusheng@xiaomi.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260616112017.1681372-1-zhanxusheng@xiaomi.com
Commit f24df84cbe ("time/jiffies: Register jiffies clocksource before
usage") moved the jiffies clocksource registration into
clocksource_default_clock(), so that it is registered lazily on the first
call. __clocksource_register() acquires clocksource_mutex, but the first
caller is timekeeping_init(), which invokes clocksource_default_clock()
while holding tk_core.lock, a raw spinlock.
Acquiring a sleeping mutex while holding a raw spinlock is invalid.
The default clocksource only has to be registered before
tk_setup_internals() consumes its mult/shift/maxadj. Neither
clocksource_default_clock(), the ->enable() callback, nor the registration
itself need tk_core.lock, so fetch and enable the clock before acquiring
the lock. This preserves the "register before usage" ordering while
keeping clocksource_mutex out of the raw spinlock section.
clocksource_default_clock() has a second caller,
clocksource_done_booting(), which invokes it with clocksource_mutex already
held. That path avoids a recursive lock because timekeeping_init() has
already run and set cs_jiffies_registered, so the registration is skipped
there. This change does not alter that; it only fixes the invalid wait
context in timekeeping_init().
Fixes: f24df84cbe ("time/jiffies: Register jiffies clocksource before usage")
Signed-off-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Reported-by: Breno Leitao <leitao@debian.org>
Reported-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Breno Leitao <leitao@debian.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260616070914.65818-1-mikhail.v.gavrilov@gmail.com
