Commit Graph

53373 Commits

Author SHA1 Message Date
Shubhang Kaushik (Ampere)
627ea30aca sched/wait: Clarify WF_SYNC wakeup semantics
The synchronous waitqueue wakeup comments currently state that a
synchronous wakee will not be migrated to another CPU. This is not
guaranteed by the scheduler wakeup path.

WF_SYNC is an advisory hint that the caller expects the waker to
schedule away soon. Scheduler classes may use it for placement or
preemption, but callers must not rely on it to prevent migration,
preserve CPU locality, or make the wakee run next.

Keep this contract next to the flag definition, remove the stale
waitqueue wording, and make the locked helper refer to the unlocked
variant.

Signed-off-by: Shubhang Kaushik (Ampere) <sh@gentwo.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Link: https://patch.msgid.link/20260922-sched-wf-sync-doc-v3-1-23ebe9e27bef@gentwo.org
2026-09-25 20:32:31 +02:00
Vincent Guittot
d2e0100827 sched/eevdf: Handle more short slice waking cases
Handle better the cases with several short slice tasks waking up
simultaneously.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260921152238.3804392-4-vincent.guittot@linaro.org
2026-09-25 12:45:59 +02:00
Vincent Guittot
4bf32ec332 sched/eevdf: Align update_protect_slice to set_protect_slice
Apply the same logic as for set_protect_slice when updating it.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260921152238.3804392-3-vincent.guittot@linaro.org
2026-09-25 12:45:59 +02:00
Vincent Guittot
aae2a33ea6 sched/eevdf: Ensure that vprot will never go above a min slice
ineligible_vruntime() can be after the duration of a min slice but we
want to make sure that current will not run more than a min slice.

Signed-off-by: Vincent Guittot <vincent.guittot@linaro.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260921152238.3804392-2-vincent.guittot@linaro.org
2026-09-25 12:45:58 +02:00
Christian Loehle
c9ce69fc43 sched/fair: Randomize equally shallow slow-path candidates
Picking the first eligible idle CPU leaves a scan-order bias. Concurrent
slow-path selectors can choose the same CPU before either task is enqueued.

Use reservoir sampling for equal exit latencies, resetting the candidate
count when a shallower candidate appears. Use the per-CPU scheduler PRNG
and reciprocal_scale() to avoid variable division or a second scan.

Use a u64 latency key with U64_MAX for unpublished states. Published
states take precedence; when none are found, sample among the idle CPUs
without a published state.

Signed-off-by: Christian Loehle <christian.loehle@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://patch.msgid.link/20260917153915.1563875-3-christian.loehle@arm.com
2026-09-25 12:45:58 +02:00
Christian Loehle
abe440b377 sched/fair: Drop idle recency from slow-path CPU selection
The slow-path CPU picker favours the most recently idle CPU as a proxy
for cache warmth.

A more recent idle stamp may make ongoing entry more likely. If entry
cannot be aborted, that CPU must finish entry and then exit, potentially
paying more than an already-resident CPU with the same advertised exit
latency. The advertised worst-case latency covers both cases. idle_stamp
does not timestamp the current CPUIdle entry, so this is only a heuristic.

A recent scheduler-idle transition may also mark a short gap in recurring
task activity, making the CPU likely to be busy again soon.

Drop the timestamp tie-break and retain the first candidate unless a
lower advertised exit latency is found.

Signed-off-by: Christian Loehle <christian.loehle@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://patch.msgid.link/20260917153915.1563875-2-christian.loehle@arm.com
2026-09-25 12:45:58 +02:00
Hui Su
fbbc63fed0 sched/core: Remove redundant core_sched_seq
core_sched_seq records whether an rq has consumed the pick made by the
last core-wide selection.

However, rq->core_pick already carries the same per-rq state. A core-wide
selection leaves core_pick populated only for siblings which still need to
consume their picks. It is cleared when the current CPU consumes its pick,
when a sibling is already running the selected task, or when a pending pick
is consumed through the fastpath. The CPU offline path clears it as well.

core_task_seq and core_pick_seq serve a separate purpose. core_task_seq
changes when the task set changes and for each new core-wide pick, while
core_pick_seq records the task sequence on which the selection was made.
Their equality therefore establishes that a pending core_pick is still
valid.

Consequently, once core_pick_seq == core_task_seq, a non-NULL core_pick is
sufficient to tell that this rq still has a pick to consume.
core_sched_seq duplicates that pending/consumed state.

Remove core_sched_seq and use core_pick directly as the pending marker.

Testing included an instrumented comparison of the old and new pending
predicates under core-scheduling stress. Additional guest tests exercised
repeated core-cookie lifecycles, forced idle, and CPU hotplug under load.
No predicate divergence or kernel warning was observed.

Signed-off-by: Hui Su <sh_def@163.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260915163138.2973969-1-sh_def@163.com
2026-09-25 12:45:58 +02:00
Kayra Cizmeci
819224e506 sched/fair: Remove dead code on enqueue_task_fair()
The 'cfs_rq->curr == se' path on enqueue_task_fair() seems to be unachievable.

Remove the code that depends on this cfs_rq->curr == se case on
enqueue_task_fair() and bool curr too since there are two possibilities
and one has been removed, we can proceed directly with the other.

Signed-off-by: Kayra Cizmeci <kayracizmeci@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260911155449.1249726-1-kayracizmeci@gmail.com
2026-09-25 12:45:57 +02:00
Shubhang Kaushik (Ampere)
c72945693b sched: Restart fair hrtick after same-task repicks
Fair hrticks are one-shot timers. A same-task repick after hrtick expiry
skips set_next_task_fair() and leaves no hrtick armed for the next fair
preemption point:

    hrtick()
      -> task_tick_fair(..., queued=1)
         -> entity_tick()
            -> resched_curr()
      -> schedule()
         -> pick_task_fair() selects current
         -> put_prev_set_next_task(rq, prev, next)
            -> next == prev
            -> return

Introduce SNT_REPICK for the next == prev path:

    put_prev_set_next_task(rq, prev, next)
      -> next == prev
      -> next->sched_class->set_next_task(rq, next, SNT_REPICK)
         -> set_next_task_fair()
            -> hrtick_start_fair()

set_next_task_fair() skips task-transition work for SNT_REPICK and
restarts the fair hrtick. hrtick_start() records the delay during
schedule(), and hrtick_schedule_exit() rearms the timer.

Do not restart the SCHED_DEADLINE hrtick for SNT_REPICK. Same-task
repicks skip put_prev_task() for both fair and SCHED_DEADLINE, but
pick_task_fair() refreshes the selected fair entity before selecting it
again. hrtick_start_fair() reads that refreshed entity, including with
group scheduling.

The SCHED_DEADLINE picker has no corresponding current-runtime update.
Restarting its hrtick on SNT_REPICK could therefore use stale
dl_se->runtime and delay the next runtime enforcement point.

Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Shubhang Kaushik (Ampere) <sh@gentwo.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Zhan Xusheng <zhanxusheng@xiaomi.com>
Link: https://patch.msgid.link/20260917-sched-fair-hrtick-restart-v4-1-4dd1414da81a@gentwo.org
2026-09-25 12:45:57 +02:00
Eric Kim
e81ee06308 sched/fair: Reset NUMA fault locality after scan period update
When updating the task scan period for NUMA locality checks,
update_task_scan_period() checks whether there were no faults or failed
migration on the last scan window, at which it prolongs the scan period.

However, p->numa_faults_locality, which is used to check for migration
failure and number of faults at the previous scan window is not cleared
after changing the scan period, which unintentionally increases
numa_scan_period up to numa_scan_period_max even when there were no
migration failures or no faults at previous scan.

Fix this by jumping to the out label on early exit at this case to
ensure p->numa_faults_locality is always cleared before returning.

Closes: https://lore.kernel.org/all/20250404095354.311156-1-qlsdnjs236@chungbuk.ac.kr/
Reported-by: Binwon Song <qlsdnjs236@chungbuk.ac.kr>
Signed-off-by: Eric Kim <seohyun.kim@outlook.kr>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/Message-ID:
2026-09-10 11:01:30 +02:00
Mark Rutland
ef9293b3b7 sched: dynamic: Fix preemption model strings
We recently removed the enum values 'preempt_dynamic_none' and
'preempt_dynamic_voluntary', but forgot to update preempt_modes[]
accordingly. Due to this, preempt_model_str() and sched_dynamic_show()
produce incorrect output, with the wrong preemption model string in
backtraces, and empty output for /sys/kernel/debug/sched/preempt.

Update preempt_modes[] to account for the removed enum values. Given
that CONFIG_PREEMPT_DYNAMIC now depends on CONFIG_ARCH_HAS_PREEMPT_LAZY,
and given that only 'preempt_dynamic_full' and 'preempt_dynamic_lazy'
remain, sched_dynamic_show() no longer needs to skip any model strings.

Fixes: 9650ce11f2 ("sched: dynamic: Simplify preempt model accessors")
Reported-by: Jinjie Ruan <ruanjinjie@huawei.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260902101637.232129-1-mark.rutland@arm.com
2026-09-02 12:54:21 +02:00
Vladimir Zapolskiy
879eaa76e6 sched: Remove unneeded function type cast in do_balance_callbacks()
It's a trivial and non-functional change, the removed explicit function
type cast does not convert the function type of struct balance_callback
member (*func), and the cast can be removed.

Signed-off-by: Vladimir Zapolskiy <vz@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260819080159.105433-1-vz@kernel.org
2026-09-02 10:28:25 +02:00
Liang Hao
f549101187 sched/deadline: check start_dl_timer expiry with ktime_before()
Replace ktime_us_delta() < 0 with ktime_before() so the past-expiry
test uses the same resolution as act/now.

Signed-off-by: Liang Hao <haohlliang@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Link: https://patch.msgid.link/20260816032643.44969-1-haohlliang@gmail.com
2026-09-02 10:28:24 +02:00
Hongyan Xia
2a672daa4b sched/feat: Use the new static key API for sched_feat
Both raw static keys and static_key_true/false() have been deprecated.
Migrate to new API.

It's a bit tricky to convert the sched_feat array to the new API because
the new one has two different types for true and false keys. Use a union
to wrap it.

No functional change.

Signed-off-by: Hongyan Xia <hongyan.xia@transsion.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260819081312.12447-1-hongyan.xia@transsion.com
2026-09-02 10:28:24 +02:00
Hongyan Xia
a5576ebce9 sched: Convert paravirt_steal to new static key APIs
paravirt_steal_rq_enabled and paravirt_steal_enabled use raw static_key
APIs which are now deprecated. Use the new API instead.

No functional change.

Signed-off-by: Hongyan Xia <hongyan.xia@transsion.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juergen Gross <jgross@suse.com>
Link: https://patch.msgid.link/20260819081207.12150-1-hongyan.xia@transsion.com
2026-09-02 10:28:24 +02:00
Mark Rutland
9650ce11f2 sched: dynamic: Simplify preempt model accessors
PREEMPT_DYNAMIC is now limited to the FULL and LAZY preemption models.
When CONFIG_PREEMPT_DYNAMIC=y, the NONE and VOLUNTARY models cannot be
used, and neither CONFIG_PREEMPT_NONE nor CONFIG_PREEMPT_VOLUNTARY can
be selected.

Simplify the preempt model accessors accordingly: remove the out-of-line
implementations of preempt_model_none() and preempt_model_voluntary(),
and remove the preempt_dynamic_{none,voluntary} values.

There are no current users of preempt_model_voluntary(), but I've kept
it around for consistency, with every scheduler model having its own
preempt_model_*() accessor.

Suggested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Tested-by: Mete Durlu <meted@linux.ibm.com>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Tested-by: Jinjie Ruan <ruanjinjie@huawei.com>
Link: https://patch.msgid.link/20260803191731.3244294-7-mark.rutland@arm.com
2026-09-02 09:37:24 +02:00
Mark Rutland
5b9a28eeed sched: dynamic: Remove HAVE_PREEMPT_DYNAMIC_{CALL,KEY}
PREEMPT_DYNAMIC is now limited to the FULL and LAZY preemption models.
Switching model only changes the behaviour of dynamic_preempt_lazy(),
which uses a static key. There are no other static calls or static keys,
and so there's no need for HAVE_PREEMPT_DYNAMIC_CALL or
HAVE_PREEMPT_DYNAMIC_KEY.

The static key used by dynamic_preempt_lazy() is entirely local to
kernel/sched/core.c, and any architecture which selects
ARCH_HAS_PREEMPT_LAZY implements the necessary support. Remove
PREEMPT_DYNAMIC's dependencies on HAVE_PREEMPT_DYNAMIC_CALL and
HAVE_PREEMPT_DYNAMIC_KEY entirely, leaving the dependency on
ARCH_HAS_PREEMPT_LAZY.

For architectures which previously selected HAVE_PREEMPT_DYNAMIC_KEY,
PREEMPT_DYNAMIC will now be selected by default, matching x86. As the
runtime impact is limited to dynamic_preempt_lazy(), this shouldn't be
as concerning as previously (e.g. where calls to {cond,might}_resched()
stubs could introduce a measurable penalty).

As all of this can work without jump labels, JUMP_LABEL is not selected
explicitly. It is obviously preferable to have JUMP_LABEL enabled, but
this is not functionally necessary.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Tested-by: Mete Durlu <meted@linux.ibm.com>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Tested-by: Jinjie Ruan <ruanjinjie@huawei.com>
Link: https://patch.msgid.link/20260803191731.3244294-6-mark.rutland@arm.com
2026-09-02 09:37:23 +02:00
Mark Rutland
aa4178f638 sched: dynamic: Simplify irqentry_exit_cond_resched()
PREEMPT_DYNAMIC is now limited to the FULL and LAZY preemption models.
In either model, irqentry_exit_cond_resched() is always called and never
disabled.

Remove the unnecessary code for this when PREEMPT_DYNAMIC is selected.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
Tested-by: Mete Durlu <meted@linux.ibm.com>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Tested-by: Jinjie Ruan <ruanjinjie@huawei.com>
Link: https://patch.msgid.link/20260803191731.3244294-5-mark.rutland@arm.com
2026-09-02 09:37:23 +02:00
Mark Rutland
b9d267b9d6 sched: dynamic: Simplify preempt_schedule{,_notrace}()
PREEMPT_DYNAMIC is now limited to the FULL and LAZY preemption models.
In either model, both preempt_schedule() and preempt_schedule_notrace()
are always called and never disabled.

Remove the unnecessary code for these when PREEMPT_DYNAMIC is selected.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
Tested-by: Mete Durlu <meted@linux.ibm.com>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Tested-by: Jinjie Ruan <ruanjinjie@huawei.com>
Link: https://patch.msgid.link/20260803191731.3244294-4-mark.rutland@arm.com
2026-09-02 09:37:22 +02:00
Mark Rutland
88e0b3bb99 sched: dynamic: Simplify {cond,might}_resched()
PREEMPT_DYNAMIC is now limited to the FULL and LAZY preemption models.
In either model, both cond_resched() and might_resched() are always
disabled and do nothing.

Remove the unnecessary code for these when PREEMPT_DYNAMIC is selected.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
Tested-by: Mete Durlu <meted@linux.ibm.com>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Tested-by: Jinjie Ruan <ruanjinjie@huawei.com>
Link: https://patch.msgid.link/20260803191731.3244294-3-mark.rutland@arm.com
2026-09-02 09:37:22 +02:00
Mark Rutland
d3d1675069 sched: dynamic: Make PREEMPT_DYNAMIC depend on ARCH_HAS_PREEMPT_LAZY
On architectures which select ARCH_HAS_PREEMPT_LAZY, it has not been
possible to select the NONE and VOLUNTARY preemption models since
commit:

  7dadeaa6e8 ("sched: Further restrict the preemption modes")

... which was merged in v7.0.

All architectures which currently support PREEMPT_DYNAMIC select
ARCH_HAS_PREEMPT_LAZY:

  [mark@lakrids:~/src/linux]% git describe HEAD
  v7.2-rc1-1-g871a4586ea2e1
  [mark@lakrids:~/src/linux]% git grep 'select HAVE_PREEMPT_DYNAMIC_' -- arch
  arch/arm64/Kconfig:     select HAVE_PREEMPT_DYNAMIC_KEY
  arch/loongarch/Kconfig: select HAVE_PREEMPT_DYNAMIC_KEY
  arch/powerpc/Kconfig:   select HAVE_PREEMPT_DYNAMIC_KEY
  arch/riscv/Kconfig:     select HAVE_PREEMPT_DYNAMIC_KEY
  arch/s390/Kconfig:      select HAVE_PREEMPT_DYNAMIC_KEY
  arch/x86/Kconfig:       select HAVE_PREEMPT_DYNAMIC_CALL
  [mark@lakrids:~/src/linux]% git grep 'select ARCH_HAS_PREEMPT_LAZY' -- arch
  arch/arm64/Kconfig:     select ARCH_HAS_PREEMPT_LAZY
  arch/loongarch/Kconfig: select ARCH_HAS_PREEMPT_LAZY
  arch/powerpc/Kconfig:   select ARCH_HAS_PREEMPT_LAZY
  arch/riscv/Kconfig:     select ARCH_HAS_PREEMPT_LAZY
  arch/s390/Kconfig:      select ARCH_HAS_PREEMPT_LAZY
  arch/x86/Kconfig:       select ARCH_HAS_PREEMPT_LAZY

... and hence in practice PREEMPT_DYNAMIC no longer supports the NONE or
VOLUNTARY preemption models.

Make this official: have PREEMPT_DYNAMIC depend on
ARCH_HAS_PREEMPT_LAZY, and remove the trivially unreachable code.
Further simplifications will be made in subsequent patches.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Reviewed-by: Jinjie Ruan <ruanjinjie@huawei.com>
Tested-by: Mete Durlu <meted@linux.ibm.com>
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Tested-by: Jinjie Ruan <ruanjinjie@huawei.com>
Link: https://patch.msgid.link/20260803191731.3244294-2-mark.rutland@arm.com
2026-09-02 09:37:22 +02:00
John Stultz
772d9ffbfd sched: Migrate whole chain in proxy_migrate_task()
Instead of migrating one task each time through find_proxy_task(),
we can walk up the blocked_donor ptrs and migrate the entire
current chain in one go.

This was broken out of earlier patches and held back while the
series was being stabilized, but I wanted to re-introduce it.

Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260807035232.1881495-8-jstultz@google.com
2026-09-02 09:37:21 +02:00
John Stultz
6b73a09e94 sched: Break out core of attach_tasks() helper into sched.h
Pull the core of attach_tasks() out into sched.h so
it can be used more generically.

Suggested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260807035232.1881495-7-jstultz@google.com
2026-09-02 09:37:21 +02:00
John Stultz
1f88051385 sched: Switch rq->next_class in proxy_reset_donor()
Similar to commit 04f80f8b12 ("sched: Switch rq->next_class on
proxy_resched_idle()"), we should also set the rq->next_class
when we call proxy_reset_donor().

Fixes: f13beb010e ("sched: Have try_to_wake_up() handle return-migration for PROXY_WAKING case")
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260807035232.1881495-6-jstultz@google.com
2026-09-02 09:37:21 +02:00
Vasily Gorbik
09351db90a sched/core: Don't proxy-exec unmatched cookie lock owners
Core scheduling chooses a core-wide cookie before __schedule()
installs the next task. With proxy-exec enabled, that task becomes the
donor/scheduling context, and find_proxy_task() may then replace the
execution context with the runnable mutex owner. If its cookie differs
from the selected core cookie, running it would bypass core scheduling's
cookie selection.

When the final mutex owner found by find_proxy_task() does not match the
selected core cookie, stop proxying the donor. If the current execution
context is already in the blocked chain, fall back to idle like the
existing proxy-exec retry paths do. Otherwise deactivate the donor and
let __schedule() pick again. The mutex owner can be picked later under
its own cookie.

Fixes: 7de9d4f946 ("sched: Start blocked_on chain processing in find_proxy_task()")
[jstultz: Added tweak to ensure we deactivate donor, not runnable owner]
Reported-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/lkml/10282ce9-f4ae-498f-9b57-f4e1e61fffbc@amd.com/
Link: https://patch.msgid.link/20260807035232.1881495-5-jstultz@google.com
2026-09-02 09:37:20 +02:00
John Stultz
9be817f991 sched/core: Avoid migrating blocked_on tasks
Its not useful to migrate blocked_on tasks from other
runqueues as the proxy logic will just migrate it
back to the owner's rq. So skip blocked_on tasks here.

Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260807035232.1881495-4-jstultz@google.com
2026-09-02 09:37:20 +02:00
Vasily Gorbik
3dd95f0773 sched/core: Don't steal a proxy-exec donor
try_steal_cookie() avoids stealing src->core_pick and src->curr before
moving a task with the same cookie via move_queued_task_locked().

With proxy-exec, src->donor is the current scheduling context and may
differ from src->curr. Stealing it migrates a task that the source rq
still treats as current, leaving src's scheduler state for that task
stale. For CFS this means cfs_rq->curr points at the stolen entity,
and the next pick on the source rq hits the WARN_ON_ONCE in
put_prev_entity().

Commit 7de9d4f946 ("sched: Start blocked_on chain processing in
find_proxy_task()") tweaked the fair class logic so that the donor task
isn't migrated away while we're running the proxy. Do it similarly for
try_steal_cookie() and skip src->donor as well.

Fixes: 7de9d4f946 ("sched: Start blocked_on chain processing in find_proxy_task()")
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260807035232.1881495-3-jstultz@google.com
2026-09-02 09:37:20 +02:00
Tim Chen
f0d243a96f sched/fair: Avoid creating misfits during cache-aware balancing
Cache-aware load balancing biases tasks toward their preferred LLC. On
asymmetric CPU capacity systems (e.g. big.LITTLE) the destination LLC may
contain CPUs that are too small to run the task. Pulling the task there
turns it into a misfit, trading a cache-locality gain for a capacity loss
that's more detrimental to performance.

Guard both cache-aware migration entry points against this:

 - can_migrate_llc_task(): forbid the LLC migration when the task fits its
   source CPU but would not fit the destination CPU.
 - alb_break_llc(): veto the active balance under the same condition so the
   runnable task is not pushed onto a CPU that cannot accommodate it.

Both checks are gated with checks for hybrid processors, so symmetric
systems are unaffected. Tasks that already do not fit their source CPU
are left to the existing LLC policy, since the move cannot make their
fitness worse (this also preserves misfit up-migration to bigger CPUs).

Additionally, if there are misfit tasks found in the load balancing
classification phase, prioritize misfit task migrations
over LLC load aggregation on asymmetric systems. A better fitting
CPU will boost performance more than better cache locality.

Reviewed-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Tested-by: Ricardo Neri <ricardo.neri-calderon@linux.intel.com>
Reviewed-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/edbb2503d554c63dc9b72e201fb4a17e1cb119e7.camel@linux.intel.com
2026-09-02 09:17:50 +02:00
Wanwu Li
b038383526 sched/fair: Use cfs_rq->h_curr in distribute_cfs_runtime()
distribute_cfs_runtime() refreshes the rq clock and accounts elapsed
runtime with update_curr() before redistributing bandwidth, but gates
this on cfs_rq->curr. Since commit 85570f10a4 ("sched/eevdf: Move to
a single runqueue") cfs_rq->curr is only maintained on the root
cfs_rq, so for the cgroup cfs_rqs it walks, the check never fires and
the refresh is dead code.

Use cfs_rq->h_curr, the per-level current entity, restoring the
intended behaviour: only refresh when something is actually running at
the throttled level, i.e. within the deferred throttle window.
Without this, runtime consumed by a still-running task of the
throttled hierarchy is not docked before redistribution;
unthrottle_cfs_rq() catches up unconditionally since
commit 28ad542768 ("sched/fair: Call update_curr() before
unthrottling the hierarchy"), so this is not a correctness hole today,
but the refresh the check was written for is gone.

Fixes: 85570f10a4 ("sched/eevdf: Move to a single runqueue")
Signed-off-by: Wanwu Li <liwanwu@kylinos.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Aaron Lu <ziqianlu@bytedance.com>
Tested-by: Aaron Lu <ziqianlu@bytedance.com>
Link: https://patch.msgid.link/20260831101141.391382-3-liwanwu@kylinos.cn
2026-09-02 09:17:50 +02:00
Wanwu Li
f8610c57f4 sched/fair: Use cfs_rq->h_curr in throttle_cfs_rq()
After commit 85570f10a4 ("sched/eevdf: Move to a single runqueue"),
cfs_rq->curr is only maintained on the root cfs_rq (set/cleared from
set_next_task_fair()/put_prev_task_fair()), while cfs_rq->h_curr is
the per-level current entity, set by set_next_entity() at every level
of the hierarchy. For an intermediate cfs_rq (a cgroup), cfs_rq->curr
is always NULL, but cfs_rq->h_curr is the group entity at that level.

throttle_cfs_rq() reads cfs_rq->curr to decide whether there is a
running entity at the throttled level, in which case it should request
a full sched_cfs_bandwidth_slice() of runtime and arm the deferred
throttle task_work via task_throttle_setup_work(). For intermediate
cfs_rqs the check is always false, so bandwidth-controlled cgroups
always get just 1ns of runtime and never arm the deferred throttle
work; the running task then escapes throttling until the next pick
arms the work instead, even though there is an on-rq entity at this
level.

Switch the read to cfs_rq->h_curr so intermediate bandwidth-controlled
cgroups behave consistently with the root cfs_rq, matching the
existing usage of cfs_rq->h_curr in update_curr() and
check_enqueue_throttle().

Fixes: 85570f10a4 ("sched/eevdf: Move to a single runqueue")
Signed-off-by: Wanwu Li <liwanwu@kylinos.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Aaron Lu <ziqianlu@bytedance.com>
Tested-by: Aaron Lu <ziqianlu@bytedance.com>
Link: https://patch.msgid.link/20260831101141.391382-2-liwanwu@kylinos.cn
2026-09-02 09:17:49 +02:00
Shubhang Kaushik (Ampere)
c6dcd97c8b sched/core: Skip rq->avg_idle update without a valid idle_stamp
Commit 4b603f1551 ("sched: Update rq->avg_idle when a task is moved
to an idle CPU") moved rq->avg_idle accounting out of the wakeup path and
into put_prev_task_idle(), so that the idle interval is consumed whenever
the idle task is switched out.

The wakeup-side accounting that it replaced only updated rq->avg_idle
when rq->idle_stamp was non-zero. The new helper lost that validity
check and unconditionally computes:

	rq_clock(rq) - rq->idle_stamp

If rq->idle_stamp is zero, this uses rq_clock(rq) as the sample. That is
not a valid idle duration and can immediately drive rq->avg_idle to its
clamp.

This can happen when sched_balance_newidle() returns before setting
rq->idle_stamp, for example when this_rq->ttwu_pending is set. In that
case the rq can switch to the idle task with idle_stamp still zero and
leave idle again when the pending wakeup is processed.

Other paths can also switch to the idle task without setting
rq->idle_stamp via newidle_balance(), for example find_proxy_task() or
force-idling.

Restore the idle_stamp validity check in update_rq_avg_idle() and skip
the rq->avg_idle update when there is no measured idle interval.

Fixes: 4b603f1551 ("sched: Update rq->avg_idle when a task is moved to an idle CPU")
Signed-off-by: Shubhang Kaushik (Ampere) <sh@gentwo.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Acked-by: John Stultz <jstultz@google.com>
Link: https://patch.msgid.link/20260807-master-v3-1-c328354efed3@gentwo.org
2026-09-02 09:17:49 +02:00
Seiji Nishikawa
dae5c02920 sched/rt,dl: Skip migrate-disabled tasks when picking a push candidate
A migrate_disable()'d RT task cannot be moved to another CPU, but the
scheduler still keeps such a task on that CPU's pushable list
(rq->rt.pushable_tasks) and still marks the runqueue RT-overloaded
(rq->rt.overloaded = 1). So the RT balancer keeps treating this CPU as
having a task to move away, and keeps trying to move the task, but the
push can never succeed. When the head is pinned, push_rt_task() does not
give up either. It falls back to pushing rq->curr instead, using the
per-CPU stopper, as added by commit a7c81556ec ("sched: Fix
migrate_disable() vs rt/dl balancing").

The CPU spends tens of milliseconds in this retry loop. The core is
isolated for real-time work, but during the loop nearly half of its time
is consumed by pushes that cannot succeed.

An ftrace capture of the affected CPU, with sched_switch enabled and
commit 94894c9c47 ("sched/rt: Skip currently executing CPU in
rto_next_cpu()") applied, shows where the CPU time went. Two SCHED_FIFO
tasks at equal priority shared the CPU, taskA migrate_disable()'d and
queued, taskB as rq->curr. In one 89 ms window, taskB got only 52 ms of
CPU. The other 37 ms went to the stopper thread.

The scheduler kept trying to push taskA, the pinned head of the pushable
list, fell back to pushing taskB instead, and woke the stopper 5204
times. Every one of those pushes failed and no task was moved. taskA
stayed runnable and queued the whole time, and never ran.

Pushing taskB fails on a re-check. find_lock_lowest_rq() drops the rq
lock to take the target rq lock, then checks again with
"task != pick_next_pushable_task(rq)".

The task being pushed is taskB, but the pick returns taskA, the head of
the pushable list. taskB is rq->curr, and set_next_task_rt() removes the
running task from that list, so taskB can never be the head. The check
expects a candidate taken from the pushable list, but the fallback
pushes rq->curr, which is never on that list. So the check fails every
time.

   .--> push-IPI arrives
   |          |
   |          v
   |     pushable head = taskA   ->  pinned, cannot be pushed
   |          |
   |          v
   |     so push taskB instead   ->  wake migration/N, a stop-class
   |          |                      thread, so it preempts taskB
   |          v
   |     re-check compares taskB against the pushable head,
   |     which is still taskA                        ->  give up
   |          |
   |          v
   |     nothing moved, taskA still queued, rq still overloaded
   |          |
   '----------'
         repeats every ~17 us, 5204 times, for 89 ms

   The loop cannot stop itself. Every round leaves the runqueue
   exactly as it was, so the next push-IPI does the same thing. In
   the capture it ended only when taskB went to sleep on its own.
   taskA was then picked locally and left the pushable list.

   CPU time per task in the window, from sched_switch:

     taskB         51.95 ms   real work
     migration/N   37.18 ms   nothing moved
     taskA          0.00 ms   queued the whole time, never picked
     idle           0.01 ms

   Counts over the same window:

      7667  push-IPIs handled on this CPU
     17481  pick_next_pushable_task() returned taskA, still pinned
      5204  find_lock_lowest_rq() gave up on the re-check
         1  push that actually completed
         0  migrations of taskA

   The CPU times and the window length come from the standard
   sched_switch tracepoint. The counts needed tracepoints added inside
   the RT balancer for this investigation.

The self-IPI path is closed by the rto_next_cpu() fix above, and that
part works. But the runqueue is still marked overloaded, because the
pinned task is still advertised as pushable. Other CPUs now send the
push-IPIs during their own RT balancing, and the same loop runs again.
Closing the self-IPI path did not stop a pinned task from triggering
push balancing.

A pinned task should never have been returned as a push candidate in the
first place. A migrate_disable()'d task cannot be migrated, so it
belongs in the same skip that was added for on_cpu tasks by
commit e0ca8991b2 ("sched: Make class_schedulers avoid pushing
current, and get rid of proxy_tag_curr()"). Add is_migration_disabled()
to the skip condition in pick_next_pushable_task() and
pick_next_pushable_dl_task().

With the skip in place, if the pinned task is the only extra runnable
task the helpers return NULL, push_rt_task() and push_dl_task() give up
early, and no stopper is woken. The pinned task then runs locally once
curr yields. If a task that really can be migrated is queued behind the
pinned head, it is now picked and pushed for real.

This makes the fallback that pushes rq->curr unreachable when the
pushable head is migrate-disabled. Nothing is lost, because that path
was always stopped by the re-check described above. In the capture it
ran 5204 times and moved nothing.

Fixes: a7c81556ec ("sched: Fix migrate_disable() vs rt/dl balancing")
Signed-off-by: Seiji Nishikawa <snishika@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260830073746.2189355-1-snishika@redhat.com
2026-09-02 09:17:49 +02:00
Zhan Xusheng
1719d035a6 sched/fair: Use update_curr_eevdf() for the remaining root cfs_rq callers
pick_task_fair() and yield_task_fair() call update_curr(&rq->cfs) to bring
curr up to date before they look at the eevdf state.  With cgroups that
does not happen: update_curr() reads ->h_curr, which on the root cfs_rq is
the top level group entity, and returns at the !entity_is_task() check
before touching vruntime.  Both then read ->curr, so the guard and the
update disagree about which entity they mean.

Counting how often ->h_curr and ->curr differ at pick_task_fair(), on one
CPU for 10s with three busy tasks and one 200us-periodic task:

  all tasks in the root cgroup        43321 calls,     0 no-ops
  busy tasks in G0, periodic in G1    45211 calls, 45193 no-ops

Whether that matters depends on what precedes the pick.  Since
commit 68e3748781 ("sched/fair: Fix flat hierarchy") the tick and
enqueue/dequeue all update curr correctly, so on the normal reschedule
path only the microseconds between those and the pick are missing, and I
could not measure a latency difference there.  Three paths have nothing
before them on that rq though:

  - pick_task() on the sibling rqs of a core under core scheduling
    (kernel/sched/core.c), which updates that rq's clock first for
    exactly this reason
  - fair_server_pick_task()
  - yield_task_fair(), where the stale value feeds the entity_eligible()
    test that guards forfeiting the remaining vruntime

There curr can be a full tick behind, as it was before that commit.

No new behaviour for the entity being updated: without cgroups ->h_curr
is already the task, so these two call sites already run the full
update_curr() including update_deadline(), dl_server_update() and the
resched_curr_lazy() at the end.  This makes the cgroup case do the same.

Fixes: 85570f10a4 ("sched/eevdf: Move to a single runqueue")
Signed-off-by: Zhan Xusheng <zhanxusheng@xiaomi.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Vincent Guittot <vincent.guittot@linaro.org>
Link: https://patch.msgid.link/20260822105930.2352761-1-zhanxusheng1024@gmail.com
2026-09-02 09:17:49 +02:00
Linus Torvalds
637836563d - Revert a commit to spinlock cleanup guards that got caught up
in the subtle limitations & fragility of guards (again...) and
    caused a regression (Peter Zijlstra)
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'locking-urgent-2026-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking fix from Ingo Molnar:

 - Revert a commit to spinlock cleanup guards that got caught up
   in the subtle limitations & fragility of guards (again...) and
   caused a regression (Peter Zijlstra)

* tag 'locking-urgent-2026-08-30' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking: Revert switching guards to _irq_{disable,enable}()
2026-08-30 09:57:35 -07:00
Linus Torvalds
034dd340b0 tracing fixes for v7.3:
- Fix error output of boot instance creation failure
 
   Currently if a boot instance creation fails, instead of printing out the
   name of the instance that failed, it prints "(null)". That is because it
   prints "cur_str" that had already been processed by strsep(). Print the
   saved name instead.
 
   While at it, print the error code of the failure.
 
 - Fix use-after-free for same named historgrams
 
   Histograms can be named so that they can be used in multiple events. But
   if the named histogram has a variable attached, the second event that uses
   the named histogram which duplicates it and needs to free the original
   after duplication leaves the old variable in place and still visible. If
   another histogram uses than variable, it will use the stale one which will
   try to reference the freed duplicate histogram and crash the kernel.
 
   Free the duplicate variables along with the duplicated histogram data.
 
 - Check return value of kthread_run() in event self test
 
   The events self tests uses a kthread for testing but does not check if it
   succeeded in creating a kthread. If the kthread creation were to fail, the
   code will still try to call kthread_stop() on the error returned.
 
 - Fix race between reading trace_pipe and updating subbuffer size
 
   If a user is reading the trace_pipe file at the same time they update the
   ring buffer sub-buffer size, can cause the trace_pipe read to read stale
   data. Add trace_access_lock() around updating the ring buffer sub-buffer
   size.
 
 - Fix eventfs_inode on failure path in creation of the events directory
 
   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which calls
   free_ei(). The free_ei() will test if eventfs_inode being freed has no
   children. It is a bug if it does. But on the failure case of the creation
   of the "events" directory, the children lists have not yet been
   initialized and the free will trigger a warning because list_empty() on an
   uninitialized list returns false.
 
   Move the initialization into init_ei() where it makes more sense and makes
   sure that a created eventfs_inode has its lists initialized upon creation.
 
 - Check return value of kthread_run() in ftrace direct sample code
 
   The sample code that shows how to use the ftrace direct calls does not
   test the return of kthread_run() to see if it succeeds. Return a failure
   if the kthread_run() doesn't succeed.
 
 - Clear user events state on fork in case of alloc failure
 
   On fork, the child gets a pointer to the parent's user events state. It
   makes a copy of it then updates the child's pointer to it. But if the
   allocation fails, the duplication function leaves the child with a pointer
   to its parent's descriptor. When the child cleans up its data, it will free
   the parent's descriptor while the parent is still using it.
 
   In the duplication function, set the child's user_event_mm to NULL before
   testing if the allocation succeeded, and when it exits it will not free
   the parent's descriptor.
 
 - Fix retry exhaustion in simple ring buffer reader swap
 
   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a failed
   replacement leaves it at -1.
 
   But the check for success expects the retry value to be non-zero and exits
   with an error on zero. This is the opposite result. Fix it.
 
 - Fail nicely when the remote swap_reader_page() returns an error
 
   Currently, if the swap_reader_page() of a remote buffer fails, it triggers
   a WARN_ON_ONCE() and continues normally. Instead, have it exit with an
   error and a pr_warn() print instead of a full WARNING.
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Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure
2026-08-30 09:22:00 -07:00
Ivan Immanuel Shaji
5eab74874d ring-buffer: Stop remote reader update when page swap fails
The remote swap_reader_page callback can return -EBUSY when the writer
moves the head before the remote catches it, particularly during an event
storm on a small buffer. __rb_get_reader_page_from_remote() currently
warns about that failure but continues with the unchanged reader ID and
rearranges the local page list as though the swap succeeded.

Handle the callback failure as a recoverable error. Report it with
pr_warn_ratelimited() and return NULL. Callers already handle a NULL reader
page as a failed attempt. This avoids splicing the same page as both the
previous and new reader without flooding the log under contention.

Cc: stable@vger.kernel.org
Fixes: 2e67fabd8b ("ring-buffer: Introduce ring-buffer remotes")
Link: https://patch.msgid.link/20260825-kernel-patch-1-v2-2-bb3461807a32@gmail.com
Assisted-by: LLM sparse
Signed-off-by: Ivan Immanuel Shaji <ivanimmanuel1234@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2026-08-27 21:31:51 -04:00
Ivan Immanuel Shaji
e0d3aed7b1 tracing: Fix retry exhaustion in simple ring buffer reader swap
simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
post-decrements it only after a failed link replacement. On the final
attempt, a successful replacement leaves retry at zero, while a failed
replacement leaves it at -1.

The current !retry test reverses both outcomes. It returns an error after
a successful final replacement, leaving the link update complete but the
reader bookkeeping unfinished. After a failed final replacement, it
falls through and updates the head and reader pointers as though the
replacement succeeded, which can corrupt the ring.

Treat only a negative counter as exhaustion and return the documented
-EBUSY error.

Cc: stable@vger.kernel.org
Fixes: 34e5b958bd ("tracing: Introduce simple_ring_buffer")
Link: https://patch.msgid.link/20260825-kernel-patch-1-v2-1-bb3461807a32@gmail.com
Assisted-by: LLM sparse
Reviewed-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Ivan Immanuel Shaji <ivanimmanuel1234@gmail.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2026-08-27 21:31:41 -04:00
Jérémy Jean
390f6bd858 tracing/user_events: Clear copied tracing state before fork duplication
dup_task_struct() copies user_event_mm from the parent into the child,
without grabbing a reference to it. user_event_mm_dup() should
replace it, but it leaves that copied pointer unmodified if
user_event_mm_alloc() fails.

When the child exits, user_event_mm_remove() decrements a reference
the child never owned, which ultimately frees user_event_mm, while
the parent still as a stale pointer to it. This creates a UAF, which
KASAN reports as:

    BUG: KASAN: slab-use-after-free in
    current_user_event_mm+0x51/0x1d0 Write of size 4 at addr
    ffff888005010d30 by task init/44

    Call Trace:
     <TASK>
     kasan_report+0xce/0x100
     kasan_check_range+0x10f/0x1e0
     current_user_event_mm+0x51/0x1d0
     user_events_ioctl+0x82e/0x15c0
     __x64_sys_ioctl+0x139/0x1c0
     do_syscall_64+0xce/0x450
     entry_SYSCALL_64_after_hwframe+0x77/0x7f

    Allocated by task 44:
     __kasan_kmalloc+0x8f/0xa0
     __kmalloc_cache_noprof+0x180/0x3a0
     user_event_mm_alloc+0x3c/0x1f0
     current_user_event_mm+0x88/0x1d0

    Freed by task 42:
     __kasan_slab_free+0x43/0x70
     kfree+0x13a/0x390
     process_one_work+0x696/0xf90
     worker_thread+0x420/0xba0

The fix simply clears the copied pointer before any possible failure.
In case of failure, the child then has nothing to free.

Cc: stable@vger.kernel.org
Fixes: 7235759084 ("tracing/user_events: Use remote writes for event enablement")
Link: https://patch.msgid.link/20260827184321.2964601-2-Jeremy.Jean@oss.cyber.gouv.fr
Assisted-by: Codex:gpt-5
Signed-off-by: Jérémy Jean <Jeremy.Jean@oss.cyber.gouv.fr>
Reviewed-by: Bradley Morgan <brads@mainlining.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2026-08-27 21:30:22 -04:00
Linus Torvalds
7cec13314d dma-mapping fix for Linux 7.3
- integer overflow fix for kernel cmdline parser for DMA contiguous
 initialization code (Alexander Graf)
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Merge tag 'dma-mapping-7.3-2026-08-27' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux

Pull dma-mapping fix from Marek Szyprowski:

 - integer overflow fix for kernel cmdline parser for DMA contiguous
   initialization code (Alexander Graf)

* tag 'dma-mapping-7.3-2026-08-27' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux:
  dma-contiguous: fix truncation of numa_cma / cma_pernuma sizes >= 2G
2026-08-27 12:14:19 -07:00
Linus Torvalds
18fbf5151d mm.git review status for linus..mm-stable
Everything:
 
 Total patches:       171
 Reviews/patch:       1.83
 Reviewed rate:       82%
 
 Excluding selftests:
 
 Total patches:       149
 Reviews/patch:       1.77
 Reviewed rate:       80%
 
 Excluding selftests and maple_tree:
 
 Total patches:       129
 Reviews/patch:       1.99
 Reviewed rate:       89%
 
 Summary of patch series in this merge:
 
 - "mm/rmap: index MAP_PRIVATE file-backed folios by anonymous pgoff"
   (Lorenzo Stoakes):
 
   Index MAP_PRIVATE file-backed folios by their anonymous page offset to
   resolve confusion around reverse mapping for zeroed and CoW'd
   file-backed memory.
 
   Use this new VMA anonymous page offset tracking to eliminate index
   conflicts and lay the foundation for scalable CoW performance
   improvements.
 
 - "promote mapped executable folios after first usage for MGLRU" (Baolin
   Wang):
 
   Make MGLRU's protection of mapped executable file folios more
   reliable.  Follow the classical LRU's logic, promoting mapped executable
   file folios after their first usage to give executable code a better
   chance to stay in memory and improve workload performance.
 
 - "mm: vmscan: fix node reclaim ignoring swappiness parameter" (Ridong Chen):
 
   Fix per-node proactive reclaim interface's ignoring the swappiness
   parameter when CONFIG_MEMCG is disabled by consolidating sc_swappiness()
   into a single function that checks proactive_swappiness regardless of
   kernel configuration.
 
 - "mm/vmscan: reduce lru_lock contention via vmstat-derived scan-balance
   cost" (Usama Arif):
 
   Reduce lru_lock contention in the reclaim path by deriving
   scan-balance costs from vmstat counters rather than lock-acquired
   producer updates.
 
   Read and decay these cost signals on the reclaim side under a
   dedicated per-lruvec lock, reducing total LRU lock wait time by over 60%
   without impacting scan throughput.
 
 - "zram: fix zram issues reported by sashiko" (Sergey Senozhatsky):
 
   Fix two low-risk zram bugs which Sashiko spotted in drive-by review.
 
 - "Honor XA_FLAGS_ACCOUNT in xas_split_alloc() and charge to folio's
   memcg" (Zi Yan):
 
   Fix xas_split_alloc() by enabling target folio memcg charging during
   splits and adding the missing __GFP_ACCOUNT flag for proper XArray node
   memory accounting.
 
 - "selftests/mm: use pattern matching in .gitignore" (Pratyush Mallick):
 
   Replace hardcoded binary names in selftests/mm/.gitignore with a
   generic pattern-matching rule to automatically ignore generated test
   files and avoid manual updates when adding new tests.
 
 - "mm/page_ext: remove pgdat_page_ext_init()" (Sang-Heon Jeon):
 
   Make the incompatibility between FLATMEM and NUMA explicit in
   mm/Kconfig and remove the unused pgdat_page_ext_init() function.
 
 - "zram: fix zstd error paths and add parameter validation" (Haoqin Huang):
 
   Clean up zram compression backends by removing redundant error
   cleanup, adding parameter and dictionary validation, auto-prefixing
   algorithm error logs, and resetting parameters prior to
   reinitialization.
 
 - "zram: fix stale scan bounds after reinitialization" (Longlong Xia):
 
   Prevent out-of-bounds slot accesses during concurrent zram resets by
   moving table scan bound calculations under dev_lock in writeback_store()
   and read_block_state().
 
 - "add anon mTHP collapse test cases" (Baolin Wang):
 
   Extend selftests helper functions to support arbitrary page orders and
   add new test cases and options for mTHP collapse in khugepaged.
 
 - "selftests/mm: Handle unsupported and transient test conditions"
   (Muhammad Usama Anjum):
 
   Update MM selftests to report a SKIP status instead of a failure when
   required kernel or filesystem features are unsupported, while adding
   retry logic for transient page migration errors.
 
 - "mm/zswap: Fixes and improves the zswap shrink" (Hao Jia):
 
   Fix the missing zswap global shrinker when CONFIG_MEMCG is disabled
   and extend shrink_memcg() to support batch writeback for improved
   writeback efficiency.
 
 - "alloc_tag: introduce IOCTL-based filtering for MAP" (Suren Baghdasaryan):
 
   Introduce an IOCTL-based binary interface for memory allocation
   profiling that enables kernel-side filtering before per-CPU counter
   aggregation.
 
   This eliminates the text-parsing overhead of /proc/allocinfo and
   provides up to a 20x speedup by transferring only filtered allocation
   data to userspace.
 
 - "better block swap batching and a different take on swap_ops v5"
   (Christoph Hellwig):
 
   Refactor block swap I/O to use swap_iocb for batching instead of
   single-bio requests and rebase the swap_ops interface, achieving faster
   swap throughput during kernel builds.
 
 - "mm: kmemleak: reduce transient false positives by confirming leaks"
   (Catalin Marinas):
 
   Reduce false-positive kmemleak reports by combining two kmemleak
   enhancements that add a second confirmation scan and a configurable
   minimum unreferenced scan count module parameter.
 
 - "mm: kmemleak: default min_unref_scans to 2 for verbose kernels"
   (Breno Leitao):
 
   Auto-scanning kernels can generate false-positive memory leak reports
   on single scans, so this patch defaults min_unref_scans to 2 when
   CONFIG_DEBUG_KMEMLEAK_VERBOSE is enabled to require a second confirming
   scan.
 
 - "swap_ops updates" (Christoph Hellwig):
 
   Batching I/O for synchronous swap devices causes performance
   regressions and filesystem-based swap suffers from double-indirection
   overhead.  This series resolves both issues by reintroducing per-folio
   writes for synchronous swap and allowing filesystems to directly export
   their own swap_ops.
 
 - "mm/khugepaged: several cleanups" (Nico Pache):
 
   khugepaged accumulated redundant state-checking patterns and outdated
   comments following mTHP integration.  Introduce dedicated helpers for
   PTE validation and event counting while refreshing the internal
   documentation.
 
 - "maple_tree: lock checking and clean ups" (Liam Howlett):
 
   Syzbot reports incorrectly blame memory management exit paths for
   locking bugs, maple tree erase operations risk allocation failures
   without gfp flags and internal documentation lacks clarity.
 
   Improve lock error detection, update docs, fix race and allocation
   edge cases and optimize erase allocations using a fallback to GFP_KERNEL
   | GFP_NOFAIL.
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Merge tag 'mm-stable-2026-08-26-15-22' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull more MM updates from Andrew Morton:

 - "mm/rmap: index MAP_PRIVATE file-backed folios by anonymous pgoff"
   (Lorenzo Stoakes)

   Index MAP_PRIVATE file-backed folios by their anonymous page offset
   to resolve confusion around reverse mapping for zeroed and CoW'd
   file-backed memory.

   Use this new VMA anonymous page offset tracking to eliminate index
   conflicts and lay the foundation for scalable CoW performance
   improvements.

 - "promote mapped executable folios after first usage for MGLRU"
   (Baolin Wang)

   Make MGLRU's protection of mapped executable file folios more
   reliable. Follow the classical LRU's logic, promoting mapped
   executable file folios after their first usage to give executable
   code a better chance to stay in memory and improve workload
   performance.

 - "mm: vmscan: fix node reclaim ignoring swappiness parameter" (Ridong
   Chen)

   Fix per-node proactive reclaim interface's ignoring the swappiness
   parameter when CONFIG_MEMCG is disabled by consolidating
   sc_swappiness() into a single function that checks
   proactive_swappiness regardless of kernel configuration.

 - "mm/vmscan: reduce lru_lock contention via vmstat-derived
   scan-balance cost" (Usama Arif)

   Reduce lru_lock contention in the reclaim path by deriving
   scan-balance costs from vmstat counters rather than lock-acquired
   producer updates.

   Read and decay these cost signals on the reclaim side under a
   dedicated per-lruvec lock, reducing total LRU lock wait time by over
   60% without impacting scan throughput.

 - "zram: fix zram issues reported by sashiko" (Sergey Senozhatsky)

   Fix two low-risk zram bugs which Sashiko spotted in drive-by review.

 - "Honor XA_FLAGS_ACCOUNT in xas_split_alloc() and charge to folio's
   memcg" (Zi Yan)

   Fix xas_split_alloc() by enabling target folio memcg charging during
   splits and adding the missing __GFP_ACCOUNT flag for proper XArray
   node memory accounting.

 - "selftests/mm: use pattern matching in .gitignore" (Pratyush Mallick)

   Replace hardcoded binary names in selftests/mm/.gitignore with a
   generic pattern-matching rule to automatically ignore generated test
   files and avoid manual updates when adding new tests.

 - "mm/page_ext: remove pgdat_page_ext_init()" (Sang-Heon Jeon)

   Make the incompatibility between FLATMEM and NUMA explicit in
   mm/Kconfig and remove the unused pgdat_page_ext_init() function.

 - "zram: fix zstd error paths and add parameter validation" (Haoqin
   Huang)

   Clean up zram compression backends by removing redundant error
   cleanup, adding parameter and dictionary validation, auto-prefixing
   algorithm error logs, and resetting parameters prior to
   reinitialization.

 - "zram: fix stale scan bounds after reinitialization" (Longlong Xia)

   Prevent out-of-bounds slot accesses during concurrent zram resets by
   moving table scan bound calculations under dev_lock in
   writeback_store() and read_block_state().

 - "add anon mTHP collapse test cases" (Baolin Wang)

   Extend selftests helper functions to support arbitrary page orders
   and add new test cases and options for mTHP collapse in khugepaged.

 - "selftests/mm: Handle unsupported and transient test conditions"
   (Muhammad Usama Anjum)

   Update MM selftests to report a SKIP status instead of a failure when
   required kernel or filesystem features are unsupported, while adding
   retry logic for transient page migration errors.

 - "mm/zswap: Fixes and improves the zswap shrink" (Hao Jia)

   Fix the missing zswap global shrinker when CONFIG_MEMCG is disabled
   and extend shrink_memcg() to support batch writeback for improved
   writeback efficiency.

 - "alloc_tag: introduce IOCTL-based filtering for MAP" (Suren
   Baghdasaryan)

   Introduce an IOCTL-based binary interface for memory allocation
   profiling that enables kernel-side filtering before per-CPU counter
   aggregation.

   This eliminates the text-parsing overhead of /proc/allocinfo and
   provides up to a 20x speedup by transferring only filtered allocation
   data to userspace.

 - "better block swap batching and a different take on swap_ops v5"
   (Christoph Hellwig)

   Refactor block swap I/O to use swap_iocb for batching instead of
   single-bio requests and rebase the swap_ops interface, achieving
   faster swap throughput during kernel builds.

 - "mm: kmemleak: reduce transient false positives by confirming leaks"
   (Catalin Marinas)

   Reduce false-positive kmemleak reports by combining two kmemleak
   enhancements that add a second confirmation scan and a configurable
   minimum unreferenced scan count module parameter.

 - "mm: kmemleak: default min_unref_scans to 2 for verbose kernels"
   (Breno Leitao)

   Auto-scanning kernels can generate false-positive memory leak reports
   on single scans, so this patch defaults min_unref_scans to 2 when
   CONFIG_DEBUG_KMEMLEAK_VERBOSE is enabled to require a second
   confirming scan.

 - "swap_ops updates" (Christoph Hellwig)

   Batching I/O for synchronous swap devices causes performance
   regressions and filesystem-based swap suffers from double-indirection
   overhead. This series resolves both issues by reintroducing per-folio
   writes for synchronous swap and allowing filesystems to directly
   export their own swap_ops.

 - "mm/khugepaged: several cleanups" (Nico Pache)

   khugepaged accumulated redundant state-checking patterns and outdated
   comments following mTHP integration. Introduce dedicated helpers for
   PTE validation and event counting while refreshing the internal
   documentation.

 - "maple_tree: lock checking and clean ups" (Liam Howlett)

   Syzbot reports incorrectly blame memory management exit paths for
   locking bugs, maple tree erase operations risk allocation failures
   without gfp flags and internal documentation lacks clarity.

   Improve lock error detection, update docs, fix race and allocation
   edge cases and optimize erase allocations using a fallback to
   GFP_KERNEL | GFP_NOFAIL.

* tag 'mm-stable-2026-08-26-15-22' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (172 commits)
  selftests/proc: make proc-maps-race work with READ_IMPLIES_EXEC
  memcg: move LRU size accounting on reparenting instead of copying it
  mm/vmscan: fix comment logic in balance_pgdat
  maple_tree: add helper mas_make_walkable()
  maple_tree: avoid extra gap calculation
  maple_tree: fix argument name in header
  maple_tree: change two GFP flags in tests
  maple_tree: document erase and allocations better
  maple_tree: avoid mas_erase() and mtree_erase() failures
  maple_tree: document that erase may use GFP_KERNEL for allocations
  maple_tree: catch race in mas_alloc_cyclic()
  maple_tree: add bulk parent set helper
  maple_tree: micro optimisation of mas_wr_store_type()
  maple_tree: optimise mas_wr_node_store() when not in rcu mode
  maple_tree: use prefetched value in mas_wr_store_type()
  maple_tree: clarify comments on mas_nomem()
  maple_tree: drop MAPLE_ALLOC_SLOTS
  maple_tree: drop dead code from mas_extend_spanning_null()
  maple_tree: documentation fix
  maple_tree: add write lock checking with lockdep sequence numbers
  ...
2026-08-27 09:17:06 -07:00
Linus Torvalds
73e3f07100 NFS client updates for Linux 7.3
Highlights include:
 
 Stable fixes:
 - SunRPC: Use-after-free fixes for the sunrpc client code
 - NFSv4: Delegation hash table leak
 - lockd: NULL dereference on lockowner allocation failure
 - SunRPC: Fix a handshake completion race in the TLS code
 - NFSv4.1/pNFS: Fix an error sign checking issue when deciding whether
   the layout is still in use, or can be returned.
 - NFSv4.1: Fix a layout segment leak in pnfs_layout_process()
 
 Other bugfixes:
 - SunRPC: Fix a missing NULL check in the rpcbind client
 - SunRPC: annotate shared socket callbacks with READ_ONCE/WRITE_ONCE
 - NFSv4: nfs_inode_set_delegation() error paths should return the delegation
 - NFSv4: Use clear_and_wake_up_bit() in nfs_clear_invalid_mapping() and
   the pNFS code.
 - NFSv4: Fix the nfs4_alloc_client() error paths to free the IDR
   allocation
 - NFS: fix folio dereference before NULL check in nfs_inode_remove_request()
 - NFS: Fix delayed delegation return
 - NFSv4: Fix another state manager race with umount
 - pNFS/blocklayout: Fix device leaks on parse failure
 - pNFS: Avoid cancelling in-flight I/O during a layout recall if the
   server doesn't require it
 - NFSv4/flexfiles: report cancelled I/O as a layout error
 - NFSv4/flexfiles: fix NULL dereference for NFSv4.0 data servers
 - NFSv4: Fix incorrect argument passed to nfs4_delete_lease()
 - NFSv3: Fix several symlink issues resulting from nfs_atomic_open_v23()
 - NFSv4.1: Fix an uninitialised variable issue in the callback code
 - NFSv4.2: fix LAYOUTSTATS send buffer exhaustion
 
 Features and cleanups:
 - NFSv4.2: Allow the server to specify that file data may not be cached
 - NFS/localio: optimise I/O submission when when not doing memory reclaim
 - NFS/localio: Remove duplicate wait code in nfs_local_commit
 - NFSv4/flexfiles: support loosely coupled NFSv4.x data servers
 - NFSv4/pnfs: key the data server cache on the NFS version
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Merge tag 'nfs-for-7.3-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs

Pull NFS client updates from Trond Myklebust:
 "Highlights include:

  Stable fixes:
   - Use-after-free fixes for the sunrpc client code
   - Delegation hash table leak
   - NULL dereference on lockowner allocation failure
   - Fix a handshake completion race in the TLS code
   - Fix an error sign checking issue when deciding whether the pNFS
     layout is still in use, or can be returned
   - Fix a layout segment leak in pnfs_layout_process()

  Other bugfixes:
   - Fix a missing NULL check in the rpcbind client
   - annotate shared socket callbacks with READ_ONCE/WRITE_ONCE
   - nfs_inode_set_delegation() error paths should return the delegation
   - Use clear_and_wake_up_bit() in nfs_clear_invalid_mapping() and the
     pNFS code.
   - Fix the nfs4_alloc_client() error paths to free the IDR allocation
   - fix folio dereference before NULL check in
     nfs_inode_remove_request()
   - Fix delayed delegation return
   - Fix another state manager race with umount
   - Fix device leaks on parse failure
   - Avoid cancelling in-flight I/O during a layout recall if the server
     doesn't require it
   - flexfiles: report cancelled I/O as a layout error
   - flexfiles: fix NULL dereference for NFSv4.0 data servers
   - Fix incorrect argument passed to nfs4_delete_lease()
   - Fix several symlink issues resulting from nfs_atomic_open_v23()
   - Fix an uninitialised variable issue in the NFSv4.1 callback code
   - fix LAYOUTSTATS send buffer exhaustion

  Features and cleanups:
   - NFSv4.2: Allow the server to specify that file data may not be cached
   - localio: optimise I/O submission when when not doing memory reclaim
   - localio: Remove duplicate wait code in nfs_local_commit
   - flexfiles: support loosely coupled NFSv4.x data servers
   - pNFS: key the data server cache on the NFS version"

* tag 'nfs-for-7.3-1' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: (33 commits)
  NFSv4.1: fix layout segment leak on the pnfs_layout_process() forget path
  NFSv4/pnfs: key the data server cache on the NFS version
  NFSv4.2: fix LAYOUTSTATS send buffer exhaustion
  pNFS: Fix EBUSY check in pnfs_layout_need_return
  NFSv4.1: zero referring call lists before decoding
  nfs: fix ENXIO on O_CREAT open of existing symlink over NFSv3
  SUNRPC: wait for in-flight client TLS handshake callback
  NFSv4: Fix incorrect argument passed to nfs4_delete_lease() in nfs4_add_lease()
  lockd: fix NULL dereference on lockowner allocation failure
  NFS: fix delegation_hash_table leak when nfs4_server_common_setup() fails
  NFSv4/flexfiles: support loosely coupled data servers
  NFSv4/flexfiles: fix NULL dereference for NFSv4.0 data servers
  NFSv4: pin the superblock for active state owners
  sunrpc: fix use-after-free in __rpc_clnt_handle_event and __rpc_clnt_remove_pipedir
  NFS/localio: issue commit inline when not in a memory-reclaim context
  NFS/localio: remove dead FLUSH_SYNC handling from nfs_local_commit
  NFS/localio: issue IO inline when not in a memory-reclaim context
  NFS: Fix delayed delegation return list handling
  NFS: Verify symlink inode before caching target
  NFS: fix folio dereference before NULL check in nfs_inode_remove_request()
  ...
2026-08-26 15:09:21 -07:00
Linus Torvalds
85671b807f More power management updates for 7.3-rc1
- Fix a kernel panic during PMU unbind in the intel_rapl power capping
    driver and sign-extend the PMU delta on counter wraparound in it to
    avoid misreporting energy (Sumeet Pawnikar and Yifan Li)
 
  - Unblock runtime PM when device prepare fails that was not done by
    mistake (Shibo Zhu)
 
  - Fix possible rate limit overflow on 32-bit systems in the schedutil
    cpufreq governor (Hui Su)
 
  - Consolidate HWP P-states initialization in the intel_pstate cpufreq
    driver and make that driver avoid using the DESIRED_PERF HWP hint
    when the Dynamic Efficiency Control (DEC) is enabled in the processor
    to avoid inconsistent behavior (Rafael Wysocki)
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Merge tag 'pm-7.3-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm

Pull more power management updates from Rafael Wysocki:
 "These fix two issues in the intel_rapl power capping driver, fix a
  potential issue in the schedutil cpufreq governor on 32-bit systems,
  fix a runtime PM issue related to failing system suspend, and update
  the intel_pstate cpufreq driver:

   - Fix a kernel panic during PMU unbind in the intel_rapl power
     capping driver and sign-extend the PMU delta on counter wraparound
     in it to avoid misreporting energy (Sumeet Pawnikar and Yifan Li)

   - Unblock runtime PM when device prepare fails that was not done by
     mistake (Shibo Zhu)

   - Fix possible rate limit overflow on 32-bit systems in the schedutil
     cpufreq governor (Hui Su)

   - Consolidate HWP P-states initialization in the intel_pstate cpufreq
     driver and make that driver avoid using the DESIRED_PERF HWP hint
     when the Dynamic Efficiency Control (DEC) is enabled in the
     processor to avoid inconsistent behavior (Rafael Wysocki)"

* tag 'pm-7.3-rc1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  powercap: intel_rapl: Fix kernel panic during PMU unbind
  PM: sleep: Unblock runtime PM when device prepare fails
  powercap: intel_rapl: Sign-extend the PMU delta on counter wraparound
  cpufreq: intel_pstate: Avoid using DESIRED_PERF when DEC is enabled
  cpufreq: intel_pstate: Consolidate HWP P-states initialization
  cpufreq: schedutil: Fix rate limit overflow
2026-08-26 14:13:26 -07:00
Rafael J. Wysocki
76854b339b Merge branches 'pm-cpufreq' and 'pm-sleep'
Merge additional cpufreq updates and one update related to system sleep
for 7.3-rc1:

 - Unblock runtime PM when device prepare fails that was not done by
   mistake (Shibo Zhu)

 - Fix possible rate limit overflow on 32-bit systems in the schedutil
   cpufreq governor (Hui Su)

 - Consolidate HWP P-states initialization in the intel_pstate cpufreq
   driver and make that driver avoid using the DESIRED_PERF HWP hint
   when the Dynamic Efficiency Control (DEC) is enabled in the processor
   to avoid inconsistent behavior (Rafael Wysocki)

* pm-cpufreq:
  cpufreq: intel_pstate: Avoid using DESIRED_PERF when DEC is enabled
  cpufreq: intel_pstate: Consolidate HWP P-states initialization
  cpufreq: schedutil: Fix rate limit overflow

* pm-sleep:
  PM: sleep: Unblock runtime PM when device prepare fails
2026-08-26 19:49:23 +02:00
Liam R. Howlett (Oracle)
8f21098431 locking/lockdep: add sequence counter to held_lock
Add an 8 bit small sequence counter to the held_lock struct to detect if
the lock as been dropped and reacquired.  This is useful when a data
structure depends on a constant locking context, but is not able to detect
locking and unlocking of the lock through its own API.

Since the __lock_unpin_lock() will no longer detect underflow by casting
the unsigned int to a signed int, update the casting code to use a temp
variable for calculations using a signed int.

Link: https://lore.kernel.org/20260821192627.4085470-3-liam@infradead.org
Signed-off-by: Liam R. Howlett (Oracle) <liam@infradead.org>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Will Deacon <will@kernel.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Waiman Long <longman@redhat.com>
Link: https://lore.kernel.org/all/h3tpnj5kzcrxms5picmimtkpg4aypcpip5wbd6bt2rpdj5k7eb@nhtzs3lefrkq/
Cc: Breno Leitao <leitao@debian.org>
Cc: Chris Mason <clm@meta.com>
Cc: Chuck Lever <cel@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Joe Perches <joe@perches.com>
Cc: Rik van Riel <riel@surriel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-08-24 18:43:28 -07:00
Lorenzo Stoakes (ARM)
51943a18ad mm: provide vma_[flags_]is_cow_mapping() and remove is_cow_mapping()
All remaining callers of is_cow_mapping() are invoking it in the form of
is_cow_mapping(vma->vm_flags) or an indirected version of this.

Therefore, provide a helper - vma_is_cow_mapping() to directly test the
VMA.

Additionally provide a new helper vma_flags_is_cow_mapping() which
performs the check using the new vma_flags_t type, and share this logic
between vma_is_cow_mapping() and vma_desc_is_cow_mapping().

With these changes, no callers of is_cow_mapping() remain, so remove it.

Also update the userland VMA tests to reflect the change.

No functional change intended.

[akpm@linux-foundation.org: fix kerneldoc comment typo, per Lorenzo]
  Link: https://lore.kernel.org/aob1goSSPH6sTN9y@gremlin
Link: https://lore.kernel.org/20260813-b4-scalable-cow-virt-pgoff-v5-2-c21581c0c3c8@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Deucher <alexander.deucher@amd.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <baoquan.he@linux.dev>
Cc: Barry Song <baohua@kernel.org>
Cc: Boris Brezillon <boris.brezillon@collabora.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christan König <christian.koenig@amd.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Dave Airlie <airlied@gmail.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Gregory Price (Meta) <gourry@gourry.net>
Cc: Harry Yoo <harry@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Huang Ray <Ray.Huang@amd.com>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@linaro.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Janosch Frank <frankja@linux.ibm.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Liviu Dudau <liviu.dudau@arm.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Namhyung kim <namhyung@kernel.org>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Steven Price <steven.price@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Thomas Zimemrmann <tzimmermann@suse.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-08-24 18:42:50 -07:00
Linus Torvalds
2f43193b88 dma-mapping updates for Linux 7.3:
- swiotlb: added new configuration option for the default pool size
 (Jagadeesh Pagadala) and reduced overhead for high watermark tracking
 (chenhuguanshen)
 
 - minor code cleanups and improvements (Vova Sharaienko, Honglei Huang
 and Marek Szyprowski)
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mergetag object 04a19b35dc
 type commit
 tag dma-mapping-7.3-2026-08-24-2
 tagger Marek Szyprowski <m.szyprowski@samsung.com> 1787582472 +0200
 
 second dma-mapping update for Linux 7.3:
 
 - important dma-mapping update for confidential-computing, which adds
 proper tracking of the shared DMA state through direct, pool and swiotlb
 paths (Aneesh Kumar K.V)
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Merge tags 'dma-mapping-7.3-2026-08-24' and 'dma-mapping-7.3-2026-08-24-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux

Pull dma-mapping updates from Marek Szyprowski:

 - swiotlb:
     - new configuration option for the default pool size
       (Jagadeesh Pagadala)
     - reduce overhead for high watermark tracking (chenhuguanshen)

 - minor code cleanups and improvements (Vova Sharaienko, Honglei Huang
   and Marek Szyprowski)

 - add proper tracking of the shared DMA state through direct, pool and
   swiotlb paths (Aneesh Kumar K.V)

   This is important for confidential-computing

* tag 'dma-mapping-7.3-2026-08-24' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux:
  dma/swiotlb: decouple high watermark tracking from CONFIG_DEBUG_FS
  MAINTAINERS: update tree for DMA MAPPING HELPERS
  dma/swiotlb: introduce Kconfig option for compile-time default pool size
  dma-direct: Improve readability of the dma_direct_map_sg() for P2PDMA case
  iommu/dma: simplify dma_iova_destroy() and drop the free_iova helper
  dma-coherent: use KiB in DMA allocation logs
  dma-coherent: fix spacing coding style issue

* tag 'dma-mapping-7.3-2026-08-24-2' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux: (23 commits)
  swiotlb: remove unused SWIOTLB_FORCE flag
  dma: swiotlb: handle set_memory_decrypted() failures
  dma: swiotlb: free dynamic pools from process context
  dma-direct: rename ret to cpu_addr in alloc helpers
  dma-direct: select DMA address encoding from __DMA_ATTR_ALLOC_CC_SHARED
  dma-direct: set decrypted flag for remapped DMA allocations
  dma-direct: make dma_direct_map_phys() honor DMA_ATTR_CC_SHARED
  dma-direct: Move dma_direct_map_phys() to dma/direct.c
  dma-direct: pass attrs to dma_capable() for DMA_ATTR_CC_SHARED checks
  dma-mapping: make dma_pgprot() honor __DMA_ATTR_ALLOC_CC_SHARED
  dma: swiotlb: track pool encryption state and honor DMA_ATTR_CC_SHARED
  dma: swiotlb: pass mapping attributes by reference
  dma-pool: track decrypted atomic pools and select them via attrs
  dma-direct: use __DMA_ATTR_ALLOC_CC_SHARED in alloc/free paths
  dma-mapping: Add internal shared allocation attribute
  coco: arm64: s390: powerpc: Mark secure guests with CC_ATTR_GUEST_MEM_ENCRYPT
  dma-direct: swiotlb: handle swiotlb alloc/free outside __dma_direct_alloc_pages
  s390: Expose protected virtualization through cc_platform_has()
  swiotlb: Preserve allocation virtual address for dynamic pools
  dma: free atomic pool pages by physical address
  ...
2026-08-24 11:35:46 -07:00
Alexander Graf
1476cca098 dma-contiguous: fix truncation of numa_cma / cma_pernuma sizes >= 2G
numa_cma=0:4G reserves nothing at all. dma_numa_cma_reserve() copies the
requested size into a local int before handing it to
cma_declare_contiguous_nid(), so 0x100000000 truncates to zero and the
loop skips the node silently. Both parameters are documented in
kernel-parameters.txt as nn[MG], so that is the syntax the documentation
invites.

Which bits survive decides what a request turns into: 4G, 8G and 16G
reserve nothing, 2G, 3G and 6G sign-extend into a size the allocator
rejects with a warning, and 5G quietly reserves 1G.

It reaches further than those parameters. On a CMA_SIZE_PERNUMA kernel
with no per-node parameter, dma_numa_cma_reserve() takes the per-node
size from the default area, so a plain cma=4G on a multi-node machine
feeds that size through the same local and loses every per-node area.

numa_cma_size[] and pernuma_size_bytes are both phys_addr_t, so use it
for the local too, and give early_numa_cma() separate variables for the
node id and the size while in there.

Fixes: d5cae2261b ("dma-contiguous: simplify numa cma area handling")
Cc: stable@vger.kernel.org
Assisted-by: Kiro:claude-opus-5
Signed-off-by: Alexander Graf <graf@amazon.com>
Reviewed-by: Feng Tang <feng.tang@linux.alibaba.com>
Link: https://lore.kernel.org/r/20260821224252.70640-1-graf@amazon.com
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
2026-08-24 15:40:07 +02:00
Peter Zijlstra
46094a7708 locking: Revert switching guards to _irq_{disable,enable}()
Revert commit 1b08668748 ("locking: Switch to _irq_{disable,enable}()
variants in cleanup guards").

While the guards are properly nested, not all wrapped code is nice, as already
highlighted by that fair.c hunk.

Syzbot found another instance of this pattern in posix_timer_delete(), which
does spin_unlock_irq()+spin_lock_irq() inside scoped_guard(spinlock_irq).
Combined with this patch, that goes sideways most spectacular.

Undo this until we've developed stronger tools / debug for such issues.

Fixes: 1b08668748 ("locking: Switch to _irq_{disable,enable}() variants in cleanup guards")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://patch.msgid.link/20260824105523.GA4121620%40noisy.programming.kicks-ass.net
2026-08-24 12:58:54 +02:00
Linus Torvalds
0a0d1d55da smp_call_function() torture-test updates:
* Count single_rpc offline failures in statistics output.
  * Make invoker threads actually wait for all threads to start.
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Merge tag 'scftorture.2026.08.18a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux

Pull smp_call_function() torture-test updates from Paul McKenney:

 - Count single_rpc offline failures in statistics output

 - Make invoker threads actually wait for all threads to start

* tag 'scftorture.2026.08.18a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux:
  scftorture: Make invoker threads actually wait for all threads to start
  scftorture: Count single_rpc offline failures in statistics output
2026-08-23 19:28:04 -07:00
Linus Torvalds
83684c4e4d RCU updates:
Make expedited grace periods expedite normal RCU callbacks
 
 Miscellaneous fixes:
  * Improve diagnostic output with character task states.
  * Mark accesses to inform KCSAN of concurrency design.
  * Move from kmalloc() to kmalloc_obj().
  * Documentation updates.
  * Improve handling of RCU deferred quiescent states.
  * Clean up unused function arguments and structure fields.
  * Reduce show_rcu_gp_kthreads() stack space.
 
 Tasks RCU updates:
  * Clean up after SRCU re-implementation of Tasks Trace RCU.
  * Mark accesses to inform KCSAN of concurrency design.
  * Add ->lazy_timer status to diagnostic output.
  * Remove an unnecessary memory barrier.
  * Fix a data race, courtesy of KCSAN.
  * Documentation updates.
  * Convert cond_resched_tasks_rcu_qs() from macro to static inline
    function.
 
 SRCU updates:
  * Add Rust helpers for SRCU.
  * Avoid losing queued work at cleanup_srcu_struct() time.
 
 Torture-test updates:
  * Preparation work for immediate RCU priority deboosting.
  * Test RCU readers from real interrupt handlers (as opposed to softirq).
  * Simplify code through use of cpumask_next_wrap().
  * Improve diagnostic output with character task states.
  * Add rcutorture.nwriters parameter to allow lightweight stall testing,
    and rcutorture.stall_only to make doing so easier.
  * Test an RCU Tasks Trace grace period implying an RCU grace period.
  * Make RCU Tasks Trace torturing track reader batches.
  * Fix a data race, courtesy of KCSAN.
  * Plug a shuffle_tmp_mask memory leak on kthread spawn failure.
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Merge tag 'rcu.2026.08.18a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux

Pull RCU updates from Paul McKenney:
 "Make expedited grace periods expedite normal RCU callbacks

  Miscellaneous fixes:
   - Improve diagnostic output with character task states
   - Mark accesses to inform KCSAN of concurrency design
   - Move from kmalloc() to kmalloc_obj()
   - Documentation updates
   - Improve handling of RCU deferred quiescent states
   - Clean up unused function arguments and structure fields
   - Reduce show_rcu_gp_kthreads() stack space

  Tasks RCU updates:
   - Clean up after SRCU re-implementation of Tasks Trace RCU
   - Mark accesses to inform KCSAN of concurrency design
   - Add ->lazy_timer status to diagnostic output
   - Remove an unnecessary memory barrier
   - Fix a data race, courtesy of KCSAN
   - Documentation updates
   - Convert cond_resched_tasks_rcu_qs() from macro to static inline
     function

  SRCU updates:
   - Add Rust helpers for SRCU
   - Avoid losing queued work at cleanup_srcu_struct() time

  Torture-test updates:
   - Preparation work for immediate RCU priority deboosting
   - Test RCU readers from real interrupt handlers (as opposed to
     softirq)
   - Simplify code through use of cpumask_next_wrap()
   - Improve diagnostic output with character task states
   - Add rcutorture.nwriters parameter to allow lightweight stall
     testing, and rcutorture.stall_only to make doing so easier
   - Test an RCU Tasks Trace grace period implying an RCU grace period
   - Make RCU Tasks Trace torturing track reader batches
   - Fix a data race, courtesy of KCSAN
   - Plug a shuffle_tmp_mask memory leak on kthread spawn failure"

* tag 'rcu.2026.08.18a' of git://git.kernel.org/pub/scm/linux/kernel/git/rcu/linux: (59 commits)
  rcu: Add closing parenthesis in comment in rcu_read_unlock_strict()
  rcutorture: Make {,s}rcu_read_delay() better handle forward-progress testing
  rcutorture: Announce declining to forward-progress test
  torture: Don't leak shuffle_tmp_mask when shuffler kthread fails to start
  rcutorture: Use this_cpu_inc() for rcu_torture_count[] and rcu_torture_batch[]
  rcutorture: Make RCU Tasks Trace track Reader Batches
  rcutorture: Test RCU Tasks Trace GP implying RCU GP
  rcutorture: Add a stall_only module parameter
  rcutorture: Add nwriters module parameter
  rcutorture: Use task_state_to_char() for task-state reporting
  rcutorture: Use cpumask_next_wrap() in rcu_torture_preempt()
  rcutorture: Test RCU readers from hardware interrupt handlers
  rcutorture: Check for immediate deboosting at reader end
  srcu: Queue sdp->work when the delay timer is successfully deleted
  rcu-tasks: Convert cond_resched_tasks_rcu_qs() to static inline
  rcu-tasks: Fix some comments for call_rcu_tasks() and call_rcu_tasks_rude()
  rcu-tasks: Rename tasks_rcu_exit_srcu_stall_timer to tasks_rcu_exit_stall_timer
  rcu: Mark interrupts-enabled accesses to rdp->cpu_no_qs.s
  rcu: Reduce stack usage in show_rcu_gp_kthreads()
  rcu: Mark accesses to ->rcu_urgent_qs and ->rcu_need_heavy_qs
  ...
2026-08-23 18:00:22 -07:00