Commit Graph

49039 Commits (378b7708194fff77c9020392067329931c3fcc04)

Author SHA1 Message Date
Menglong Dong 378b770819 sched: Make migrate_{en,dis}able() inline
For now, migrate_enable and migrate_disable are global, which makes them
become hotspots in some case. Take BPF for example, the function calling
to migrate_enable and migrate_disable in BPF trampoline can introduce
significant overhead, and following is the 'perf top' of FENTRY's
benchmark (./tools/testing/selftests/bpf/bench trig-fentry):

  54.63% bpf_prog_2dcccf652aac1793_bench_trigger_fentry [k]
                 bpf_prog_2dcccf652aac1793_bench_trigger_fentry
  10.43% [kernel] [k] migrate_enable
  10.07% bpf_trampoline_6442517037 [k] bpf_trampoline_6442517037
  8.06% [kernel] [k] __bpf_prog_exit_recur
  4.11% libc.so.6 [.] syscall
  2.15% [kernel] [k] entry_SYSCALL_64
  1.48% [kernel] [k] memchr_inv
  1.32% [kernel] [k] fput
  1.16% [kernel] [k] _copy_to_user
  0.73% [kernel] [k] bpf_prog_test_run_raw_tp

So in this commit, we make migrate_enable/migrate_disable inline to obtain
better performance. The struct rq is defined internally in
kernel/sched/sched.h, and the field "nr_pinned" is accessed in
migrate_enable/migrate_disable, which makes it hard to make them inline.

Alexei Starovoitov suggests to generate the offset of "nr_pinned" in [1],
so we can define the migrate_enable/migrate_disable in
include/linux/sched.h and access "this_rq()->nr_pinned" with
"(void *)this_rq() + RQ_nr_pinned".

The offset of "nr_pinned" is generated in include/generated/rq-offsets.h
by kernel/sched/rq-offsets.c.

Generally speaking, we move the definition of migrate_enable and
migrate_disable to include/linux/sched.h from kernel/sched/core.c. The
calling to __set_cpus_allowed_ptr() is leaved in ___migrate_enable().

The "struct rq" is not available in include/linux/sched.h, so we can't
access the "runqueues" with this_cpu_ptr(), as the compilation will fail
in this_cpu_ptr() -> raw_cpu_ptr() -> __verify_pcpu_ptr():
  typeof((ptr) + 0)

So we introduce the this_rq_raw() and access the runqueues with
arch_raw_cpu_ptr/PERCPU_PTR directly.

The variable "runqueues" is not visible in the kernel modules, and export
it is not a good idea. As Peter Zijlstra advised in [2], we define and
export migrate_enable/migrate_disable in kernel/sched/core.c too, and use
them for the modules.

Before this patch, the performance of BPF FENTRY is:

  fentry         :  113.030 ± 0.149M/s
  fentry         :  112.501 ± 0.187M/s
  fentry         :  112.828 ± 0.267M/s
  fentry         :  115.287 ± 0.241M/s

After this patch, the performance of BPF FENTRY increases to:

  fentry         :  143.644 ± 0.670M/s
  fentry         :  149.764 ± 0.362M/s
  fentry         :  149.642 ± 0.156M/s
  fentry         :  145.263 ± 0.221M/s

Signed-off-by: Menglong Dong <dongml2@chinatelecom.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/bpf/CAADnVQ+5sEDKHdsJY5ZsfGDO_1SEhhQWHrt2SMBG5SYyQ+jt7w@mail.gmail.com/ [1]
Link: https://lore.kernel.org/all/20250819123214.GH4067720@noisy.programming.kicks-ass.net/ [2]
2025-09-25 09:57:16 +02:00
Aaron Lu 0d4eaf8caf sched/fair: Do not balance task to a throttled cfs_rq
When doing load balance and the target cfs_rq is in throttled hierarchy,
whether to allow balancing there is a question.

The good side to allow balancing is: if the target CPU is idle or less
loaded and the being balanced task is holding some kernel resources,
then it seems a good idea to balance the task there and let the task get
the CPU earlier and release kernel resources sooner. The bad part is, if
the task is not holding any kernel resources, then the balance seems not
that useful.

While theoretically it's debatable, a performance test[0] which involves
200 cgroups and each cgroup runs hackbench(20 sender, 20 receiver) in
pipe mode showed a performance degradation on AMD Genoa when allowing
load balance to throttled cfs_rq. Analysis[1] showed hackbench doesn't
like task migration across LLC boundary. For this reason, add a check in
can_migrate_task() to forbid balancing to a cfs_rq that is in throttled
hierarchy. This reduced task migration a lot and performance restored.

[0]: https://lore.kernel.org/lkml/20250822110701.GB289@bytedance/
[1]: https://lore.kernel.org/lkml/20250903101102.GB42@bytedance/

Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
2025-09-15 09:38:38 +02:00
Aaron Lu 253b3f5872 sched/fair: Do not special case tasks in throttled hierarchy
With the introduction of task based throttle model, task in a throttled
hierarchy is allowed to continue to run till it gets throttled on its
ret2user path.

For this reason, remove those throttled_hierarchy() checks in the
following functions so that those tasks can get their turn as normal
tasks: dequeue_entities(), check_preempt_wakeup_fair() and
yield_to_task_fair().

The benefit of doing it this way is: if those tasks gets the chance to
run earlier and if they hold any kernel resources, they can release
those resources earlier. The downside is, if they don't hold any kernel
resouces, all they can do is to throttle themselves on their way back to
user space so the favor to let them run seems not that useful and for
check_preempt_wakeup_fair(), that favor may be bad for curr.

K Prateek Nayak pointed out prio_changed_fair() can send a throttled
task to check_preempt_wakeup_fair(), further tests showed the affinity
change path from move_queued_task() can also send a throttled task to
check_preempt_wakeup_fair(), that's why the check of task_is_throttled()
in that function.

Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2025-09-15 09:38:37 +02:00
Aaron Lu fcd394866e sched/fair: update_cfs_group() for throttled cfs_rqs
With task based throttle model, tasks in a throttled hierarchy are
allowed to continue to run if they are running in kernel mode. For this
reason, PELT clock is not stopped for these cfs_rqs in throttled
hierarchy when they still have tasks running or queued.

Since PELT clock is not stopped, whether to allow update_cfs_group()
doing its job for cfs_rqs which are in throttled hierarchy but still
have tasks running/queued is a question.

The good side is, continue to run update_cfs_group() can get these
cfs_rq entities with an up2date weight and that up2date weight can be
useful to derive an accurate load for the CPU as well as ensure fairness
if multiple tasks of different cgroups are running on the same CPU.
OTOH, as Benjamin Segall pointed: when unthrottle comes around the most
likely correct distribution is the distribution we had at the time of
throttle.

In reality, either way may not matter that much if tasks in throttled
hierarchy don't run in kernel mode for too long. But in case that
happens, let these cfs_rq entities have an up2date weight seems a good
thing to do.

Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2025-09-15 09:38:37 +02:00
Aaron Lu fe8d238e64 sched/fair: Propagate load for throttled cfs_rq
Before task based throttle model, propagating load will stop at a
throttled cfs_rq and that propagate will happen on unthrottle time by
update_load_avg().

Now that there is no update_load_avg() on unthrottle for throttled
cfs_rq and all load tracking is done by task related operations, let the
propagate happen immediately.

While at it, add a comment to explain why cfs_rqs that are not affected
by throttle have to be added to leaf cfs_rq list in
propagate_entity_cfs_rq() per my understanding of commit 0258bdfaff
("sched/fair: Fix unfairness caused by missing load decay").

Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>
2025-09-15 09:38:37 +02:00
Aaron Lu 5b726e9bf9 sched/fair: Get rid of throttled_lb_pair()
Now that throttled tasks are dequeued and can not stay on rq's cfs_tasks
list, there is no need to take special care of these throttled tasks
anymore in load balance.

Suggested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Valentin Schneider <vschneid@redhat.com>
Tested-by: Matteo Martelli <matteo.martelli@codethink.co.uk>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20250829081120.806-6-ziqianlu@bytedance.com
2025-09-03 10:03:14 +02:00
Aaron Lu eb962f251f sched/fair: Task based throttle time accounting
With task based throttle model, the previous way to check cfs_rq's
nr_queued to decide if throttled time should be accounted doesn't work
as expected, e.g. when a cfs_rq which has a single task is throttled,
that task could later block in kernel mode instead of being dequeued on
limbo list and accounting this as throttled time is not accurate.

Rework throttle time accounting for a cfs_rq as follows:
- start accounting when the first task gets throttled in its hierarchy;
- stop accounting on unthrottle.

Note that there will be a time gap between when a cfs_rq is throttled
and when a task in its hierarchy is actually throttled. This accounting
mechanism only starts accounting in the latter case.

Suggested-by: Chengming Zhou <chengming.zhou@linux.dev> # accounting mechanism
Co-developed-by: K Prateek Nayak <kprateek.nayak@amd.com> # simplify implementation
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Valentin Schneider <vschneid@redhat.com>
Tested-by: Matteo Martelli <matteo.martelli@codethink.co.uk>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20250829081120.806-5-ziqianlu@bytedance.com
2025-09-03 10:03:14 +02:00
Valentin Schneider e1fad12dcb sched/fair: Switch to task based throttle model
In current throttle model, when a cfs_rq is throttled, its entity will
be dequeued from cpu's rq, making tasks attached to it not able to run,
thus achiveing the throttle target.

This has a drawback though: assume a task is a reader of percpu_rwsem
and is waiting. When it gets woken, it can not run till its task group's
next period comes, which can be a relatively long time. Waiting writer
will have to wait longer due to this and it also makes further reader
build up and eventually trigger task hung.

To improve this situation, change the throttle model to task based, i.e.
when a cfs_rq is throttled, record its throttled status but do not remove
it from cpu's rq. Instead, for tasks that belong to this cfs_rq, when
they get picked, add a task work to them so that when they return
to user, they can be dequeued there. In this way, tasks throttled will
not hold any kernel resources. And on unthrottle, enqueue back those
tasks so they can continue to run.

Throttled cfs_rq's PELT clock is handled differently now: previously the
cfs_rq's PELT clock is stopped once it entered throttled state but since
now tasks(in kernel mode) can continue to run, change the behaviour to
stop PELT clock when the throttled cfs_rq has no tasks left.

Suggested-by: Chengming Zhou <chengming.zhou@linux.dev> # tag on pick
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Valentin Schneider <vschneid@redhat.com>
Tested-by: Chen Yu <yu.c.chen@intel.com>
Tested-by: Matteo Martelli <matteo.martelli@codethink.co.uk>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20250829081120.806-4-ziqianlu@bytedance.com
2025-09-03 10:03:14 +02:00
Valentin Schneider 7fc2d14392 sched/fair: Implement throttle task work and related helpers
Implement throttle_cfs_rq_work() task work which gets executed on task's
ret2user path where the task is dequeued and marked as throttled.

Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>
Tested-by: Valentin Schneider <vschneid@redhat.com>
Tested-by: Matteo Martelli <matteo.martelli@codethink.co.uk>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20250829081120.806-3-ziqianlu@bytedance.com
2025-09-03 10:03:13 +02:00
Valentin Schneider 2cd571245b sched/fair: Add related data structure for task based throttle
Add related data structures for this new throttle functionality.

Tesed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Valentin Schneider <vschneid@redhat.com>
Signed-off-by: Aaron Lu <ziqianlu@bytedance.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Chengming Zhou <chengming.zhou@linux.dev>
Tested-by: Valentin Schneider <vschneid@redhat.com>
Tested-by: Matteo Martelli <matteo.martelli@codethink.co.uk>
Link: https://lore.kernel.org/r/20250829081120.806-2-ziqianlu@bytedance.com
2025-09-03 10:03:13 +02:00
Peter Zijlstra 91c614f09a sched: Move STDL_INIT() functions out-of-line
Since all these functions are address-taken in SDTL_INIT() and called
indirectly, it doesn't really make sense for them to be inline.

Suggested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
2025-09-03 10:03:13 +02:00
Peter Zijlstra 661f951e37 sched/fair: Get rid of sched_domains_curr_level hack for tl->cpumask()
Leon [1] and Vinicius [2] noted a topology_span_sane() warning during
their testing starting from v6.16-rc1. Debug that followed pointed to
the tl->mask() for the NODE domain being incorrectly resolved to that of
the highest NUMA domain.

tl->mask() for NODE is set to the sd_numa_mask() which depends on the
global "sched_domains_curr_level" hack. "sched_domains_curr_level" is
set to the "tl->numa_level" during tl traversal in build_sched_domains()
calling sd_init() but was not reset before topology_span_sane().

Since "tl->numa_level" still reflected the old value from
build_sched_domains(), topology_span_sane() for the NODE domain trips
when the span of the last NUMA domain overlaps.

Instead of replicating the "sched_domains_curr_level" hack, get rid of
it entirely and instead, pass the entire "sched_domain_topology_level"
object to tl->cpumask() function to prevent such mishap in the future.

sd_numa_mask() now directly references "tl->numa_level" instead of
relying on the global "sched_domains_curr_level" hack to index into
sched_domains_numa_masks[].

The original warning was reproducible on the following NUMA topology
reported by Leon:

    $ sudo numactl -H
    available: 5 nodes (0-4)
    node 0 cpus: 0 1
    node 0 size: 2927 MB
    node 0 free: 1603 MB
    node 1 cpus: 2 3
    node 1 size: 3023 MB
    node 1 free: 3008 MB
    node 2 cpus: 4 5
    node 2 size: 3023 MB
    node 2 free: 3007 MB
    node 3 cpus: 6 7
    node 3 size: 3023 MB
    node 3 free: 3002 MB
    node 4 cpus: 8 9
    node 4 size: 3022 MB
    node 4 free: 2718 MB
    node distances:
    node   0   1   2   3   4
      0:  10  39  38  37  36
      1:  39  10  38  37  36
      2:  38  38  10  37  36
      3:  37  37  37  10  36
      4:  36  36  36  36  10

The above topology can be mimicked using the following QEMU cmd that was
used to reproduce the warning and test the fix:

     sudo qemu-system-x86_64 -enable-kvm -cpu host \
     -m 20G -smp cpus=10,sockets=10 -machine q35 \
     -object memory-backend-ram,size=4G,id=m0 \
     -object memory-backend-ram,size=4G,id=m1 \
     -object memory-backend-ram,size=4G,id=m2 \
     -object memory-backend-ram,size=4G,id=m3 \
     -object memory-backend-ram,size=4G,id=m4 \
     -numa node,cpus=0-1,memdev=m0,nodeid=0 \
     -numa node,cpus=2-3,memdev=m1,nodeid=1 \
     -numa node,cpus=4-5,memdev=m2,nodeid=2 \
     -numa node,cpus=6-7,memdev=m3,nodeid=3 \
     -numa node,cpus=8-9,memdev=m4,nodeid=4 \
     -numa dist,src=0,dst=1,val=39 \
     -numa dist,src=0,dst=2,val=38 \
     -numa dist,src=0,dst=3,val=37 \
     -numa dist,src=0,dst=4,val=36 \
     -numa dist,src=1,dst=0,val=39 \
     -numa dist,src=1,dst=2,val=38 \
     -numa dist,src=1,dst=3,val=37 \
     -numa dist,src=1,dst=4,val=36 \
     -numa dist,src=2,dst=0,val=38 \
     -numa dist,src=2,dst=1,val=38 \
     -numa dist,src=2,dst=3,val=37 \
     -numa dist,src=2,dst=4,val=36 \
     -numa dist,src=3,dst=0,val=37 \
     -numa dist,src=3,dst=1,val=37 \
     -numa dist,src=3,dst=2,val=37 \
     -numa dist,src=3,dst=4,val=36 \
     -numa dist,src=4,dst=0,val=36 \
     -numa dist,src=4,dst=1,val=36 \
     -numa dist,src=4,dst=2,val=36 \
     -numa dist,src=4,dst=3,val=36 \
     ...

  [ prateek: Moved common functions to include/linux/sched/topology.h,
    reuse the common bits for s390 and ppc, commit message ]

Closes: https://lore.kernel.org/lkml/20250610110701.GA256154@unreal/ [1]
Fixes: ccf74128d6 ("sched/topology: Assert non-NUMA topology masks don't (partially) overlap") # ce29a7da84, f55dac1daf
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reported-by: Leon Romanovsky <leon@kernel.org>
Signed-off-by: K Prateek Nayak <kprateek.nayak@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Reviewed-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Tested-by: Valentin Schneider <vschneid@redhat.com> # x86
Tested-by: Shrikanth Hegde <sshegde@linux.ibm.com> # powerpc
Link: https://lore.kernel.org/lkml/a3de98387abad28592e6ab591f3ff6107fe01dc1.1755893468.git.tim.c.chen@linux.intel.com/ [2]
2025-09-03 10:03:12 +02:00
Harshit Agarwal 8fd5485fb4 sched/deadline: Fix race in push_dl_task()
When a CPU chooses to call push_dl_task and picks a task to push to
another CPU's runqueue then it will call find_lock_later_rq method
which would take a double lock on both CPUs' runqueues. If one of the
locks aren't readily available, it may lead to dropping the current
runqueue lock and reacquiring both the locks at once. During this window
it is possible that the task is already migrated and is running on some
other CPU. These cases are already handled. However, if the task is
migrated and has already been executed and another CPU is now trying to
wake it up (ttwu) such that it is queued again on the runqeue
(on_rq is 1) and also if the task was run by the same CPU, then the
current checks will pass even though the task was migrated out and is no
longer in the pushable tasks list.
Please go through the original rt change for more details on the issue.

To fix this, after the lock is obtained inside the find_lock_later_rq,
it ensures that the task is still at the head of pushable tasks list.
Also removed some checks that are no longer needed with the addition of
this new check.
However, the new check of pushable tasks list only applies when
find_lock_later_rq is called by push_dl_task. For the other caller i.e.
dl_task_offline_migration, existing checks are used.

Signed-off-by: Harshit Agarwal <harshit@nutanix.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Juri Lelli <juri.lelli@redhat.com>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20250408045021.3283624-1-harshit@nutanix.com
2025-09-03 10:03:12 +02:00
Linus Torvalds fe3ad7a58b - Fix a stall on the CPU offline path due to mis-counting a deadline server
task twice as part of the runqueue's running tasks count
 
 - Fix a realtime tasks starvation case where failure to enqueue a timer whose
   expiration time is already in the past would cause repeated attempts to
   re-enqueue a deadline server task which leads to starving the former,
   realtime one
 
 - Prevent a delayed deadline server task stop from breaking the per-runqueue
   bandwidth tracking
 
 - Have a function checking whether the deadline server task has stopped,
   return the correct value
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Merge tag 'sched_urgent_for_v6.17_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler fixes from Borislav Petkov:

 - Fix a stall on the CPU offline path due to mis-counting a deadline
   server task twice as part of the runqueue's running tasks count

 - Fix a realtime tasks starvation case where failure to enqueue a timer
   whose expiration time is already in the past would cause repeated
   attempts to re-enqueue a deadline server task which leads to starving
   the former, realtime one

 - Prevent a delayed deadline server task stop from breaking the
   per-runqueue bandwidth tracking

 - Have a function checking whether the deadline server task has
   stopped, return the correct value

* tag 'sched_urgent_for_v6.17_rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/deadline: Don't count nr_running for dl_server proxy tasks
  sched/deadline: Fix RT task potential starvation when expiry time passed
  sched/deadline: Always stop dl-server before changing parameters
  sched/deadline: Fix dl_server_stopped()
2025-08-31 09:13:00 -07:00
Linus Torvalds 4d28e28098 dma-mapping fixes for Linux 6.17
- another small fix relevant to arm64 systems with memory encryption
 (Shanker Donthineni)
 - fix relevant to arm32 systems with non-standard CMA configuration
 (Oreoluwa Babatunde)
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Merge tag 'dma-mapping-6.17-2025-08-28' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux

Pull dma-mapping fixes from Marek Szyprowski:

 - another small fix for arm64 systems with memory encryption (Shanker
   Donthineni)

 - fix for arm32 systems with non-standard CMA configuration (Oreoluwa
   Babatunde)

* tag 'dma-mapping-6.17-2025-08-28' of git://git.kernel.org/pub/scm/linux/kernel/git/mszyprowski/linux:
  dma/pool: Ensure DMA_DIRECT_REMAP allocations are decrypted
  of: reserved_mem: Restructure call site for dma_contiguous_early_fixup()
2025-08-28 16:04:14 -07:00
Yicong Yang 52d15521eb sched/deadline: Don't count nr_running for dl_server proxy tasks
On CPU offline the kernel stalled with below call trace:

  INFO: task kworker/0:1:11 blocked for more than 120 seconds.

cpuhp hold the cpu hotplug lock endless and stalled vmstat_shepherd.
This is because we count nr_running twice on cpuhp enqueuing and failed
the wait condition of cpuhp:

  enqueue_task_fair() // pick cpuhp from idle, rq->nr_running = 0
    dl_server_start()
      [...]
      add_nr_running() // rq->nr_running = 1
    add_nr_running() // rq->nr_running = 2
  [switch to cpuhp, waiting on balance_hotplug_wait()]
  rcuwait_wait_event(rq->nr_running == 1 && ...) // failed, rq->nr_running=2
    schedule() // wait again

It doesn't make sense to count the dl_server towards runnable tasks,
since it runs other tasks.

Fixes: 63ba8422f8 ("sched/deadline: Introduce deadline servers")
Signed-off-by: Yicong Yang <yangyicong@hisilicon.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/20250627035420.37712-1-yangyicong@huawei.com
2025-08-26 10:46:01 +02:00
kuyo chang 421fc59cf5 sched/deadline: Fix RT task potential starvation when expiry time passed
[Symptom]
The fair server mechanism, which is intended to prevent fair starvation
when higher-priority tasks monopolize the CPU.
Specifically, RT tasks on the runqueue may not be scheduled as expected.

[Analysis]
The log "sched: DL replenish lagged too much" triggered.

By memory dump of dl_server:
    curr = 0xFFFFFF80D6A0AC00 (
      dl_server = 0xFFFFFF83CD5B1470(
        dl_runtime = 0x02FAF080,
        dl_deadline = 0x3B9ACA00,
        dl_period = 0x3B9ACA00,
        dl_bw = 0xCCCC,
        dl_density = 0xCCCC,
        runtime = 0x02FAF080,
        deadline = 0x0000082031EB0E80,
        flags = 0x0,
        dl_throttled = 0x0,
        dl_yielded = 0x0,
        dl_non_contending = 0x0,
        dl_overrun = 0x0,
        dl_server = 0x1,
        dl_server_active = 0x1,
        dl_defer = 0x1,
        dl_defer_armed = 0x0,
        dl_defer_running = 0x1,
        dl_timer = (
          node = (
            expires = 0x000008199756E700),
          _softexpires = 0x000008199756E700,
          function = 0xFFFFFFDB9AF44D30 = dl_task_timer,
          base = 0xFFFFFF83CD5A12C0,
          state = 0x0,
          is_rel = 0x0,
          is_soft = 0x0,
    clock_update_flags = 0x4,
    clock = 0x000008204A496900,

 - The timer expiration time (rq->curr->dl_server->dl_timer->expires)
   is already in the past, indicating the timer has expired.
 - The timer state (rq->curr->dl_server->dl_timer->state) is 0.

[Suspected Root Cause]
The relevant code flow in the throttle path of
update_curr_dl_se() as follows:

  dequeue_dl_entity(dl_se, 0);                // the DL entity is dequeued

  if (unlikely(is_dl_boosted(dl_se) || !start_dl_timer(dl_se))) {
      if (dl_server(dl_se))                   // timer registration fails
          enqueue_dl_entity(dl_se, ENQUEUE_REPLENISH);//enqueue immediately
      ...
  }

The failure of `start_dl_timer` is caused by attempting to register a
timer with an expiration time that is already in the past. When this
situation persists, the code repeatedly re-enqueues the DL entity
without properly replenishing or restarting the timer, resulting in RT
task may not be scheduled as expected.

[Proposed Solution]:
Instead of immediately re-enqueuing the DL entity on timer registration
failure, this change ensures the DL entity is properly replenished and
the timer is restarted, preventing RT potential starvation.

Fixes: 63ba8422f8 ("sched/deadline: Introduce deadline servers")
Signed-off-by: kuyo chang <kuyo.chang@mediatek.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Closes: https://lore.kernel.org/CAMuHMdXn4z1pioTtBGMfQM0jsLviqS2jwysaWXpoLxWYoGa82w@mail.gmail.com
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Tested-by: Jiri Slaby <jirislaby@kernel.org>
Tested-by: Diederik de Haas <didi.debian@cknow.org>
Link: https://lkml.kernel.org/r/20250615131129.954975-1-kuyo.chang@mediatek.com
2025-08-26 10:46:01 +02:00
Juri Lelli bb4700adc3 sched/deadline: Always stop dl-server before changing parameters
Commit cccb45d7c4 ("sched/deadline: Less agressive dl_server
handling") reduced dl-server overhead by delaying disabling servers only
after there are no fair task around for a whole period, which means that
deadline entities are not dequeued right away on a server stop event.
However, the delay opens up a window in which a request for changing
server parameters can break per-runqueue running_bw tracking, as
reported by Yuri.

Close the problematic window by unconditionally calling dl_server_stop()
before applying the new parameters (ensuring deadline entities go
through an actual dequeue).

Fixes: cccb45d7c4 ("sched/deadline: Less agressive dl_server handling")
Reported-by: Yuri Andriaccio <yurand2000@gmail.com>
Signed-off-by: Juri Lelli <juri.lelli@redhat.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Valentin Schneider <vschneid@redhat.com>
Link: https://lore.kernel.org/r/20250721-upstream-fix-dlserver-lessaggressive-b4-v1-1-4ebc10c87e40@redhat.com
2025-08-26 10:46:00 +02:00
Huacai Chen 4717432dfd sched/deadline: Fix dl_server_stopped()
Commit cccb45d7c4 ("sched/deadline: Less agressive dl_server handling")
introduces dl_server_stopped(). But it is obvious that dl_server_stopped()
should return true if dl_se->dl_server_active is 0.

Fixes: cccb45d7c4 ("sched/deadline: Less agressive dl_server handling")
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250809130419.1980742-1-chenhuacai@loongson.cn
2025-08-26 10:46:00 +02:00
Linus Torvalds 69fd6b99b8 - Fix a case where the events throttling logic operates on inactive events
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Merge tag 'perf_urgent_for_v6.17_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull perf fix from Borislav Petkov:

 - Fix a case where the events throttling logic operates on inactive
   events

* tag 'perf_urgent_for_v6.17_rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf: Avoid undefined behavior from stopping/starting inactive events
2025-08-24 10:13:05 -04:00
Linus Torvalds 14f84cd318 Modules fixes for 6.17-rc3
This includes a fix part of the KSPP (Kernel Self Protection Project) to replace
 the deprecated and unsafe strcpy() calls in the kernel parameter string handler
 and sysfs parameters for built-in modules. Single commit, no functional changes.
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Merge tag 'modules-6.17-rc3.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/modules/linux

Pull modules fix from Daniel Gomez:
 "This includes a fix part of the KSPP (Kernel Self Protection Project)
  to replace the deprecated and unsafe strcpy() calls in the kernel
  parameter string handler and sysfs parameters for built-in modules.
  Single commit, no functional changes"

* tag 'modules-6.17-rc3.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/modules/linux:
  params: Replace deprecated strcpy() with strscpy() and memcpy()
2025-08-24 09:43:50 -04:00
Linus Torvalds e1d8f9ccb2 tracing fixes for v6.17-rc2:
- Fix rtla and latency tooling pkg-config errors
 
   If libtraceevent and libtracefs is installed, but their corresponding '.pc'
   files are not installed, it reports that the libraries are missing and
   confuses the developer. Instead, report that the pkg-config files are
   missing and should be installed.
 
 - Fix overflow bug of the parser in trace_get_user()
 
   trace_get_user() uses the parsing functions to parse the user space strings.
   If the parser fails due to incorrect processing, it doesn't terminate the
   buffer with a nul byte. Add a "failed" flag to the parser that gets set when
   parsing fails and is used to know if the buffer is fine to use or not.
 
 - Remove a semicolon that was at an end of a comment line
 
 - Fix register_ftrace_graph() to unregister the pm notifier on error
 
   The register_ftrace_graph() registers a pm notifier but there's an error
   path that can exit the function without unregistering it. Since the function
   returns an error, it will never be unregistered.
 
 - Allocate and copy ftrace hash for reader of ftrace filter files
 
   When the set_ftrace_filter or set_ftrace_notrace files are open for read,
   an iterator is created and sets its hash pointer to the associated hash that
   represents filtering or notrace filtering to it. The issue is that the hash
   it points to can change while the iteration is happening. All the locking
   used to access the tracer's hashes are released which means those hashes can
   change or even be freed. Using the hash pointed to by the iterator can cause
   UAF bugs or similar.
 
   Have the read of these files allocate and copy the corresponding hashes and
   use that as that will keep them the same while the iterator is open. This
   also simplifies the code as opening it for write already does an allocate
   and copy, and now that the read is doing the same, there's no need to check
   which way it was opened on the release of the file, and the iterator hash
   can always be freed.
 
 - Fix function graph to copy args into temp storage
 
   The output of the function graph tracer shows both the entry and the exit of
   a function. When the exit is right after the entry, it combines the two
   events into one with the output of "function();", instead of showing:
 
   function() {
   }
 
   In order to do this, the iterator descriptor that reads the events includes
   storage that saves the entry event while it peaks at the next event in
   the ring buffer. The peek can free the entry event so the iterator must
   store the information to use it after the peek.
 
   With the addition of function graph tracer recording the args, where the
   args are a dynamic array in the entry event, the temp storage does not save
   them. This causes the args to be corrupted or even cause a read of unsafe
   memory.
 
   Add space to save the args in the temp storage of the iterator.
 
 - Fix race between ftrace_dump and reading trace_pipe
 
   ftrace_dump() is used when a crash occurs where the ftrace buffer will be
   printed to the console. But it can also be triggered by sysrq-z. If a
   sysrq-z is triggered while a task is reading trace_pipe it can cause a race
   in the ftrace_dump() where it checks if the buffer has content, then it
   checks if the next event is available, and then prints the output
   (regardless if the next event was available or not). Reading trace_pipe
   at the same time can cause it to not be available, and this triggers a
   WARN_ON in the print. Move the printing into the check if the next event
   exists or not.
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Merge tag 'trace-v6.17-rc2-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull tracing fixes from Steven Rostedt:

 - Fix rtla and latency tooling pkg-config errors

   If libtraceevent and libtracefs is installed, but their corresponding
   '.pc' files are not installed, it reports that the libraries are
   missing and confuses the developer. Instead, report that the
   pkg-config files are missing and should be installed.

 - Fix overflow bug of the parser in trace_get_user()

   trace_get_user() uses the parsing functions to parse the user space
   strings. If the parser fails due to incorrect processing, it doesn't
   terminate the buffer with a nul byte. Add a "failed" flag to the
   parser that gets set when parsing fails and is used to know if the
   buffer is fine to use or not.

 - Remove a semicolon that was at an end of a comment line

 - Fix register_ftrace_graph() to unregister the pm notifier on error

   The register_ftrace_graph() registers a pm notifier but there's an
   error path that can exit the function without unregistering it. Since
   the function returns an error, it will never be unregistered.

 - Allocate and copy ftrace hash for reader of ftrace filter files

   When the set_ftrace_filter or set_ftrace_notrace files are open for
   read, an iterator is created and sets its hash pointer to the
   associated hash that represents filtering or notrace filtering to it.
   The issue is that the hash it points to can change while the
   iteration is happening. All the locking used to access the tracer's
   hashes are released which means those hashes can change or even be
   freed. Using the hash pointed to by the iterator can cause UAF bugs
   or similar.

   Have the read of these files allocate and copy the corresponding
   hashes and use that as that will keep them the same while the
   iterator is open. This also simplifies the code as opening it for
   write already does an allocate and copy, and now that the read is
   doing the same, there's no need to check which way it was opened on
   the release of the file, and the iterator hash can always be freed.

 - Fix function graph to copy args into temp storage

   The output of the function graph tracer shows both the entry and the
   exit of a function. When the exit is right after the entry, it
   combines the two events into one with the output of "function();",
   instead of showing:

     function() {
     }

   In order to do this, the iterator descriptor that reads the events
   includes storage that saves the entry event while it peaks at the
   next event in the ring buffer. The peek can free the entry event so
   the iterator must store the information to use it after the peek.

   With the addition of function graph tracer recording the args, where
   the args are a dynamic array in the entry event, the temp storage
   does not save them. This causes the args to be corrupted or even
   cause a read of unsafe memory.

   Add space to save the args in the temp storage of the iterator.

 - Fix race between ftrace_dump and reading trace_pipe

   ftrace_dump() is used when a crash occurs where the ftrace buffer
   will be printed to the console. But it can also be triggered by
   sysrq-z. If a sysrq-z is triggered while a task is reading trace_pipe
   it can cause a race in the ftrace_dump() where it checks if the
   buffer has content, then it checks if the next event is available,
   and then prints the output (regardless if the next event was
   available or not). Reading trace_pipe at the same time can cause it
   to not be available, and this triggers a WARN_ON in the print. Move
   the printing into the check if the next event exists or not

* tag 'trace-v6.17-rc2-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ftrace: Also allocate and copy hash for reading of filter files
  ftrace: Fix potential warning in trace_printk_seq during ftrace_dump
  fgraph: Copy args in intermediate storage with entry
  trace/fgraph: Fix the warning caused by missing unregister notifier
  ring-buffer: Remove redundant semicolons
  tracing: Limit access to parser->buffer when trace_get_user failed
  rtla: Check pkg-config install
  tools/latency-collector: Check pkg-config install
2025-08-23 10:11:34 -04:00
Steven Rostedt bfb336cf97 ftrace: Also allocate and copy hash for reading of filter files
Currently the reader of set_ftrace_filter and set_ftrace_notrace just adds
the pointer to the global tracer hash to its iterator. Unlike the writer
that allocates a copy of the hash, the reader keeps the pointer to the
filter hashes. This is problematic because this pointer is static across
function calls that release the locks that can update the global tracer
hashes. This can cause UAF and similar bugs.

Allocate and copy the hash for reading the filter files like it is done
for the writers. This not only fixes UAF bugs, but also makes the code a
bit simpler as it doesn't have to differentiate when to free the
iterator's hash between writers and readers.

Cc: stable@vger.kernel.org
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/20250822183606.12962cc3@batman.local.home
Fixes: c20489dad1 ("ftrace: Assign iter->hash to filter or notrace hashes on seq read")
Closes: https://lore.kernel.org/all/20250813023044.2121943-1-wutengda@huaweicloud.com/
Closes: https://lore.kernel.org/all/20250822192437.GA458494@ax162/
Reported-by: Tengda Wu <wutengda@huaweicloud.com>
Tested-by: Tengda Wu <wutengda@huaweicloud.com>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-08-22 19:58:35 -04:00
Tengda Wu 4013aef2ce ftrace: Fix potential warning in trace_printk_seq during ftrace_dump
When calling ftrace_dump_one() concurrently with reading trace_pipe,
a WARN_ON_ONCE() in trace_printk_seq() can be triggered due to a race
condition.

The issue occurs because:

CPU0 (ftrace_dump)                              CPU1 (reader)
echo z > /proc/sysrq-trigger

!trace_empty(&iter)
trace_iterator_reset(&iter) <- len = size = 0
                                                cat /sys/kernel/tracing/trace_pipe
trace_find_next_entry_inc(&iter)
  __find_next_entry
    ring_buffer_empty_cpu <- all empty
  return NULL

trace_printk_seq(&iter.seq)
  WARN_ON_ONCE(s->seq.len >= s->seq.size)

In the context between trace_empty() and trace_find_next_entry_inc()
during ftrace_dump, the ring buffer data was consumed by other readers.
This caused trace_find_next_entry_inc to return NULL, failing to populate
`iter.seq`. At this point, due to the prior trace_iterator_reset, both
`iter.seq.len` and `iter.seq.size` were set to 0. Since they are equal,
the WARN_ON_ONCE condition is triggered.

Move the trace_printk_seq() into the if block that checks to make sure the
return value of trace_find_next_entry_inc() is non-NULL in
ftrace_dump_one(), ensuring the 'iter.seq' is properly populated before
subsequent operations.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Ingo Molnar <mingo@elte.hu>
Link: https://lore.kernel.org/20250822033343.3000289-1-wutengda@huaweicloud.com
Fixes: d769041f86 ("ring_buffer: implement new locking")
Signed-off-by: Tengda Wu <wutengda@huaweicloud.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-08-22 17:32:36 -04:00
Steven Rostedt e3d01979e4 fgraph: Copy args in intermediate storage with entry
The output of the function graph tracer has two ways to display its
entries. One way for leaf functions with no events recorded within them,
and the other is for functions with events recorded inside it. As function
graph has an entry and exit event, to simplify the output of leaf
functions it combines the two, where as non leaf functions are separate:

 2)               |              invoke_rcu_core() {
 2)               |                raise_softirq() {
 2)   0.391 us    |                  __raise_softirq_irqoff();
 2)   1.191 us    |                }
 2)   2.086 us    |              }

The __raise_softirq_irqoff() function above is really two events that were
merged into one. Otherwise it would have looked like:

 2)               |              invoke_rcu_core() {
 2)               |                raise_softirq() {
 2)               |                  __raise_softirq_irqoff() {
 2)   0.391 us    |                  }
 2)   1.191 us    |                }
 2)   2.086 us    |              }

In order to do this merge, the reading of the trace output file needs to
look at the next event before printing. But since the pointer to the event
is on the ring buffer, it needs to save the entry event before it looks at
the next event as the next event goes out of focus as soon as a new event
is read from the ring buffer. After it reads the next event, it will print
the entry event with either the '{' (non leaf) or ';' and timestamps (leaf).

The iterator used to read the trace file has storage for this event. The
problem happens when the function graph tracer has arguments attached to
the entry event as the entry now has a variable length "args" field. This
field only gets set when funcargs option is used. But the args are not
recorded in this temp data and garbage could be printed. The entry field
is copied via:

  data->ent = *curr;

Where "curr" is the entry field. But this method only saves the non
variable length fields from the structure.

Add a helper structure to the iterator data that adds the max args size to
the data storage in the iterator. Then simply copy the entire entry into
this storage (with size protection).

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/20250820195522.51d4a268@gandalf.local.home
Reported-by: Sasha Levin <sashal@kernel.org>
Tested-by: Sasha Levin <sashal@kernel.org>
Closes: https://lore.kernel.org/all/aJaxRVKverIjF4a6@lappy/
Fixes: ff5c9c576e ("ftrace: Add support for function argument to graph tracer")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-08-22 17:32:35 -04:00
Linus Torvalds 6eba757ce9 20 hotfixes. 10 are cc:stable and the remainder address post-6.16 issues
or aren't considered necessary for -stable kernels.  17 of these fixes are
 for MM.
 
 As usual, singletons all over the place, apart from a three-patch series
 of KHO followup work from Pasha which is actually also a bunch of
 singletons.
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Merge tag 'mm-hotfixes-stable-2025-08-21-18-17' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull misc fixes from Andrew Morton:
 "20 hotfixes. 10 are cc:stable and the remainder address post-6.16
  issues or aren't considered necessary for -stable kernels. 17 of these
  fixes are for MM.

  As usual, singletons all over the place, apart from a three-patch
  series of KHO followup work from Pasha which is actually also a bunch
  of singletons"

* tag 'mm-hotfixes-stable-2025-08-21-18-17' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  mm/mremap: fix WARN with uffd that has remap events disabled
  mm/damon/sysfs-schemes: put damos dests dir after removing its files
  mm/migrate: fix NULL movable_ops if CONFIG_ZSMALLOC=m
  mm/damon/core: fix damos_commit_filter not changing allow
  mm/memory-failure: fix infinite UCE for VM_PFNMAP pfn
  MAINTAINERS: mark MGLRU as maintained
  mm: rust: add page.rs to MEMORY MANAGEMENT - RUST
  iov_iter: iterate_folioq: fix handling of offset >= folio size
  selftests/damon: fix selftests by installing drgn related script
  .mailmap: add entry for Easwar Hariharan
  selftests/mm: add test for invalid multi VMA operations
  mm/mremap: catch invalid multi VMA moves earlier
  mm/mremap: allow multi-VMA move when filesystem uses thp_get_unmapped_area
  mm/damon/core: fix commit_ops_filters by using correct nth function
  tools/testing: add linux/args.h header and fix radix, VMA tests
  mm/debug_vm_pgtable: clear page table entries at destroy_args()
  squashfs: fix memory leak in squashfs_fill_super
  kho: warn if KHO is disabled due to an error
  kho: mm: don't allow deferred struct page with KHO
  kho: init new_physxa->phys_bits to fix lockdep
2025-08-22 08:54:34 -04:00
Linus Torvalds 3957a57201 cgroup: Fixes for v6.17-rc2
- Fix NULL de-ref in css_rstat_exit() which could happen after allocation
   failure.
 
 - Fix a cpuset partition handling bug and a couple other misc issues.
 
 - Doc spelling fix.
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Merge tag 'cgroup-for-6.17-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup fixes from Tejun Heo:

 - Fix NULL de-ref in css_rstat_exit() which could happen after
   allocation failure

 - Fix a cpuset partition handling bug and a couple other misc issues

 - Doc spelling fix

* tag 'cgroup-for-6.17-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  docs: cgroup: fixed spelling mistakes in documentation
  cgroup: avoid null de-ref in css_rstat_exit()
  cgroup/cpuset: Remove the unnecessary css_get/put() in cpuset_partition_write()
  cgroup/cpuset: Fix a partition error with CPU hotplug
  cgroup/cpuset: Use static_branch_enable_cpuslocked() on cpusets_insane_config_key
2025-08-21 16:31:27 -04:00
Linus Torvalds d72052ac09 sched_ext: Fixes for v6.17-rc2
- Fix a subtle bug during SCX enabling where a dead task skips init but
   doesn't skip sched class switch leading to invalid task state transition
   warning.
 
 - Cosmetic fix in selftests.
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Merge tag 'sched_ext-for-6.17-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext

Pull sched_ext fixes from Tejun Heo:

 - Fix a subtle bug during SCX enabling where a dead task skips init
   but doesn't skip sched class switch leading to invalid task state
   transition warning

 - Cosmetic fix in selftests

* tag 'sched_ext-for-6.17-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/sched_ext:
  selftests/sched_ext: Remove duplicate sched.h header
  sched/ext: Fix invalid task state transitions on class switch
2025-08-21 16:02:35 -04:00
Linus Torvalds 068a56e56f Probes fixes for v6.17-rc2:
- tracing: fprobe-event: Sanitize wildcard for fprobe event name
   Fprobe event accepts wildcards for the target functions, but
   unless the user specifies its event name, it makes an event with
   the wildcards. Replace the wildcard '*' with the underscore '_'.
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Merge tag 'probes-fixes-v6.17-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

Pull probes fix from Masami Hiramatsu:
 "Sanitize wildcard for fprobe event name

  Fprobe event accepts wildcards for the target functions, but unless
  the user specifies its event name, it makes an event with the
  wildcards. Replace the wildcard '*' with the underscore '_'"

* tag 'probes-fixes-v6.17-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  tracing: fprobe-event: Sanitize wildcard for fprobe event name
2025-08-20 16:29:30 -07:00
Masami Hiramatsu (Google) ec879e1a0b tracing: fprobe-event: Sanitize wildcard for fprobe event name
Fprobe event accepts wildcards for the target functions, but unless user
specifies its event name, it makes an event with the wildcards.

  /sys/kernel/tracing # echo 'f mutex*' >> dynamic_events
  /sys/kernel/tracing # cat dynamic_events
  f:fprobes/mutex*__entry mutex*
  /sys/kernel/tracing # ls events/fprobes/
  enable         filter         mutex*__entry

To fix this, replace the wildcard ('*') with an underscore.

Link: https://lore.kernel.org/all/175535345114.282990.12294108192847938710.stgit@devnote2/

Fixes: 334e5519c3 ("tracing/probes: Add fprobe events for tracing function entry and exit.")
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Cc: stable@vger.kernel.org
2025-08-20 23:41:58 +09:00
Ye Weihua edede7a6dc trace/fgraph: Fix the warning caused by missing unregister notifier
This warning was triggered during testing on v6.16:

notifier callback ftrace_suspend_notifier_call already registered
WARNING: CPU: 2 PID: 86 at kernel/notifier.c:23 notifier_chain_register+0x44/0xb0
...
Call Trace:
 <TASK>
 blocking_notifier_chain_register+0x34/0x60
 register_ftrace_graph+0x330/0x410
 ftrace_profile_write+0x1e9/0x340
 vfs_write+0xf8/0x420
 ? filp_flush+0x8a/0xa0
 ? filp_close+0x1f/0x30
 ? do_dup2+0xaf/0x160
 ksys_write+0x65/0xe0
 do_syscall_64+0xa4/0x260
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

When writing to the function_profile_enabled interface, the notifier was
not unregistered after start_graph_tracing failed, causing a warning the
next time function_profile_enabled was written.

Fixed by adding unregister_pm_notifier in the exception path.

Link: https://lore.kernel.org/20250818073332.3890629-1-yeweihua4@huawei.com
Fixes: 4a2b8dda3f ("tracing/function-graph-tracer: fix a regression while suspend to disk")
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Ye Weihua <yeweihua4@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-08-20 09:21:03 -04:00
Liao Yuanhong cd6e4faba9 ring-buffer: Remove redundant semicolons
Remove unnecessary semicolons.

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250813095114.559530-1-liaoyuanhong@vivo.com
Signed-off-by: Liao Yuanhong <liaoyuanhong@vivo.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-08-20 09:20:30 -04:00
Pu Lehui 6a909ea83f tracing: Limit access to parser->buffer when trace_get_user failed
When the length of the string written to set_ftrace_filter exceeds
FTRACE_BUFF_MAX, the following KASAN alarm will be triggered:

BUG: KASAN: slab-out-of-bounds in strsep+0x18c/0x1b0
Read of size 1 at addr ffff0000d00bd5ba by task ash/165

CPU: 1 UID: 0 PID: 165 Comm: ash Not tainted 6.16.0-g6bcdbd62bd56-dirty
Hardware name: linux,dummy-virt (DT)
Call trace:
 show_stack+0x34/0x50 (C)
 dump_stack_lvl+0xa0/0x158
 print_address_description.constprop.0+0x88/0x398
 print_report+0xb0/0x280
 kasan_report+0xa4/0xf0
 __asan_report_load1_noabort+0x20/0x30
 strsep+0x18c/0x1b0
 ftrace_process_regex.isra.0+0x100/0x2d8
 ftrace_regex_release+0x484/0x618
 __fput+0x364/0xa58
 ____fput+0x28/0x40
 task_work_run+0x154/0x278
 do_notify_resume+0x1f0/0x220
 el0_svc+0xec/0xf0
 el0t_64_sync_handler+0xa0/0xe8
 el0t_64_sync+0x1ac/0x1b0

The reason is that trace_get_user will fail when processing a string
longer than FTRACE_BUFF_MAX, but not set the end of parser->buffer to 0.
Then an OOB access will be triggered in ftrace_regex_release->
ftrace_process_regex->strsep->strpbrk. We can solve this problem by
limiting access to parser->buffer when trace_get_user failed.

Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/20250813040232.1344527-1-pulehui@huaweicloud.com
Fixes: 8c9af478c0 ("ftrace: Handle commands when closing set_ftrace_filter file")
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
2025-08-20 09:20:30 -04:00
Pasha Tatashin 44958f2025 kho: warn if KHO is disabled due to an error
During boot scratch area is allocated based on command line parameters or
auto calculated.  However, scratch area may fail to allocate, and in that
case KHO is disabled.  Currently, no warning is printed that KHO is
disabled, which makes it confusing for the end user to figure out why KHO
is not available.  Add the missing warning message.

Link: https://lkml.kernel.org/r/20250808201804.772010-4-pasha.tatashin@soleen.com
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Changyuan Lyu <changyuanl@google.com>
Cc: Coiby Xu <coxu@redhat.com>
Cc: Dave Vasilevsky <dave@vasilevsky.ca>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Kees Cook <kees@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-08-19 16:35:53 -07:00
Pasha Tatashin 8b66ed2c3f kho: mm: don't allow deferred struct page with KHO
KHO uses struct pages for the preserved memory early in boot, however,
with deferred struct page initialization, only a small portion of memory
has properly initialized struct pages.

This problem was detected where vmemmap is poisoned, and illegal flag
combinations are detected.

Don't allow them to be enabled together, and later we will have to teach
KHO to work properly with deferred struct page init kernel feature.

Link: https://lkml.kernel.org/r/20250808201804.772010-3-pasha.tatashin@soleen.com
Fixes: 4e1d010e3b ("kexec: add config option for KHO")
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Changyuan Lyu <changyuanl@google.com>
Cc: Coiby Xu <coxu@redhat.com>
Cc: Dave Vasilevsky <dave@vasilevsky.ca>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Kees Cook <kees@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-08-19 16:35:53 -07:00
Pasha Tatashin 63b17b653d kho: init new_physxa->phys_bits to fix lockdep
Patch series "Several KHO Hotfixes".

Three unrelated fixes for Kexec Handover.


This patch (of 3):

Lockdep shows the following warning:

INFO: trying to register non-static key.  The code is fine but needs
lockdep annotation, or maybe you didn't initialize this object before use?
turning off the locking correctness validator.

[<ffffffff810133a6>] dump_stack_lvl+0x66/0xa0
[<ffffffff8136012c>] assign_lock_key+0x10c/0x120
[<ffffffff81358bb4>] register_lock_class+0xf4/0x2f0
[<ffffffff813597ff>] __lock_acquire+0x7f/0x2c40
[<ffffffff81360cb0>] ? __pfx_hlock_conflict+0x10/0x10
[<ffffffff811707be>] ? native_flush_tlb_global+0x8e/0xa0
[<ffffffff8117096e>] ? __flush_tlb_all+0x4e/0xa0
[<ffffffff81172fc2>] ? __kernel_map_pages+0x112/0x140
[<ffffffff813ec327>] ? xa_load_or_alloc+0x67/0xe0
[<ffffffff81359556>] lock_acquire+0xe6/0x280
[<ffffffff813ec327>] ? xa_load_or_alloc+0x67/0xe0
[<ffffffff8100b9e0>] _raw_spin_lock+0x30/0x40
[<ffffffff813ec327>] ? xa_load_or_alloc+0x67/0xe0
[<ffffffff813ec327>] xa_load_or_alloc+0x67/0xe0
[<ffffffff813eb4c0>] kho_preserve_folio+0x90/0x100
[<ffffffff813ebb7f>] __kho_finalize+0xcf/0x400
[<ffffffff813ebef4>] kho_finalize+0x34/0x70

This is becase xa has its own lock, that is not initialized in
xa_load_or_alloc.

Modifiy __kho_preserve_order(), to properly call
xa_init(&new_physxa->phys_bits);

Link: https://lkml.kernel.org/r/20250808201804.772010-2-pasha.tatashin@soleen.com
Fixes: fc33e4b44b ("kexec: enable KHO support for memory preservation")
Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Alexander Graf <graf@amazon.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baoquan He <bhe@redhat.com>
Cc: Changyuan Lyu <changyuanl@google.com>
Cc: Coiby Xu <coxu@redhat.com>
Cc: Dave Vasilevsky <dave@vasilevsky.ca>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Pratyush Yadav <pratyush@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-08-19 16:35:53 -07:00
Linus Torvalds 055f213075 vfs-6.17-rc3.fixes
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Merge tag 'vfs-6.17-rc3.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs fixes from Christian Brauner:

 - Fix two memory leaks in pidfs

 - Prevent changing the idmapping of an already idmapped mount without
   OPEN_TREE_CLONE through open_tree_attr()

 - Don't fail listing extended attributes in kernfs when no extended
   attributes are set

 - Fix the return value in coredump_parse()

 - Fix the error handling for unbuffered writes in netfs

 - Fix broken data integrity guarantees for O_SYNC writes via iomap

 - Fix UAF in __mark_inode_dirty()

 - Keep inode->i_blkbits constant in fuse

 - Fix coredump selftests

 - Fix get_unused_fd_flags() usage in do_handle_open()

 - Rename EXPORT_SYMBOL_GPL_FOR_MODULES to EXPORT_SYMBOL_FOR_MODULES

 - Fix use-after-free in bh_read()

 - Fix incorrect lflags value in the move_mount() syscall

* tag 'vfs-6.17-rc3.fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  signal: Fix memory leak for PIDFD_SELF* sentinels
  kernfs: don't fail listing extended attributes
  coredump: Fix return value in coredump_parse()
  fs/buffer: fix use-after-free when call bh_read() helper
  pidfs: Fix memory leak in pidfd_info()
  netfs: Fix unbuffered write error handling
  fhandle: do_handle_open() should get FD with user flags
  module: Rename EXPORT_SYMBOL_GPL_FOR_MODULES to EXPORT_SYMBOL_FOR_MODULES
  fs: fix incorrect lflags value in the move_mount syscall
  selftests/coredump: Remove the read() that fails the test
  fuse: keep inode->i_blkbits constant
  iomap: Fix broken data integrity guarantees for O_SYNC writes
  selftests/mount_setattr: add smoke tests for open_tree_attr(2) bug
  open_tree_attr: do not allow id-mapping changes without OPEN_TREE_CLONE
  fs: writeback: fix use-after-free in __mark_inode_dirty()
2025-08-19 09:54:47 -07:00
Adrian Huang (Lenovo) a2c1f82618
signal: Fix memory leak for PIDFD_SELF* sentinels
Commit f08d0c3a71 ("pidfd: add PIDFD_SELF* sentinels to refer to own
thread/process") introduced a leak by acquiring a pid reference through
get_task_pid(), which increments pid->count but never drops it with
put_pid().

As a result, kmemleak reports unreferenced pid objects after running
tools/testing/selftests/pidfd/pidfd_test, for example:

  unreferenced object 0xff1100206757a940 (size 160):
    comm "pidfd_test", pid 16965, jiffies 4294853028
    hex dump (first 32 bytes):
      01 00 00 00 00 00 00 00 00 00 00 00 fd 57 50 04  .............WP.
      5e 44 00 00 00 00 00 00 18 de 34 17 01 00 11 ff  ^D........4.....
    backtrace (crc cd8844d4):
      kmem_cache_alloc_noprof+0x2f4/0x3f0
      alloc_pid+0x54/0x3d0
      copy_process+0xd58/0x1740
      kernel_clone+0x99/0x3b0
      __do_sys_clone3+0xbe/0x100
      do_syscall_64+0x7b/0x2c0
      entry_SYSCALL_64_after_hwframe+0x76/0x7e

Fix this by calling put_pid() after do_pidfd_send_signal() returns.

Fixes: f08d0c3a71 ("pidfd: add PIDFD_SELF* sentinels to refer to own thread/process")
Signed-off-by: Adrian Huang (Lenovo) <adrianhuang0701@gmail.com>
Link: https://lore.kernel.org/20250818134310.12273-1-adrianhuang0701@gmail.com
Tested-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2025-08-19 13:51:28 +02:00
Linus Torvalds 0a9ee9ce49 - Make sure sanity checks down in the mutex lock path happen on the correct
type of task so that they don't trigger falsely
 
 - Use the write unsafe user access pairs when writing a futex value to prevent
   an error on PowerPC which does user read and write accesses differently
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Merge tag 'locking_urgent_for_v6.17_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking fixes from Borislav Petkov:

 - Make sure sanity checks down in the mutex lock path happen on the
   correct type of task so that they don't trigger falsely

 - Use the write unsafe user access pairs when writing a futex value to
   prevent an error on PowerPC which does user read and write accesses
   differently

* tag 'locking_urgent_for_v6.17_rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking: Fix __clear_task_blocked_on() warning from __ww_mutex_wound() path
  futex: Use user_write_access_begin/_end() in futex_put_value()
2025-08-17 05:57:47 -07:00
Thorsten Blum 5eb4b9a4cd
params: Replace deprecated strcpy() with strscpy() and memcpy()
strcpy() is deprecated; use strscpy() and memcpy() instead.

In param_set_copystring(), we can safely use memcpy() because we already
know the length of the source string 'val' and that it is guaranteed to
be NUL-terminated within the first 'kps->maxlen' bytes.

Link: https://github.com/KSPP/linux/issues/88
Signed-off-by: Thorsten Blum <thorsten.blum@linux.dev>
Reviewed-by: Daniel Gomez <da.gomez@samsung.com>
Reviewed-by: Petr Pavlu <petr.pavlu@suse.com>
Link: https://lore.kernel.org/r/20250813132200.184064-2-thorsten.blum@linux.dev
Signed-off-by: Daniel Gomez <da.gomez@samsung.com>
2025-08-16 21:47:25 +02:00
Yunseong Kim b64fdd422a perf: Avoid undefined behavior from stopping/starting inactive events
Calling pmu->start()/stop() on perf events in PERF_EVENT_STATE_OFF can
leave event->hw.idx at -1. When PMU drivers later attempt to use this
negative index as a shift exponent in bitwise operations, it leads to UBSAN
shift-out-of-bounds reports.

The issue is a logical flaw in how event groups handle throttling when some
members are intentionally disabled. Based on the analysis and the
reproducer provided by Mark Rutland (this issue on both arm64 and x86-64).

The scenario unfolds as follows:

 1. A group leader event is configured with a very aggressive sampling
    period (e.g., sample_period = 1). This causes frequent interrupts and
    triggers the throttling mechanism.
 2. A child event in the same group is created in a disabled state
    (.disabled = 1). This event remains in PERF_EVENT_STATE_OFF.
    Since it hasn't been scheduled onto the PMU, its event->hw.idx remains
    initialized at -1.
 3. When throttling occurs, perf_event_throttle_group() and later
    perf_event_unthrottle_group() iterate through all siblings, including
    the disabled child event.
 4. perf_event_throttle()/unthrottle() are called on this inactive child
    event, which then call event->pmu->start()/stop().
 5. The PMU driver receives the event with hw.idx == -1 and attempts to
    use it as a shift exponent. e.g., in macros like PMCNTENSET(idx),
    leading to the UBSAN report.

The throttling mechanism attempts to start/stop events that are not
actively scheduled on the hardware.

Move the state check into perf_event_throttle()/perf_event_unthrottle() so
that inactive events are skipped entirely. This ensures only active events
with a valid hw.idx are processed, preventing undefined behavior and
silencing UBSAN warnings. The corrected check ensures true before
proceeding with PMU operations.

The problem can be reproduced with the syzkaller reproducer:

Fixes: 9734e25fbf ("perf: Fix the throttle logic for a group")
Signed-off-by: Yunseong Kim <ysk@kzalloc.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Kan Liang <kan.liang@linux.intel.com>
Link: https://lore.kernel.org/r/20250812181046.292382-2-ysk@kzalloc.com
2025-08-15 13:12:56 +02:00
Linus Torvalds 63467137ec Including fixes from Netfilter and IPsec.
Current release - regressions:
 
   - netfilter: nft_set_pipapo:
     - don't return bogus extension pointer
     - fix null deref for empty set
 
 Current release - new code bugs:
 
   - core: prevent deadlocks when enabling NAPIs with mixed kthread config
 
   - eth: netdevsim: Fix wild pointer access in nsim_queue_free().
 
 Previous releases - regressions:
 
   - page_pool: allow enabling recycling late, fix false positive warning
 
   - sched: ets: use old 'nbands' while purging unused classes
 
   - xfrm:
     - restore GSO for SW crypto
     - bring back device check in validate_xmit_xfrm
 
   - tls: handle data disappearing from under the TLS ULP
 
   - ptp: prevent possible ABBA deadlock in ptp_clock_freerun()
 
   - eth: bnxt: fill data page pool with frags if PAGE_SIZE > BNXT_RX_PAGE_SIZE
 
   - eth: hv_netvsc: fix panic during namespace deletion with VF
 
 Previous releases - always broken:
 
   - netfilter: fix refcount leak on table dump
 
   - vsock: do not allow binding to VMADDR_PORT_ANY
 
   - sctp: linearize cloned gso packets in sctp_rcv
 
   - eth: hibmcge: fix the division by zero issue
 
   - eth: microchip: fix KSZ8863 reset problem
 
 Signed-off-by: Paolo Abeni <pabeni@redhat.com>
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Merge tag 'net-6.17-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

Pull networking fixes from Paolo Abeni:
 "Including fixes from Netfilter and IPsec.

  Current release - regressions:

   - netfilter: nft_set_pipapo:
      - don't return bogus extension pointer
      - fix null deref for empty set

  Current release - new code bugs:

   - core: prevent deadlocks when enabling NAPIs with mixed kthread
     config

   - eth: netdevsim: Fix wild pointer access in nsim_queue_free().

  Previous releases - regressions:

   - page_pool: allow enabling recycling late, fix false positive
     warning

   - sched: ets: use old 'nbands' while purging unused classes

   - xfrm:
      - restore GSO for SW crypto
      - bring back device check in validate_xmit_xfrm

   - tls: handle data disappearing from under the TLS ULP

   - ptp: prevent possible ABBA deadlock in ptp_clock_freerun()

   - eth:
      - bnxt: fill data page pool with frags if PAGE_SIZE > BNXT_RX_PAGE_SIZE
      - hv_netvsc: fix panic during namespace deletion with VF

  Previous releases - always broken:

   - netfilter: fix refcount leak on table dump

   - vsock: do not allow binding to VMADDR_PORT_ANY

   - sctp: linearize cloned gso packets in sctp_rcv

   - eth:
      - hibmcge: fix the division by zero issue
      - microchip: fix KSZ8863 reset problem"

* tag 'net-6.17-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (54 commits)
  net: usb: asix_devices: add phy_mask for ax88772 mdio bus
  net: kcm: Fix race condition in kcm_unattach()
  selftests: net/forwarding: test purge of active DWRR classes
  net/sched: ets: use old 'nbands' while purging unused classes
  bnxt: fill data page pool with frags if PAGE_SIZE > BNXT_RX_PAGE_SIZE
  netdevsim: Fix wild pointer access in nsim_queue_free().
  net: mctp: Fix bad kfree_skb in bind lookup test
  netfilter: nf_tables: reject duplicate device on updates
  ipvs: Fix estimator kthreads preferred affinity
  netfilter: nft_set_pipapo: fix null deref for empty set
  selftests: tls: test TCP stealing data from under the TLS socket
  tls: handle data disappearing from under the TLS ULP
  ptp: prevent possible ABBA deadlock in ptp_clock_freerun()
  ixgbe: prevent from unwanted interface name changes
  devlink: let driver opt out of automatic phys_port_name generation
  net: prevent deadlocks when enabling NAPIs with mixed kthread config
  net: update NAPI threaded config even for disabled NAPIs
  selftests: drv-net: don't assume device has only 2 queues
  docs: Fix name for net.ipv4.udp_child_hash_entries
  riscv: dts: thead: Add APB clocks for TH1520 GMACs
  ...
2025-08-14 07:14:30 -07:00
Shanker Donthineni 89a2d212bd dma/pool: Ensure DMA_DIRECT_REMAP allocations are decrypted
When CONFIG_DMA_DIRECT_REMAP is enabled, atomic pool pages are
remapped via dma_common_contiguous_remap() using the supplied
pgprot. Currently, the mapping uses
pgprot_dmacoherent(PAGE_KERNEL), which leaves the memory encrypted
on systems with memory encryption enabled (e.g., ARM CCA Realms).

This can cause the DMA layer to fail or crash when accessing the
memory, as the underlying physical pages are not configured as
expected.

Fix this by requesting a decrypted mapping in the vmap() call:
pgprot_decrypted(pgprot_dmacoherent(PAGE_KERNEL))

This ensures that atomic pool memory is consistently mapped
unencrypted.

Cc: stable@vger.kernel.org
Signed-off-by: Shanker Donthineni <sdonthineni@nvidia.com>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20250811181759.998805-1-sdonthineni@nvidia.com
2025-08-13 11:02:10 +02:00
John Stultz 21924af67d locking: Fix __clear_task_blocked_on() warning from __ww_mutex_wound() path
The __clear_task_blocked_on() helper added a number of sanity
checks ensuring we hold the mutex wait lock and that the task
we are clearing blocked_on pointer (if set) matches the mutex.

However, there is an edge case in the _ww_mutex_wound() logic
where we need to clear the blocked_on pointer for the task that
owns the mutex, not the task that is waiting on the mutex.

For this case the sanity checks aren't valid, so handle this
by allowing a NULL lock to skip the additional checks.

K Prateek Nayak and Maarten Lankhorst also pointed out that in
this case where we don't hold the owner's mutex wait_lock, we
need to be a bit more careful using READ_ONCE/WRITE_ONCE in both
the __clear_task_blocked_on() and __set_task_blocked_on()
implementations to avoid accidentally tripping WARN_ONs if two
instances race. So do that here as well.

This issue was easier to miss, I realized, as the test-ww_mutex
driver only exercises the wait-die class of ww_mutexes. I've
sent a patch[1] to address this so the logic will be easier to
test.

[1]: https://lore.kernel.org/lkml/20250801023358.562525-2-jstultz@google.com/

Fixes: a4f0b6fef4 ("locking/mutex: Add p->blocked_on wrappers for correctness checks")
Closes: https://lore.kernel.org/lkml/68894443.a00a0220.26d0e1.0015.GAE@google.com/
Reported-by: syzbot+602c4720aed62576cd79@syzkaller.appspotmail.com
Reported-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: John Stultz <jstultz@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Acked-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20250805001026.2247040-1-jstultz@google.com
2025-08-13 10:34:54 +02:00
Frederic Weisbecker c0a23bbc98 ipvs: Fix estimator kthreads preferred affinity
The estimator kthreads' affinity are defined by sysctl overwritten
preferences and applied through a plain call to the scheduler's affinity
API.

However since the introduction of managed kthreads preferred affinity,
such a practice shortcuts the kthreads core code which eventually
overwrites the target to the default unbound affinity.

Fix this with using the appropriate kthread's API.

Fixes: d1a8919758 ("kthread: Default affine kthread to its preferred NUMA node")
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Acked-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Florian Westphal <fw@strlen.de>
2025-08-13 08:34:33 +02:00
Andrea Righi ddf7233fca sched/ext: Fix invalid task state transitions on class switch
When enabling a sched_ext scheduler, we may trigger invalid task state
transitions, resulting in warnings like the following (which can be
easily reproduced by running the hotplug selftest in a loop):

 sched_ext: Invalid task state transition 0 -> 3 for fish[770]
 WARNING: CPU: 18 PID: 787 at kernel/sched/ext.c:3862 scx_set_task_state+0x7c/0xc0
 ...
 RIP: 0010:scx_set_task_state+0x7c/0xc0
 ...
 Call Trace:
  <TASK>
  scx_enable_task+0x11f/0x2e0
  switching_to_scx+0x24/0x110
  scx_enable.isra.0+0xd14/0x13d0
  bpf_struct_ops_link_create+0x136/0x1a0
  __sys_bpf+0x1edd/0x2c30
  __x64_sys_bpf+0x21/0x30
  do_syscall_64+0xbb/0x370
  entry_SYSCALL_64_after_hwframe+0x77/0x7f

This happens because we skip initialization for tasks that are already
dead (with their usage counter set to zero), but we don't exclude them
during the scheduling class transition phase.

Fix this by also skipping dead tasks during class swiching, preventing
invalid task state transitions.

Fixes: a8532fac7b ("sched_ext: TASK_DEAD tasks must be switched into SCX on ops_enable")
Cc: stable@vger.kernel.org # v6.12+
Signed-off-by: Andrea Righi <arighi@nvidia.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2025-08-11 06:56:37 -10:00
Waiman Long dfb36e4a8d futex: Use user_write_access_begin/_end() in futex_put_value()
Commit cec199c5e3 ("futex: Implement FUTEX2_NUMA") introduced the
futex_put_value() helper to write a value to the given user
address.

However, it uses user_read_access_begin() before the write. For
architectures that differentiate between read and write accesses, like
PowerPC, futex_put_value() fails with -EFAULT.

Fix that by using the user_write_access_begin/user_write_access_end() pair
instead.

Fixes: cec199c5e3 ("futex: Implement FUTEX2_NUMA")
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20250811141147.322261-1-longman@redhat.com
2025-08-11 17:53:21 +02:00
Oreoluwa Babatunde 2c223f7239 of: reserved_mem: Restructure call site for dma_contiguous_early_fixup()
Restructure the call site for dma_contiguous_early_fixup() to
where the reserved_mem nodes are being parsed from the DT so that
dma_mmu_remap[] is populated before dma_contiguous_remap() is called.

Fixes: 8a6e02d0c0 ("of: reserved_mem: Restructure how the reserved memory regions are processed")
Signed-off-by: Oreoluwa Babatunde <oreoluwa.babatunde@oss.qualcomm.com>
Tested-by: William Zhang <william.zhang@broadcom.com>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Link: https://lore.kernel.org/r/20250806172421.2748302-1-oreoluwa.babatunde@oss.qualcomm.com
2025-08-11 13:05:38 +02:00
Frederic Weisbecker 61399e0c54 rcu: Fix racy re-initialization of irq_work causing hangs
RCU re-initializes the deferred QS irq work everytime before attempting
to queue it. However there are situations where the irq work is
attempted to be queued even though it is already queued. In that case
re-initializing messes-up with the irq work queue that is about to be
handled.

The chances for that to happen are higher when the architecture doesn't
support self-IPIs and irq work are then all lazy, such as with the
following sequence:

1) rcu_read_unlock() is called when IRQs are disabled and there is a
   grace period involving blocked tasks on the node. The irq work
   is then initialized and queued.

2) The related tasks are unblocked and the CPU quiescent state
   is reported. rdp->defer_qs_iw_pending is reset to DEFER_QS_IDLE,
   allowing the irq work to be requeued in the future (note the previous
   one hasn't fired yet).

3) A new grace period starts and the node has blocked tasks.

4) rcu_read_unlock() is called when IRQs are disabled again. The irq work
   is re-initialized (but it's queued! and its node is cleared) and
   requeued. Which means it's requeued to itself.

5) The irq work finally fires with the tick. But since it was requeued
   to itself, it loops and hangs.

Fix this with initializing the irq work only once before the CPU boots.

Fixes: b41642c877 ("rcu: Fix rcu_read_unlock() deadloop due to IRQ work")
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202508071303.c1134cce-lkp@intel.com
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Joel Fernandes <joelagnelf@nvidia.com>
Signed-off-by: Neeraj Upadhyay (AMD) <neeraj.upadhyay@kernel.org>
2025-08-11 08:43:49 +05:30
Linus Torvalds b96ddbc5c8 - Remove an obsolete comment and fix spelling
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Merge tag 'smp_urgent_for_v6.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull smp fixes from Borislav Petkov:

 - Remove an obsolete comment and fix spelling

* tag 'smp_urgent_for_v6.17_rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  cpu: Remove obsolete comment from takedown_cpu()
  smp: Fix spelling in on_each_cpu_cond_mask()'s doc-comment
2025-08-10 08:51:37 +03:00