This is a note to let you know that I've just added the patch titled
sched: Fix affine_move_task() self-concurrency
to the 5.11-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
sched-fix-affine_move_task-self-concurrency.patch
and it can be found in the queue-5.11 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 9e81889c7648d48dd5fe13f41cbc99f3c362484a Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Date: Wed, 24 Feb 2021 11:31:09 +0100
Subject: sched: Fix affine_move_task() self-concurrency
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
commit 9e81889c7648d48dd5fe13f41cbc99f3c362484a upstream.
Consider:
sched_setaffinity(p, X); sched_setaffinity(p, Y);
Then the first will install p->migration_pending = &my_pending; and
issue stop_one_cpu_nowait(pending); and the second one will read
p->migration_pending and _also_ issue: stop_one_cpu_nowait(pending),
the _SAME_ @pending.
This causes stopper list corruption.
Add set_affinity_pending::stop_pending, to indicate if a stopper is in
progress.
Fixes: 6d337eab041d ("sched: Fix migrate_disable() vs set_cpus_allowed_ptr()")
Cc: stable@xxxxxxxxxx
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx>
Reviewed-by: Valentin Schneider <valentin.schneider@xxxxxxx>
Link: https://lkml.kernel.org/r/20210224131355.649146419@xxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/sched/core.c | 15 ++++++++++++---
1 file changed, 12 insertions(+), 3 deletions(-)
--- a/kernel/sched/core.c
+++ b/kernel/sched/core.c
@@ -1864,6 +1864,7 @@ struct migration_arg {
struct set_affinity_pending {
refcount_t refs;
+ unsigned int stop_pending;
struct completion done;
struct cpu_stop_work stop_work;
struct migration_arg arg;
@@ -1982,12 +1983,15 @@ static int migration_cpu_stop(void *data
* determine is_migration_disabled() and so have to chase after
* it.
*/
+ WARN_ON_ONCE(!pending->stop_pending);
task_rq_unlock(rq, p, &rf);
stop_one_cpu_nowait(task_cpu(p), migration_cpu_stop,
&pending->arg, &pending->stop_work);
return 0;
}
out:
+ if (pending)
+ pending->stop_pending = false;
task_rq_unlock(rq, p, &rf);
if (complete)
@@ -2183,7 +2187,7 @@ static int affine_move_task(struct rq *r
int dest_cpu, unsigned int flags)
{
struct set_affinity_pending my_pending = { }, *pending = NULL;
- bool complete = false;
+ bool stop_pending, complete = false;
/* Can the task run on the task's current CPU? If so, we're done */
if (cpumask_test_cpu(task_cpu(p), &p->cpus_mask)) {
@@ -2256,14 +2260,19 @@ static int affine_move_task(struct rq *r
* anything else we cannot do is_migration_disabled(), punt
* and have the stopper function handle it all race-free.
*/
+ stop_pending = pending->stop_pending;
+ if (!stop_pending)
+ pending->stop_pending = true;
refcount_inc(&pending->refs); /* pending->{arg,stop_work} */
if (flags & SCA_MIGRATE_ENABLE)
p->migration_flags &= ~MDF_PUSH;
task_rq_unlock(rq, p, rf);
- stop_one_cpu_nowait(cpu_of(rq), migration_cpu_stop,
- &pending->arg, &pending->stop_work);
+ if (!stop_pending) {
+ stop_one_cpu_nowait(cpu_of(rq), migration_cpu_stop,
+ &pending->arg, &pending->stop_work);
+ }
if (flags & SCA_MIGRATE_ENABLE)
return 0;
Patches currently in stable-queue which might be from peterz@xxxxxxxxxxxxx are
queue-5.11/powerpc-perf-fix-handling-of-privilege-level-checks-in-perf-interrupt-context.patch
queue-5.11/sched-fix-migration_cpu_stop-requeueing.patch
queue-5.11/sched-simplify-set_affinity_pending-refcounts.patch
queue-5.11/perf-traceevent-ensure-read-cmdlines-are-null-terminated.patch
queue-5.11/perf-core-flush-pmu-internal-buffers-for-per-cpu-eve.patch
queue-5.11/sched-simplify-migration_cpu_stop.patch
queue-5.11/sched-membarrier-fix-missing-local-execution-of-ipi_sync_rq_state.patch
queue-5.11/x86-unwind-orc-disable-kasan-checking-in-the-orc-unwinder-part-2.patch
queue-5.11/arm64-perf-fix-64-bit-event-counter-read-truncation.patch
queue-5.11/sched-collate-affine_move_task-stoppers.patch
queue-5.11/sched-fix-affine_move_task-self-concurrency.patch
queue-5.11/stop_machine-mark-helpers-__always_inline.patch
queue-5.11/seqlock-lockdep-fix-seqcount_latch_init.patch
queue-5.11/sched-optimize-migration_cpu_stop.patch
queue-5.11/perf-build-fix-ccache-usage-in-cc-when-generating-arch-errno-table.patch
queue-5.11/mm-userfaultfd-fix-memory-corruption-due-to-writeprotect.patch
queue-5.11/perf-x86-intel-set-perf_attach_sched_cb-for-large-pe.patch
