diff options
| author | Thomas Gleixner <tglx@linutronix.de> | 2021-08-28 15:55:52 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-09-18 13:43:24 +0200 |
| commit | 5b7992c06c54f76f71ff5fa0135a80bc41153689 (patch) | |
| tree | 83b0d5d168265b48efafaf8ffbd35f10cbe18261 /kernel | |
| parent | c541a5ef20aa9352c6d7cd9863bfb650293a5192 (diff) | |
sched: Prevent balance_push() on remote runqueues
commit 868ad33bfa3bf39960982682ad3a0f8ebda1656e upstream.
sched_setscheduler() and rt_mutex_setprio() invoke the run-queue balance
callback after changing priorities or the scheduling class of a task. The
run-queue for which the callback is invoked can be local or remote.
That's not a problem for the regular rq::push_work which is serialized with
a busy flag in the run-queue struct, but for the balance_push() work which
is only valid to be invoked on the outgoing CPU that's wrong. It not only
triggers the debug warning, but also leaves the per CPU variable push_work
unprotected, which can result in double enqueues on the stop machine list.
Remove the warning and validate that the function is invoked on the
outgoing CPU.
Fixes: ae7927023243 ("sched: Optimize finish_lock_switch()")
Reported-by: Sebastian Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/87zgt1hdw7.ffs@tglx
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/core.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index a2403432f3ab..399c37c95392 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -8536,7 +8536,6 @@ static void balance_push(struct rq *rq) struct task_struct *push_task = rq->curr; lockdep_assert_rq_held(rq); - SCHED_WARN_ON(rq->cpu != smp_processor_id()); /* * Ensure the thing is persistent until balance_push_set(.on = false); @@ -8544,9 +8543,10 @@ static void balance_push(struct rq *rq) rq->balance_callback = &balance_push_callback; /* - * Only active while going offline. + * Only active while going offline and when invoked on the outgoing + * CPU. */ - if (!cpu_dying(rq->cpu)) + if (!cpu_dying(rq->cpu) || rq != this_rq()) return; /* |