Thomas Gleixner 868ad33bfa sched: Prevent balance_push() on remote runqueues
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: ae79270232 ("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
2021-09-09 11:27:23 +02:00
2021-08-15 13:40:53 -10:00

Linux kernel
============

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