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Juri Lelli
aee38ea954
dl_task_timer() is racy against several paths. Daniel noticed that the replenishment timer may experience a race condition against an enqueue_dl_entity() called from rt_mutex_setprio(). With his own words: rt_mutex_setprio() resets p->dl.dl_throttled. So the pattern is: start_dl_timer() throttled = 1, rt_mutex_setprio() throlled = 0, sched_switch() -> enqueue_task(), dl_task_timer-> enqueue_task() throttled is 0 => BUG_ON(on_dl_rq(dl_se)) fires as the scheduling entity is already enqueued on the -deadline runqueue. As we do for the other races, we just bail out in the replenishment timer code. Reported-by: Daniel Wagner <[email protected]> Tested-by: Daniel Wagner <[email protected]> Signed-off-by: Juri Lelli <[email protected]> Signed-off-by: Peter Zijlstra (Intel) <[email protected]> Cc: [email protected] Cc: Dario Faggioli <[email protected]> Cc: Michael Trimarchi <[email protected]> Cc: Fabio Checconi <[email protected]> Cc: Linus Torvalds <[email protected]> Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Ingo Molnar <[email protected]>