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| author | Sebastian Andrzej Siewior <bigeasy@linutronix.de> | 2019-08-16 18:06:26 +0200 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-09-10 10:35:19 +0100 |
| commit | 9ad89d579c01cc6449d4fc503f00914caa4bcc7e (patch) | |
| tree | fbc95b253459386f8a7e03ef6fed5b8d194681ca /kernel | |
| parent | 086ddc5e71721ce385382e926b8112148c2ad58a (diff) | |
| download | linux-stable-9ad89d579c01cc6449d4fc503f00914caa4bcc7e.tar.gz linux-stable-9ad89d579c01cc6449d4fc503f00914caa4bcc7e.tar.bz2 linux-stable-9ad89d579c01cc6449d4fc503f00914caa4bcc7e.zip | |
sched/core: Schedule new worker even if PI-blocked
[ Upstream commit b0fdc01354f45d43f082025636ef808968a27b36 ]
If a task is PI-blocked (blocking on sleeping spinlock) then we don't want to
schedule a new kworker if we schedule out due to lock contention because !RT
does not do that as well. A spinning spinlock disables preemption and a worker
does not schedule out on lock contention (but spin).
On RT the RW-semaphore implementation uses an rtmutex so
tsk_is_pi_blocked() will return true if a task blocks on it. In this case we
will now start a new worker which may deadlock if one worker is waiting on
progress from another worker. Since a RW-semaphore starts a new worker on !RT,
we should do the same on RT.
XFS is able to trigger this deadlock.
Allow to schedule new worker if the current worker is PI-blocked.
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/20190816160626.12742-1-bigeasy@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/sched/core.c | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 4d5962232a55..42bc2986520d 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3469,7 +3469,7 @@ void __noreturn do_task_dead(void) static inline void sched_submit_work(struct task_struct *tsk) { - if (!tsk->state || tsk_is_pi_blocked(tsk)) + if (!tsk->state) return; /* @@ -3485,6 +3485,9 @@ static inline void sched_submit_work(struct task_struct *tsk) preempt_enable_no_resched(); } + if (tsk_is_pi_blocked(tsk)) + return; + /* * If we are going to sleep and we have plugged IO queued, * make sure to submit it to avoid deadlocks. |