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authorWanpeng Li <wanpeng.li@hotmail.com>2016-08-04 09:42:20 +0800
committerIngo Molnar <mingo@kernel.org>2016-08-10 14:02:55 +0200
commitc0c8c9fa210c9a042060435f17e40ba4a76d6d6f (patch)
tree039bc9a7711ddf47c3c4a7afa324102030e791d4 /kernel
parent6075620b0590eaf22f10ce88833eb20a57f760d6 (diff)
downloadlinux-c0c8c9fa210c9a042060435f17e40ba4a76d6d6f.tar.bz2
sched/deadline: Fix lock pinning warning during CPU hotplug
The following warning can be triggered by hot-unplugging the CPU on which an active SCHED_DEADLINE task is running on: WARNING: CPU: 0 PID: 0 at kernel/locking/lockdep.c:3531 lock_release+0x690/0x6a0 releasing a pinned lock Call Trace: dump_stack+0x99/0xd0 __warn+0xd1/0xf0 ? dl_task_timer+0x1a1/0x2b0 warn_slowpath_fmt+0x4f/0x60 ? sched_clock+0x13/0x20 lock_release+0x690/0x6a0 ? enqueue_pushable_dl_task+0x9b/0xa0 ? enqueue_task_dl+0x1ca/0x480 _raw_spin_unlock+0x1f/0x40 dl_task_timer+0x1a1/0x2b0 ? push_dl_task.part.31+0x190/0x190 WARNING: CPU: 0 PID: 0 at kernel/locking/lockdep.c:3649 lock_unpin_lock+0x181/0x1a0 unpinning an unpinned lock Call Trace: dump_stack+0x99/0xd0 __warn+0xd1/0xf0 warn_slowpath_fmt+0x4f/0x60 lock_unpin_lock+0x181/0x1a0 dl_task_timer+0x127/0x2b0 ? push_dl_task.part.31+0x190/0x190 As per the comment before this code, its safe to drop the RQ lock here, and since we (potentially) change rq, unpin and repin to avoid the splat. Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com> [ Rewrote changelog. ] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Luca Abeni <luca.abeni@unitn.it> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1470274940-17976-1-git-send-email-wanpeng.li@hotmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/sched/deadline.c5
1 files changed, 4 insertions, 1 deletions
diff --git a/kernel/sched/deadline.c b/kernel/sched/deadline.c
index fcb7f0217ff4..1ce8867283dc 100644
--- a/kernel/sched/deadline.c
+++ b/kernel/sched/deadline.c
@@ -658,8 +658,11 @@ static enum hrtimer_restart dl_task_timer(struct hrtimer *timer)
*
* XXX figure out if select_task_rq_dl() deals with offline cpus.
*/
- if (unlikely(!rq->online))
+ if (unlikely(!rq->online)) {
+ lockdep_unpin_lock(&rq->lock, rf.cookie);
rq = dl_task_offline_migration(rq, p);
+ rf.cookie = lockdep_pin_lock(&rq->lock);
+ }
/*
* Queueing this task back might have overloaded rq, check if we need