Commit d7921a5d authored Mar 16, 2017 by Wanpeng Li Committed by Ingo Molnar Mar 23, 2017

sched/core: Fix rq lock pinning warning after call balance callbacks



This can be reproduced by running rt-migrate-test:

 WARNING: CPU: 2 PID: 2195 at kernel/locking/lockdep.c:3670 lock_unpin_lock()
 unpinning an unpinned lock
 ...
 Call Trace:
  dump_stack()
  __warn()
  warn_slowpath_fmt()
  lock_unpin_lock()
  __balance_callback()
  __schedule()
  schedule()
  futex_wait_queue_me()
  futex_wait()
  do_futex()
  SyS_futex()
  do_syscall_64()
  entry_SYSCALL64_slow_path()

Revert the rq_lock_irqsave() usage here, the whole point of the
balance_callback() was to allow dropping rq->lock.

Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Signed-off-by: Wanpeng Li <wanpeng.li@hotmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 8a8c69c3 ("sched/core: Add rq->lock wrappers")
Link: http://lkml.kernel.org/r/1489718719-3951-1-git-send-email-wanpeng.li@hotmail.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 15ff991e

kernel/sched/core.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -2776,9 +2776,9 @@ static void __balance_callback(struct rq *rq)
		{
		struct callback_head head, next;
		void (func)(struct rq rq);
		struct rq_flags rf;
		unsigned long flags;

		rq_lock_irqsave(rq, &rf);
		raw_spin_lock_irqsave(&rq->lock, flags);
		head = rq->balance_callback;
		rq->balance_callback = NULL;
		while (head) {
		@@ -2789,7 +2789,7 @@ static void __balance_callback(struct rq *rq)

		func(rq);
		}
		rq_unlock_irqrestore(rq, &rf);
		raw_spin_unlock_irqrestore(&rq->lock, flags);
		}

		static inline void balance_callback(struct rq *rq)

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