Hi Sebastian, On Thu, 8 Dec 2016 14:33:06 +0100, Sebastian Andrzej Siewior wrote: > On 2016-12-08 12:20:28 [+0000], John Keeping wrote: > > I am seeing the following splat when stopping btattach on v4.4.30-rt41 > > with PREEMPT_RT_FULL with lockdep and slub_debug. > > > > The bad unlock balance seems to just be an effect of the lock having > > been overwritten with POISON_FREE, the real issue is that > > put_pwq_unlocked() is not resuming and unlocking the pool before the RCU > > work scheduled indirectly by put_pwq() has completed. > > can you reproduce this? If so, is this patch helping? Yes, I am able to reproduce it reasonably reliably, or at least I *was* able to: since applying the patch below I haven't seen it fail at all, so consider the patch: Tested-by: John Keeping <john@xxxxxxxxxxxx> > diff --git a/kernel/workqueue.c b/kernel/workqueue.c > --- a/kernel/workqueue.c > +++ b/kernel/workqueue.c > @@ -1135,9 +1135,11 @@ static void put_pwq_unlocked(struct pool_workqueue *pwq) > * As both pwqs and pools are RCU protected, the > * following lock operations are safe. > */ > + rcu_read_lock(); > local_spin_lock_irq(pendingb_lock, &pwq->pool->lock); > put_pwq(pwq); > local_spin_unlock_irq(pendingb_lock, &pwq->pool->lock); > + rcu_read_unlock(); > } > } John -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
