Re: rcu_prempt stalls / lockup

From: Dave Jones
Date: Wed Apr 02 2014 - 12:23:48 EST


On Wed, Apr 02, 2014 at 09:20:43AM -0700, Paul E. McKenney wrote:
> On Tue, Apr 01, 2014 at 11:32:45AM -0700, Paul E. McKenney wrote:
> > On Tue, Apr 01, 2014 at 02:04:14PM -0400, Dave Jones wrote:
> > > On Tue, Apr 01, 2014 at 10:55:45AM -0700, Paul E. McKenney wrote:
>
> [ . . . ]
>
> > > > Waiting uninterruptibly. Presumably blocked on mutex_lock(). But
> > > > you have CONFIG_PROVE_LOCKING(), so any deadlocks should have been
> > > > reported.
> > >
> > > Lockdep had reported something a little earlier (timestamped at 1108.xxxxxx)
> > > but that's a known false-positive in xfs.
> >
> > Yep, I would be very surprised if that was related to the grace-period hang.
>
> Ah, but it could be suppressing later lockdep splats. So if this can be
> reproduced without xfs, we might get additional information from lockdep.

Hmm, I lack another test machine, and don't really feel like reinstalling it right now.
I'm halfway through a bisect, hopefully that's fruitful.

Dave

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