Date: Wed, 2 Apr 2014 09:20:43 -0700
From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Dave Jones <davej@redhat.com>, Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: rcu_prempt stalls / lockup
Message-ID: <20140402162043.GA11090@linux.vnet.ibm.com>
Reply-To: paulmck@linux.vnet.ibm.com
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 <20140401004801.GQ4284@linux.vnet.ibm.com>
 <20140401150849.GA14757@redhat.com>
 <20140401153032.GT4284@linux.vnet.ibm.com>
 <20140401172244.GA10363@redhat.com>
 <20140401175545.GV4284@linux.vnet.ibm.com>
 <20140401180414.GA12326@redhat.com>
 <20140401183245.GA12473@linux.vnet.ibm.com>
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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.

							Thanx, Paul

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