Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933505AbaDBWsv (ORCPT ); Wed, 2 Apr 2014 18:48:51 -0400 Received: from mx1.redhat.com ([209.132.183.28]:54078 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932414AbaDBWst (ORCPT ); Wed, 2 Apr 2014 18:48:49 -0400 Date: Wed, 2 Apr 2014 18:48:40 -0400 From: Dave Jones To: "Paul E. McKenney" Cc: Linux Kernel Subject: Re: rcu_prempt stalls / lockup Message-ID: <20140402224840.GA5385@redhat.com> Mail-Followup-To: Dave Jones , "Paul E. McKenney" , Linux Kernel References: <20140331232220.GP4284@linux.vnet.ibm.com> <20140331233552.GB30019@redhat.com> <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> <20140402162043.GA11090@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140402162043.GA11090@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Hrmph. $ git bisect bad The merge base 5cb480f6b488128140c940abff3c36f524a334a8 is bad. This means the bug has been fixed between 5cb480f6b488128140c940abff3c36f524a334a8 and [455c6fdbd219161bd09b1165f11699d6d73de11c 62c206bd514600d4d73751ade00dca8e488390a3 e086481baf9d0436bdd6e9b739bfa4a83fb89ef5]. Not sure where to go from here.. The 'good' news is I can reproduce it pretty reliably now. I start my fuzz tester, and immediately do a git diff in my working tree, and then boom.. Dave -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/