From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Chinner Subject: Re: xfstests 073 regression Date: Tue, 2 Aug 2011 22:04:45 +1000 Message-ID: <20110802120445.GF12870@dastard> References: <20110730134422.GA1884@infradead.org> <20110731151014.GA23106@localhost> <20110731234749.GQ5404@dastard> <20110801012813.GR5404@dastard> <20110801020951.GA12870@dastard> <20110801112330.GA27190@infradead.org> <20110801165242.GA18802@infradead.org> <20110802114428.GA6014@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Christoph Hellwig , Linus Torvalds , Jan Kara , Andrew Morton , "linux-fsdevel@vger.kernel.org" , LKML To: Wu Fengguang Return-path: Received: from ipmail06.adl2.internode.on.net ([150.101.137.129]:28956 "EHLO ipmail06.adl2.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754120Ab1HBMEv (ORCPT ); Tue, 2 Aug 2011 08:04:51 -0400 Content-Disposition: inline In-Reply-To: <20110802114428.GA6014@localhost> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Tue, Aug 02, 2011 at 07:44:28PM +0800, Wu Fengguang wrote: > On Tue, Aug 02, 2011 at 12:52:42AM +0800, Christoph Hellwig wrote: > > wb_check_background_flush is indeed what we're hitting. > > That means s_umount is NOT held by another queued writeback work. Right. We already kind of knew that was ocurring because there's a remount,ro going on. > > > See the trace output using a patch inspired by Curt's below: > > > > # tracer: nop > > # > > # TASK-PID CPU# TIMESTAMP FUNCTION > > # | | | | | > > <...>-4279 [000] 113.034052: writeback_grab_super_failed: bdi 7:0: sb_dev 0:0 nr_pages=9223372036854775807 sync_mode=0 kupdate=0 range_cyclic=1 background=1 reason=wb_check_background_flush > > <...>-4279 [000] 113.034052: writeback_grab_super_failed: bdi 7:0: sb_dev 0:0 nr_pages=9223372036854775807 sync_mode=0 kupdate=0 range_cyclic=1 background=1 reason=wb_check_background_flush > > <...>-4279 [000] 113.034052: writeback_grab_super_failed: bdi 7:0: sb_dev 0:0 nr_pages=9223372036854775807 sync_mode=0 kupdate=0 range_cyclic=1 background=1 reason=wb_check_background_flush > > What's that bdi 7:0? And sb_dev=0:0, nr_pages=9223372036854775807=0x7fffffffffffffff. > > All are indicating some special bdi/inode. #define LOOP_MAJOR 7 It's a loop device. xfstests uses them quite a lot. Maybe it would be a good idea to run xfstests on an xfs filesystem in your regular writeback testing cycle to get decent coverage of this case? Cheers, Dave. -- Dave Chinner david@fromorbit.com