From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wu Fengguang Subject: Re: [Bug 18632] "INFO: task" dpkg "blocked for more than 120 seconds. Date: Thu, 9 Jun 2011 11:54:26 +0800 Message-ID: <20110609035426.GA12061@localhost> References: <201106082138.p58Lchgj002615@demeter2.kernel.org> <20110608150241.8412a63d.akpm@linux-foundation.org> <20110609033217.GA10741@localhost> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Andrew Morton , Jan Kara , linux-fsdevel@vger.kernel.org, "bugzilla-daemon@bugzilla.kernel.org" , daaugusto@gmail.com, kernel-bugzilla@cygnusx-1.org, listposter@gmail.com, justincase@yopmail.com, clopez@igalia.com To: Dave Chinner , Christoph Hellwig Return-path: Received: from mga09.intel.com ([134.134.136.24]:63361 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756365Ab1FIDyc (ORCPT ); Wed, 8 Jun 2011 23:54:32 -0400 Content-Disposition: inline In-Reply-To: <20110609033217.GA10741@localhost> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Thu, Jun 09, 2011 at 11:32:17AM +0800, Wu Fengguang wrote: > On Thu, Jun 09, 2011 at 06:02:41AM +0800, Andrew Morton wrote: > > (udate by email because bugzilla is broken) > > > > On Wed, 8 Jun 2011 21:38:43 GMT > > bugzilla-daemon@bugzilla.kernel.org wrote: > > > > > https://bugzilla.kernel.org/show_bug.cgi?id=18632 > > > > I always get a bit worried when I see dm-crypt involved - it doesn't > > seem terribly well-behaved or reliable. > > > > That being said, some of the other reports here indicate that we are > > hitting a sync() livelock, sometimes fsync(). > > These comments all mention "blocked sync(1) on concurrent heavy writes". > > Comment #6 From Douglas Augusto > Comment #12 From Nathan Grennan > Comment #16 From justincase@yopmail.com > Comment #23 From Carlos Alberto Lopez Perez Oh it's not sync(1) in Carlos' case, but random commands like man/dd as well as task xfssyncd:451 blocked for more than 120 seconds. It looks more like XFS related livelock, because I ran into similar problem in a very simple XFS setup on some plain disk partition. Thanks, Fengguang > Comment #17 From Justin Wheeler is special in that fio is doing > read-only IO. Is it updating the mtime and the mtime writes are in > turn starved by the higher-priority continuous reads? (or at least the > write speed cannot keep up with the new mtime dirties) > > > A pile of patches from > > Wu Fengguang which could/should address these issues is about to hit > > the linux-next tree. > > Some livelock fixes will show up in tomorrow's linux-next tree. As for > now the fixes are available here: > > git://git.kernel.org/pub/scm/linux/kernel/git/wfg/writeback.git fs-writeback > > Thanks, > Fengguang