From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754631AbaCaAUp (ORCPT ); Sun, 30 Mar 2014 20:20:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36155 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753422AbaCaAUm (ORCPT ); Sun, 30 Mar 2014 20:20:42 -0400 Date: Sun, 30 Mar 2014 20:20:30 -0400 From: Dave Jones To: Dave Chinner Cc: Linux Kernel , xfs@oss.sgi.com Subject: Re: xfs i_lock vs mmap_sem lockdep trace. Message-ID: <20140331002030.GA19391@redhat.com> Mail-Followup-To: Dave Jones , Dave Chinner , Linux Kernel , xfs@oss.sgi.com References: <20140329223109.GA24098@redhat.com> <20140330234335.GB16336@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20140330234335.GB16336@dastard> 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 Mon, Mar 31, 2014 at 10:43:35AM +1100, Dave Chinner wrote: > On Sat, Mar 29, 2014 at 06:31:09PM -0400, Dave Jones wrote: > > Not sure if I've reported this already (it looks familiar, though I've not managed > > to find it in my sent mail folder). This is rc8 + a diff to fix the stack usage reports > > I was seeing (diff at http://paste.fedoraproject.org/89854/13210913/raw) > > > > ====================================================== > > [ INFO: possible circular locking dependency detected ] > > 3.14.0-rc8+ #153 Not tainted > > ------------------------------------------------------- > > git/32710 is trying to acquire lock: > > (&(&ip->i_lock)->mr_lock){++++.+}, at: [] xfs_ilock+0x122/0x250 [xfs] > > > > but task is already holding lock: > > (&mm->mmap_sem){++++++}, at: [] __do_page_fault+0x14a/0x610 > > > > which lock already depends on the new lock. > > filldir on a directory inode vs page fault on regular file. Known > issue, definitely a false positive. ah yeah, thought it looked familiar. I think I reported this last summer. > We have to change locking > algorithms to avoid such deficiencies of lockdep (a case of "lockdep > considered harmful", perhaps?) so it's not something I'm about to > rush... Bummer, as it makes lockdep useless on my test box using xfs because it disables itself after hitting this very quickly. (I re-enabled it a couple days ago wondering why I'd left it turned off, chances are it was because of this) Dave