From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030687AbaDJWwn (ORCPT ); Thu, 10 Apr 2014 18:52:43 -0400 Received: from ipmail04.adl6.internode.on.net ([150.101.137.141]:22351 "EHLO ipmail04.adl6.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030537AbaDJWwi (ORCPT ); Thu, 10 Apr 2014 18:52:38 -0400 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AkxaAOsfR1N5LEcvPGdsb2JhbABagwaIWbcNhV2BIxcDAQEBATg1giUBAQEEOhwjEAgDGAklDwUlAwcaE4d7zGgXFo5WB4MkgRQEmF2KZIshKw Date: Fri, 11 Apr 2014 08:52:34 +1000 From: Dave Chinner To: Sasha Levin Cc: Al Viro , Dave Jones , Linux Kernel , xfs@oss.sgi.com Subject: Re: xfs i_lock vs mmap_sem lockdep trace. Message-ID: <20140410225234.GF27519@dastard> References: <20140329223109.GA24098@redhat.com> <20140330234335.GB16336@dastard> <20140330235717.GO18016@ZenIV.linux.org.uk> <20140331004053.GA17603@dastard> <53445EC0.9060707@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <53445EC0.9060707@oracle.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 Tue, Apr 08, 2014 at 04:40:32PM -0400, Sasha Levin wrote: > On 03/30/2014 08:40 PM, Dave Chinner wrote: > > On Mon, Mar 31, 2014 at 12:57:17AM +0100, Al Viro wrote: > >> > On Mon, Mar 31, 2014 at 10:43:35AM +1100, Dave Chinner wrote: > >>> > > filldir on a directory inode vs page fault on regular file. Known > >>> > > issue, definitely a false positive. 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... > >> > > >> > Give i_lock on directories a separate class, as it's been done for i_mutex... > > Already done that. Commit: > > > > 93a8614 xfs: fix directory inode iolock lockdep false positive > > Hi Dave, > > The commit above introduces a new lockdep issue for me: Right, it's fixed one class of false positive which uncovers the next class of false positive. lockdep gives me the shits at times because every time we make some obviously correct locking change to the XFS inodes we then spend the next 3-4 kernel releases chasing down and annotating locks so that lockdep doesn't throw false positives everywhere. It's on my queue of things to fix but, quite frankly, lockdep false positives are low priority to fix right now. Cheers, Dave. -- Dave Chinner david@fromorbit.com From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay2.corp.sgi.com [137.38.102.29]) by oss.sgi.com (Postfix) with ESMTP id 312767F56 for ; Thu, 10 Apr 2014 17:52:39 -0500 (CDT) Received: from cuda.sgi.com (cuda2.sgi.com [192.48.176.25]) by relay2.corp.sgi.com (Postfix) with ESMTP id 092A3304059 for ; Thu, 10 Apr 2014 15:52:38 -0700 (PDT) Received: from ipmail04.adl6.internode.on.net (ipmail04.adl6.internode.on.net [150.101.137.141]) by cuda.sgi.com with ESMTP id f1f8piuPlRz1u3xg for ; Thu, 10 Apr 2014 15:52:37 -0700 (PDT) Date: Fri, 11 Apr 2014 08:52:34 +1000 From: Dave Chinner Subject: Re: xfs i_lock vs mmap_sem lockdep trace. Message-ID: <20140410225234.GF27519@dastard> References: <20140329223109.GA24098@redhat.com> <20140330234335.GB16336@dastard> <20140330235717.GO18016@ZenIV.linux.org.uk> <20140331004053.GA17603@dastard> <53445EC0.9060707@oracle.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <53445EC0.9060707@oracle.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Sasha Levin Cc: Dave Jones , xfs@oss.sgi.com, Al Viro , Linux Kernel On Tue, Apr 08, 2014 at 04:40:32PM -0400, Sasha Levin wrote: > On 03/30/2014 08:40 PM, Dave Chinner wrote: > > On Mon, Mar 31, 2014 at 12:57:17AM +0100, Al Viro wrote: > >> > On Mon, Mar 31, 2014 at 10:43:35AM +1100, Dave Chinner wrote: > >>> > > filldir on a directory inode vs page fault on regular file. Known > >>> > > issue, definitely a false positive. 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... > >> > > >> > Give i_lock on directories a separate class, as it's been done for i_mutex... > > Already done that. Commit: > > > > 93a8614 xfs: fix directory inode iolock lockdep false positive > > Hi Dave, > > The commit above introduces a new lockdep issue for me: Right, it's fixed one class of false positive which uncovers the next class of false positive. lockdep gives me the shits at times because every time we make some obviously correct locking change to the XFS inodes we then spend the next 3-4 kernel releases chasing down and annotating locks so that lockdep doesn't throw false positives everywhere. It's on my queue of things to fix but, quite frankly, lockdep false positives are low priority to fix right now. Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs