From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Chinner Subject: Re: 2.6.27-rc6: lockdep warning: iprune_mutex at shrink_icache_memory+0x38/0x1a8 Date: Tue, 16 Sep 2008 12:52:04 +1000 Message-ID: <20080916025204.GL5811@disturbed> References: <20080913233138.GA19576@orion> Mime-Version: 1.0 Return-path: Content-Disposition: inline In-Reply-To: <20080913233138.GA19576@orion> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Alexander Beregalov Cc: rjw@sisk.pl, linux-kernel@vger.kernel.org, kernel-testers@vger.kernel.org, linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com On Sun, Sep 14, 2008 at 03:31:38AM +0400, Alexander Beregalov wrote: > Hi > > [ INFO: possible circular locking dependency detected ] > 2.6.27-rc6-00034-gd1c6d2e #3 > ------------------------------------------------------- > nfsd/1766 is trying to acquire lock: > (iprune_mutex){--..}, at: [] shrink_icache_memory+0x38/0x1a8 > > but task is already holding lock: > (&(&ip->i_iolock)->mr_lock){----}, at: [] > xfs_ilock+0xa2/0xd6 > > > I read files through nfs and saw delay for few seconds. > System is x86_32, nfs, xfs. > The last working kernel is 2.6.27-rc5, > I do not know yet is it reproducible or not. We need a FAQ for this one. It's a false positive. Google for an explanation - I've explained it 4 or 5 times in the past year and asked that the lockdep folk invent a special annotation for the iprune_mutex (or memory reclaim) because of the way it can cause recursion into the filesystem and hence invert lock orders without causing deadlocks..... Cheers, Dave. -- Dave Chinner david@fromorbit.com