From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Sun, 20 Jan 2008 18:55:15 -0800 (PST) Received: from larry.melbourne.sgi.com (larry.melbourne.sgi.com [134.14.52.130]) by oss.sgi.com (8.12.11.20060308/8.12.11/SuSE Linux 0.7) with SMTP id m0L2t9EH030670 for ; Sun, 20 Jan 2008 18:55:11 -0800 Date: Mon, 21 Jan 2008 13:55:10 +1100 From: David Chinner Subject: Re: 2.6.24-rc8: possible circular locking dependency detected Message-ID: <20080121025510.GY155259@sgi.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: Christian Kujau Cc: xfs@oss.sgi.com, LKML , peterz@infradead.org, mingo@redhat.com On Fri, Jan 18, 2008 at 10:45:17PM +0100, Christian Kujau wrote: > Hi, > > just FYI, upgrading to -rc8 gave the following messages in kern.log in > the morning hours, when the backups were run: > > ======================================================= > [ INFO: possible circular locking dependency detected ] > 2.6.24-rc8 #2 > ------------------------------------------------------- > rsync/23295 is trying to acquire lock: > (iprune_mutex){--..}, at: [] shrink_icache_memory+0x72/0x220 > > but task is already holding lock: > (&(&ip->i_iolock)->mr_lock){----}, at: [] xfs_ilock+0x96/0xb0 > > which lock already depends on the new lock. memory reclaim can occur when an inode lock is held, causing i_iolock -> iprune_mutex to occur. This is quite common. During reclaim, while holding iprune_mutex, we lock a different inode to complete the cleaning up of it, resulting in iprune_mutex -> i_iolock. At this point, lockdep gets upset and blats out a warning. But, there's no problem here as it is always safe for us to take the i_iolock in inode reclaim because it can never be the same as the i_iolock that we've taken prior to memory reclaim being entered. Therefore false positive. Lockdep folk - we really need an annotation to prevent this false positive from being reported because we are getting reports at least once a week.... Cheers, Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group