From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757559Ab0AOMxb (ORCPT ); Fri, 15 Jan 2010 07:53:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757407Ab0AOMxa (ORCPT ); Fri, 15 Jan 2010 07:53:30 -0500 Received: from casper.infradead.org ([85.118.1.10]:33125 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752578Ab0AOMxa (ORCPT ); Fri, 15 Jan 2010 07:53:30 -0500 Subject: Re: lockdep: inconsistent {RECLAIM_FS-ON-W} -> {IN-RECLAIM_FS-R} usage. From: Peter Zijlstra To: Dave Chinner Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, Christoph Hellwig , Nick Piggin In-Reply-To: <20100115124410.GI28498@discord.disaster> References: <20100115120253.GH28498@discord.disaster> <1263557473.4244.399.camel@laptop> <20100115124410.GI28498@discord.disaster> Content-Type: text/plain; charset="UTF-8" Date: Fri, 15 Jan 2010 13:53:15 +0100 Message-ID: <1263559995.4244.403.camel@laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2010-01-15 at 23:44 +1100, Dave Chinner wrote: > > > > I can't work out what the RECLAIM_FS notations are > > > supposed to mean from the code and they are not documented at > > > all, so I need someone to explain what this means before I can > > > determine if it is a valid warning or not.... > > > > The RECLAIM_FS bit means that lock (iprune_sem) was > > taken from reclaim and is also taken over an allocation. > > So there's an implicit, undocumented requirement that inode reclaim > during unmount requires a filesystem to do GFP_NOFS allocation? Well, I don't know enough about xfs (of filesystems in generic) to say that with any certainty, but I can imagine inode writeback from the sync that goes with umount to cause issues. If this inode reclaim is past all that and the filesystem is basically RO, then I don't think so and this could be considered a false positive, in which case we need an annotation for this. I added hch since he poked at similar reclaim recursions on XFS before and Nick since he thought up this annotation and knows more about filesystems than I do.