From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: with ECARTIS (v1.0.0; list xfs); Wed, 24 Jan 2007 16:06:38 -0800 (PST) Received: from smtp107.mail.mud.yahoo.com (smtp107.mail.mud.yahoo.com [209.191.85.217]) by oss.sgi.com (8.12.10/8.12.10/SuSE Linux 0.7) with SMTP id l0P06Tqw020608 for ; Wed, 24 Jan 2007 16:06:30 -0800 Message-ID: <45B7F43B.9060905@yahoo.com.au> Date: Thu, 25 Jan 2007 11:05:15 +1100 From: Nick Piggin MIME-Version: 1.0 Subject: Re: [PATCH 1/2]: Fix BUG in cancel_dirty_pages on XFS References: <20070123223702.GF33919298@melbourne.sgi.com> <1169640835.6189.14.camel@twins> <45B7627B.8050202@yahoo.com.au> <1169649604.6189.27.camel@twins> In-Reply-To: <1169649604.6189.27.camel@twins> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: xfs-bounce@oss.sgi.com Errors-to: xfs-bounce@oss.sgi.com List-Id: xfs To: Peter Zijlstra Cc: David Chinner , linux-kernel@vger.kernel.org, xfs@oss.sgi.com, akpm@osdl.org Peter Zijlstra wrote: > On Thu, 2007-01-25 at 00:43 +1100, Nick Piggin wrote: > > >>>Have you seen the new launder_page() a_op? called from >>>invalidate_inode_pages2_range() >> >>It would have been nice to make that one into a more potentially >>useful generic callback. > > > That can still be done when the need arises, right? Yeah I guess so. >>But why was it introduced, exactly? I can't tell from the code or >>the discussion why NFS couldn't start the IO, and signal the caller >>to wait_on_page_writeback and retry? That seemed to me like the >>convetional fix. > > > to quote a bit: > > On Tue, 19 Dec 2006 18:19:38 -0500 > Trond Myklebust wrote: > > >> NFS: Fix race in nfs_release_page() >> >> invalidate_inode_pages2() may set the dirty bit on a page owing to the call >> to unmap_mapping_range() after the page was locked. In order to fix this, >> NFS has hooked the releasepage() method. This, however leads to deadlocks >> in other parts of the VM. > > > and: > > >>>Now, arguably the VM shouldn't be calling try_to_release_page() with >>>__GFP_FS when it's holding a lock on a page. >>> >>>But otoh, NFS should never be running lock_page() within nfs_release_page() >>>against the page which was passed into nfs_release_page(). It'll deadlock >>>for sure. >> >>The reason why it is happening is that the last dirty page from that >>inode gets cleaned, resulting in a call to dput(). OK but what's the problem with just failing to release the page if it is dirty, I wonder? In the worst case, page reclaim will just end up doing a writeout to clean it. -- SUSE Labs, Novell Inc. Send instant messages to your online friends http://au.messenger.yahoo.com