From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by oss.sgi.com (8.14.3/8.14.3/SuSE Linux 0.8) with ESMTP id o524bYWV048106 for ; Tue, 1 Jun 2010 23:37:34 -0500 Received: from mail.internode.on.net (localhost [127.0.0.1]) by cuda.sgi.com (Spam Firewall) with ESMTP id 3B533130D504 for ; Tue, 1 Jun 2010 21:42:21 -0700 (PDT) Received: from mail.internode.on.net (bld-mail18.adl2.internode.on.net [150.101.137.103]) by cuda.sgi.com with ESMTP id CrTToBZTKCUzkyGp for ; Tue, 01 Jun 2010 21:42:21 -0700 (PDT) Date: Wed, 2 Jun 2010 14:39:57 +1000 From: Dave Chinner Subject: Re: [PATCH 02/17] xfs: skip writeback from reclaim context Message-ID: <20100602043957.GB7011@dastard> References: <20100531160727.842750532@bombadil.infradead.org> <20100531160859.184576507@bombadil.infradead.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20100531160859.184576507@bombadil.infradead.org> 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 Sender: xfs-bounces@oss.sgi.com Errors-To: xfs-bounces@oss.sgi.com To: Christoph Hellwig Cc: xfs@oss.sgi.com On Mon, May 31, 2010 at 12:07:29PM -0400, Christoph Hellwig wrote: > Allowing writeback from reclaim context causes massive problems with stack > overflows as we can call into the writeback code which tends to be a heavy > stack user both in the generic code and XFS from random contexts that > perform memory allocations. > > Follow the example of btrfs (and in slightly different form ext4) and refuse > to write out data from reclaim context. This issue should really be handled > by the VM so that we can tune better for this case, but until we get it > sorted out there we have to hack around this in each filesystem with a > complex writeback path. > > Signed-off-by: Christoph Hellwig Yup, I agree that we have to do this for the moment. It hasn't caused any problems in my usual OOM testing, so it seems safe to do. Reviewed-by: Dave Chinner Also worth thinking about is if should be checked in xfs_vm_releasepage() as well to avoid the same stack issues if it triggers allocation... Cheers, Dave. -- Dave Chinner david@fromorbit.com _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs