From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with ESMTP id 5311A6B01EF for ; Thu, 3 Jun 2010 02:52:58 -0400 (EDT) Date: Thu, 3 Jun 2010 02:52:52 -0400 From: Christoph Hellwig Subject: Re: [PATCH 02/17] xfs: skip writeback from reclaim context Message-ID: <20100603065252.GA28592@infradead.org> References: <20100531160727.842750532@bombadil.infradead.org> <20100531160859.184576507@bombadil.infradead.org> <20100602043957.GB7011@dastard> <20100602100812.GA25035@infradead.org> <20100602230209.GA27325@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100602230209.GA27325@dastard> Sender: owner-linux-mm@kvack.org To: Dave Chinner Cc: xfs@oss.sgi.com, linux-mm@kvack.org List-ID: On Thu, Jun 03, 2010 at 09:02:09AM +1000, Dave Chinner wrote: > Did you skip it unconditionally, or only when a transaction was > required? xfs_vm_releasepage is mostly a no-op if no transaction is required. If we have neither delalloc nor unwritten buffer we do not actually enter xfs_page_state_convert, and ->releasepage also doesn't touch unampped buffers at all. > The scary part is that I've seen stack traces (i.e. most stack used) > through this reclaim path for delalloc conversion even for > allocations that are GFP_NOFS and the only thing saving us from > deadlocks is th PF_FSTRANS check. Even worse is that > shrinker_page_list() will call try_to_release_pages() without > checking whether it's allowed to enter the filesystem or not, so we > can be doing block allocation in places we've specifically told the > memory allocation subsystem not to.... s/shrinker_page_list/shrink_page_list/ and s/try_to_release_pages/try_to_release_page/ above. shrink_page_list takes the gfp_mask for try_to_release_page from the scan_control structure passed to it from all the top of the long callchain. I can't find anobvious bug, but this could cause a lot more harm. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org