From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail143.messagelabs.com (mail143.messagelabs.com [216.82.254.35]) by kanga.kvack.org (Postfix) with ESMTP id A531A6B01D9 for ; Fri, 11 Jun 2010 12:29:17 -0400 (EDT) Date: Fri, 11 Jun 2010 12:29:12 -0400 From: Christoph Hellwig Subject: Re: [RFC PATCH 0/6] Do not call ->writepage[s] from direct reclaim and use a_ops->writepages() where possible Message-ID: <20100611162912.GC24707@infradead.org> References: <1275987745-21708-1-git-send-email-mel@csn.ul.ie> <20100608090811.GA5949@infradead.org> <20100608092814.GB27717@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100608092814.GB27717@csn.ul.ie> Sender: owner-linux-mm@kvack.org To: Mel Gorman Cc: Christoph Hellwig , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Dave Chinner , Chris Mason , Nick Piggin , Rik van Riel List-ID: On Tue, Jun 08, 2010 at 10:28:14AM +0100, Mel Gorman wrote: > > - we also need to care about ->releasepage. At least for XFS it > > can end up in the same deep allocator chain as ->writepage because > > it does all the extent state conversions, even if it doesn't > > start I/O. > > Dang. > > > I haven't managed yet to decode the ext4/btrfs codepaths > > for ->releasepage yet to figure out how they release a page that > > covers a delayed allocated or unwritten range. > > > > If ext4/btrfs are also very deep call-chains and this series is going more > or less the right direction, then avoiding calling ->releasepage from direct > reclaim is one, somewhat unfortunate, option. The second is to avoid it on > a per-filesystem basis for direct reclaim using PF_MEMALLOC to detect > reclaimers and PF_KSWAPD to tell the difference between direct > reclaimers and kswapd. I went throught this a bit more and I can't actually hit that code in XFS ->releasepage anymore. I've also audited the caller and can't see how we could theoretically hit it anymore. Do the VM gurus know a case where we would call ->releasepage on a page that's actually dirty and hasn't been through block_invalidatepage before? -- 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