Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753877Ab0GFPZ7 (ORCPT ); Tue, 6 Jul 2010 11:25:59 -0400 Received: from gir.skynet.ie ([193.1.99.77]:33115 "EHLO gir.skynet.ie" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751088Ab0GFPZ6 (ORCPT ); Tue, 6 Jul 2010 11:25:58 -0400 Date: Tue, 6 Jul 2010 16:25:39 +0100 From: Mel Gorman To: Minchan Kim Cc: KOSAKI Motohiro , Andrew Morton , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Dave Chinner , Chris Mason , Nick Piggin , Rik van Riel , Johannes Weiner , Christoph Hellwig , KAMEZAWA Hiroyuki , Andrea Arcangeli Subject: Re: [PATCH 12/14] vmscan: Do not writeback pages in direct reclaim Message-ID: <20100706152539.GG13780@csn.ul.ie> References: <20100702125155.69c02f85.akpm@linux-foundation.org> <20100705134949.GC13780@csn.ul.ie> <20100706093529.CCD1.A69D9226@jp.fujitsu.com> <20100706101235.GE13780@csn.ul.ie> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1886 Lines: 53 On Tue, Jul 06, 2010 at 08:24:57PM +0900, Minchan Kim wrote: > Hi, Mel. > > On Tue, Jul 6, 2010 at 7:12 PM, Mel Gorman wrote: > > On Tue, Jul 06, 2010 at 09:36:41AM +0900, KOSAKI Motohiro wrote: > >> Hello, > >> > >> > Ok, that's reasonable as I'm still working on that patch. For example, the > >> > patch disabled anonymous page writeback which is unnecessary as the stack > >> > usage for anon writeback is less than file writeback. > >> > >> How do we examine swap-on-file? > >> > > > > Anything in particular wrong with the following? > > > > /* > > ?* For now, only kswapd can writeback filesystem pages as otherwise > > ?* there is a stack overflow risk > > ?*/ > > static inline bool reclaim_can_writeback(struct scan_control *sc, > > ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?struct page *page) > > { > > ? ? ? ?return !page_is_file_cache(page) || current_is_kswapd(); > > } > > > > Even if it is a swapfile, I didn't spot a case where the filesystems > > writepage would be called. Did I miss something? > > > As I understand Kosaki's opinion, He said that if we make swapout in > pageout, it isn't a problem in case of swap device since swapout of > block device is light Sure > but it is still problem in case of swap file. > That's because swapout on swapfile cause file system writepage which > makes kernel stack overflow. > I don't *think* this is a problem unless I missed where writing out to swap enters teh filesystem code. I'll double check. -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/