Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755688Ab0GGBOt (ORCPT ); Tue, 6 Jul 2010 21:14:49 -0400 Received: from bombadil.infradead.org ([18.85.46.34]:58683 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752907Ab0GGBOs (ORCPT ); Tue, 6 Jul 2010 21:14:48 -0400 Date: Tue, 6 Jul 2010 21:14:28 -0400 From: Christoph Hellwig To: Johannes Weiner Cc: Mel Gorman , Minchan Kim , 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 , Christoph Hellwig , KAMEZAWA Hiroyuki , Andrea Arcangeli Subject: Re: [PATCH 12/14] vmscan: Do not writeback pages in direct reclaim Message-ID: <20100707011428.GA3630@infradead.org> References: <20100702125155.69c02f85.akpm@linux-foundation.org> <20100705134949.GC13780@csn.ul.ie> <20100706093529.CCD1.A69D9226@jp.fujitsu.com> <20100706101235.GE13780@csn.ul.ie> <20100706152539.GG13780@csn.ul.ie> <20100706202758.GC18210@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100706202758.GC18210@cmpxchg.org> User-Agent: Mutt/1.5.20 (2009-08-17) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 832 Lines: 16 On Tue, Jul 06, 2010 at 10:27:58PM +0200, Johannes Weiner wrote: > It bypasses the fs. On swapon, the blocks are resolved > (mm/swapfile.c::setup_swap_extents) and then the writeout path uses > bios directly (mm/page_io.c::swap_writepage). > > (GFP_NOFS still includes __GFP_IO, so allows swapping) Exactly. Note that while the stack problems for swap writeout aren't as bad as for filesystems as the whole allocator / extent map footprint is missing it might still be an issue. We still splice the whole block I/O stack footprint over a random stack that might be filled up a lot. -- 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/