From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH 12/14] vmscan: Do not writeback pages in direct reclaim Date: Tue, 6 Jul 2010 21:14:28 -0400 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 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 To: Johannes Weiner Return-path: Content-Disposition: inline In-Reply-To: <20100706202758.GC18210@cmpxchg.org> Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org 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, 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