From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with SMTP id D7E1D6B003D for ; Tue, 10 Feb 2009 00:56:43 -0500 (EST) From: Nick Piggin Subject: Re: [PATCH] mm fix page writeback accounting to fix oom condition under heavy I/O Date: Tue, 10 Feb 2009 16:56:13 +1100 References: <20090120122855.GF30821@kernel.dk> <20090210033652.GA28435@Krystal> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200902101656.13792.nickpiggin@yahoo.com.au> Sender: owner-linux-mm@kvack.org To: Linus Torvalds Cc: Mathieu Desnoyers , KOSAKI Motohiro , Jens Axboe , akpm@linux-foundation.org, Peter Zijlstra , Ingo Molnar , thomas.pi@arcor.dea, Yuriy Lalym , ltt-dev@lists.casi.polymtl.ca, linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: On Tuesday 10 February 2009 16:23:56 Linus Torvalds wrote: > On Mon, 9 Feb 2009, Mathieu Desnoyers wrote: > > So this patch fixes this behavior by only decrementing the page > > accounting _after_ the block I/O writepage has been done. > > This makes no sense, really. > > Or rather, I don't mind the notion of updating the counters only after IO > per se, and _that_ part of it probably makes sense. But why is it that you > only then fix up two of the call-sites. There's a lot more call-sites than > that for this function. Well if you do that, then I'd think you also have to change some calculations that today use dirty+writeback. In some ways it does make sense, but OTOH it is natural in the pagecache since it was introduced to treat writeback as basically equivalent to dirty. So writeback && !dirty pages shouldn't cause things to blow up, or if it does then hopefully it is a simple bug somewhere. -- 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