From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id D79E36B004D for ; Wed, 15 Jul 2009 23:10:49 -0400 (EDT) Message-ID: <4A5E9A33.3030704@redhat.com> Date: Wed, 15 Jul 2009 23:10:43 -0400 From: Rik van Riel MIME-Version: 1.0 Subject: Re: [PATCH -mm] throttle direct reclaim when too many pages are isolated already References: <20090715223854.7548740a@bree.surriel.com> <20090715194820.237a4d77.akpm@linux-foundation.org> In-Reply-To: <20090715194820.237a4d77.akpm@linux-foundation.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Andrew Morton Cc: KOSAKI Motohiro , LKML , linux-mm , Wu Fengguang List-ID: Andrew Morton wrote: > On Wed, 15 Jul 2009 22:38:53 -0400 Rik van Riel wrote: > >> When way too many processes go into direct reclaim, it is possible >> for all of the pages to be taken off the LRU. One result of this >> is that the next process in the page reclaim code thinks there are >> no reclaimable pages left and triggers an out of memory kill. >> >> One solution to this problem is to never let so many processes into >> the page reclaim path that the entire LRU is emptied. Limiting the >> system to only having half of each inactive list isolated for >> reclaim should be safe. >> > > Since when? Linux page reclaim has a bilion machine years testing and > now stuff like this turns up. Did we break it or is this a > never-before-discovered workload? It's been there for years, in various forms. It hardly ever shows up, but Kosaki's patch series give us a nice chance to fix it for good. >> @@ -1049,6 +1070,10 @@ static unsigned long shrink_inactive_lis >> struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc); >> int lumpy_reclaim = 0; >> >> + while (unlikely(too_many_isolated(zone, file))) { >> + schedule_timeout_interruptible(HZ/10); >> + } > > This (incorrectly-laid-out) code is a no-op if signal_pending(). Good point, I should add some code to break out of page reclaim if a fatal signal is pending, and use a normal schedule_timeout otherwise. Btw, how is this laid out wrong? How do I do this better? -- All rights reversed. -- 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