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 E95786B0096 for ; Fri, 8 Jan 2010 04:32:59 -0500 (EST) Received: from m3.gw.fujitsu.co.jp ([10.0.50.73]) by fgwmail5.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o089WvNM012945 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Fri, 8 Jan 2010 18:32:57 +0900 Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 18E3C45DE51 for ; Fri, 8 Jan 2010 18:32:57 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id ED53745DE50 for ; Fri, 8 Jan 2010 18:32:56 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id D544C1DB803E for ; Fri, 8 Jan 2010 18:32:56 +0900 (JST) Received: from m108.s.css.fujitsu.com (m108.s.css.fujitsu.com [10.249.87.108]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 7452EE08004 for ; Fri, 8 Jan 2010 18:32:53 +0900 (JST) From: KOSAKI Motohiro Subject: Re: Commit f50de2d38 seems to be breaking my oom killer In-Reply-To: <20100108092503.GA3985@csn.ul.ie> References: <20100108130742.C138.A69D9226@jp.fujitsu.com> <20100108092503.GA3985@csn.ul.ie> Message-Id: <20100108183156.C144.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Fri, 8 Jan 2010 18:32:52 +0900 (JST) Sender: owner-linux-mm@kvack.org To: Mel Gorman Cc: kosaki.motohiro@jp.fujitsu.com, Minchan Kim , Will Newton , linux-mm@kvack.org, Rik van Riel , Andrew Morton List-ID: > > Umm.. > > This code looks a bit risky. Please imazine asymmetric numa. If the system has > > very small node, its nude have unreclaimable state at almost time. > > > > Thus, if all zones in the node are unreclaimable, It should be slept. To retry balance_pgdat() > > is meaningless. this is original intention, I think. > > > > So why can't we write following? > > > > From c00d7bb29552d3aa4d934b5007f3d52ade5f2dfd Mon Sep 17 00:00:00 2001 > > From: KOSAKI Motohiro > > Date: Fri, 8 Jan 2010 08:36:05 +0900 > > Subject: [PATCH] vmscan: kswapd don't retry balance_pgdat() if all zones are unreclaimable > > > > Commit f50de2d3 (vmscan: have kswapd sleep for a short interval and > > double check it should be asleep) can cause kswapd to enter an infinite > > loop if running on a single-CPU system. If all zones are unreclaimble, > > sleeping_prematurely return 1 and kswapd will call balance_pgdat() > > again. but it's totally meaningless, balance_pgdat() doesn't anything > > against unreclaimable zone! > > > > Sure, that would be a safer check in the face of very small NUMA nodes. > It could do with a comment explaining why unreclaimable zones are being skipped > but it's no biggie. Will, can you confirm this patch also fixes your problem. > > Kosaki, if Will reports success, can you then report that patch please > for upstreaming? After today, I'm offline for a week so it'd be at > least 10 days before I'd do it. Thanks Sure. thanks. -- 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