From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 08C476B007B for ; Mon, 15 Feb 2010 03:29:34 -0500 (EST) Received: from m3.gw.fujitsu.co.jp ([10.0.50.73]) by fgwmail7.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id o1F8TVL6021344 for (envelope-from kosaki.motohiro@jp.fujitsu.com); Mon, 15 Feb 2010 17:29:32 +0900 Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 7F8C845DE53 for ; Mon, 15 Feb 2010 17:29:31 +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 4425A45DE4D for ; Mon, 15 Feb 2010 17:29:31 +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 071041DB803C for ; Mon, 15 Feb 2010 17:29:31 +0900 (JST) Received: from m107.s.css.fujitsu.com (m107.s.css.fujitsu.com [10.249.87.107]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id B46531DB803F for ; Mon, 15 Feb 2010 17:29:30 +0900 (JST) From: KOSAKI Motohiro Subject: Re: [patch 6/7 -mm] oom: avoid oom killer for lowmem allocations In-Reply-To: References: Message-Id: <20100215172530.72A1.A69D9226@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Date: Mon, 15 Feb 2010 17:29:29 +0900 (JST) Sender: owner-linux-mm@kvack.org To: David Rientjes Cc: kosaki.motohiro@jp.fujitsu.com, Andrew Morton , Rik van Riel , KAMEZAWA Hiroyuki , Nick Piggin , Andrea Arcangeli , Balbir Singh , Lubos Lunak , linux-kernel@vger.kernel.org, linux-mm@kvack.org List-ID: > If memory has been depleted in lowmem zones even with the protection > afforded to it by /proc/sys/vm/lowmem_reserve_ratio, it is unlikely that > killing current users will help. The memory is either reclaimable (or > migratable) already, in which case we should not invoke the oom killer at > all, or it is pinned by an application for I/O. Killing such an > application may leave the hardware in an unspecified state and there is > no guarantee that it will be able to make a timely exit. > > Lowmem allocations are now failed in oom conditions so that the task can > perhaps recover or try again later. Killing current is an unnecessary > result for simply making a GFP_DMA or GFP_DMA32 page allocation and no > lowmem allocations use the now-deprecated __GFP_NOFAIL bit so retrying is > unnecessary. > > Previously, the heuristic provided some protection for those tasks with > CAP_SYS_RAWIO, but this is no longer necessary since we will not be > killing tasks for the purposes of ISA allocations. The main difference of Kamezawasan's patch is, his patch treated DMA zone is filled by mlocked page too. but I personally think such case should be solved auto page migration mechanism. (probably, mel's memory compaction patch provide its base infrastructure). So this patch seems enough and proper. Reviewed-by: KOSAKI Motohiro > > Signed-off-by: David Rientjes > --- > mm/page_alloc.c | 3 +++ > 1 files changed, 3 insertions(+), 0 deletions(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -1914,6 +1914,9 @@ rebalance: > * running out of options and have to consider going OOM > */ > if (!did_some_progress) { > + /* The oom killer won't necessarily free lowmem */ > + if (high_zoneidx < ZONE_NORMAL) > + goto nopage; > if ((gfp_mask & __GFP_FS) && !(gfp_mask & __GFP_NORETRY)) { > if (oom_killer_disabled) > goto nopage; > > -- > 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 -- 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