From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with ESMTP id 18738900001 for ; Tue, 26 Apr 2011 02:29:20 -0400 (EDT) Received: by wwi36 with SMTP id 36so243197wwi.26 for ; Mon, 25 Apr 2011 23:29:17 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20110426062535.GB19717@localhost> References: <20110426055521.GA18473@localhost> <20110426062535.GB19717@localhost> Date: Tue, 26 Apr 2011 14:29:15 +0800 Message-ID: Subject: Re: readahead and oom From: Dave Young Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Wu Fengguang Cc: linux-mm , Linux Kernel Mailing List On Tue, Apr 26, 2011 at 2:25 PM, Wu Fengguang wrot= e: > On Tue, Apr 26, 2011 at 02:07:17PM +0800, Dave Young wrote: >> On Tue, Apr 26, 2011 at 2:05 PM, Dave Young = wrote: >> > On Tue, Apr 26, 2011 at 1:55 PM, Wu Fengguang = wrote: >> >> On Tue, Apr 26, 2011 at 01:49:25PM +0800, Dave Young wrote: >> >>> Hi, >> >>> >> >>> When memory pressure is high, readahead could cause oom killing. >> >>> IMHO we should stop readaheading under such circumstances=E3=80=82If= it's true >> >>> how to fix it? >> >> >> >> Good question. Before OOM there will be readahead thrashings, which >> >> can be addressed by this patch: >> >> >> >> http://lkml.org/lkml/2010/2/2/229 >> > >> > Hi, I'm not clear about the patch, could be regard as below cases? >> > 1) readahead alloc fail due to low memory such as other large allocati= on >> >> For example vm balloon allocate lots of memory, then readahead could >> fail immediately and then oom > > If true, that would be the problem of vm balloon. It's not good to > consume lots of memory all of a sudden, which will likely impact lots > of kernel subsystems. > > btw readahead page allocations are completely optional. They are OK to > fail and in theory shall not trigger OOM on themselves. We may > consider passing __GFP_NORETRY for readahead page allocations. Good idea, care to submit a patch? --=20 Regards dave -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org