Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756654Ab1DZG3T (ORCPT ); Tue, 26 Apr 2011 02:29:19 -0400 Received: from mail-ww0-f44.google.com ([74.125.82.44]:62289 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756108Ab1DZG3S convert rfc822-to-8bit (ORCPT ); Tue, 26 Apr 2011 02:29:18 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=PWLd4E5jmr1De7yo9Jq13BNuXJ70lfoCFaQpscJlyoglpHxjrtgf5qWP2oYjZevvhK FAQH+ziq5nnLEmKq0gCySUNPISHxP0ZBOUE+AHyGpKdZuvhhYoS6wMSoVr/79pxkJp9B xIPL08B2RAWYV6eARAb8GpMvy6GHZgU7fLmA4= 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 To: Wu Fengguang Cc: linux-mm , Linux Kernel Mailing List Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1661 Lines: 40 On Tue, Apr 26, 2011 at 2:25 PM, Wu Fengguang wrote: > 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。If 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 allocation >> >> 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? -- Regards dave -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/