Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030463AbWBHS5W (ORCPT ); Wed, 8 Feb 2006 13:57:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030504AbWBHS5W (ORCPT ); Wed, 8 Feb 2006 13:57:22 -0500 Received: from omx2-ext.sgi.com ([192.48.171.19]:41681 "EHLO omx2.sgi.com") by vger.kernel.org with ESMTP id S1030463AbWBHS5W (ORCPT ); Wed, 8 Feb 2006 13:57:22 -0500 Date: Wed, 8 Feb 2006 10:57:14 -0800 From: Paul Jackson To: Christoph Lameter Cc: akpm@osdl.org, ak@suse.de, linux-kernel@vger.kernel.org Subject: Re: Terminate process that fails on a constrained allocation Message-Id: <20060208105714.15bb4bb2.pj@sgi.com> In-Reply-To: References: <20060208103323.7ba3709e.pj@sgi.com> Organization: SGI X-Mailer: Sylpheed version 2.1.7 (GTK+ 2.4.9; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1836 Lines: 49 > No it only disables the oom killer for constrained allocations. But on many big numa systems, the way they are administered, that affectively disables the oom killer. > F.e. a sysadmin may mistakenly start a process allocating too much memory > in a cpuset. The OOM killer will then start randomly shooting other > processes one of which may be a critical process.. Ouch. That same exact claim could be made to justify a patch that removed mm/oom_kill.c entirely. And the same exact claim could be made, dropping the "in a cpuset" phrase, on an UMA desktop PC. The basic premise of the oom killer is that, instead of blowing off the caller, who might innocently have asked for one page too many after some other hog used up all the available memory, we try to pick the worst offender. Get the worst offender, not just who ever finally hit the limit. > Actually a good Denial of service attack than can be used with cpusets > and memory policies. Nothing special about cpusets there. The same DOS opportunity exists on simple one cpu, one node systems. ... Granted, I am objecting to this patch with mixed feelings. I've yet to be convinced that the oom killer is our friend, and half of me (not seriously) is almost wishing it were gone. Would another option be to continue to fine tune the heuristics that the oom killer uses to pick its next victim? What situation did you hit that motivated this change? -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson 1.925.600.0401 - 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/