Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755401AbXLDQEr (ORCPT ); Tue, 4 Dec 2007 11:04:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753582AbXLDQEh (ORCPT ); Tue, 4 Dec 2007 11:04:37 -0500 Received: from perninha.conectiva.com.br ([200.140.247.100]:55203 "EHLO perninha.conectiva.com.br" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753512AbXLDQEg (ORCPT ); Tue, 4 Dec 2007 11:04:36 -0500 Date: Tue, 4 Dec 2007 14:04:25 -0200 From: "Luiz Fernando N. Capitulino" To: Ingo Molnar Cc: Linus Torvalds , Linux Kernel Mailing List , herton@mandriva.com.br, dvgevers@xs4all.nl Subject: Re: [local DoS] Re: Linux 2.6.24-rc4 Message-ID: <20071204140425.05b0b458@mandriva.com.br> In-Reply-To: <20071204160005.GA29783@elte.hu> References: <20071204120715.4ea204a8@mandriva.com.br> <20071204160005.GA29783@elte.hu> Organization: Mandriva X-Mailer: Claws Mail 3.1.0 (GTK+ 2.12.2; i586-mandriva-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1353 Lines: 39 Em Tue, 4 Dec 2007 17:00:05 +0100 Ingo Molnar escreveu: | | * Linus Torvalds wrote: | | > | > | > On Tue, 4 Dec 2007, Luiz Fernando N. Capitulino wrote: | > > | > > sched_rr_get_interval(1, NULL); | > | > Looks like we have a zero "cfs_rq->load.weight". | > | > Ingo? Both sched_slice() and __sched_slice() do a divide by the | > runqueue weight, and at least dequeue_task_fair() explicitly checks | > for that being zero, so clearly zero is a possible value. Hmm? | | yeah, i can reproduce this crash too. | | The problem is on SMP: if sched_rr_get_interval() gets a task from an | otherwise idle runqueue, then rq->load.weight is 0. Normally | sched_slice() is only used on a busy runqueue. So the correct fixup site | is not in sched_slice() but in sys_sched_rr_get_interval() - i'm working | on the right fix, i hope to be able to send a pull request in a few | minutes. Ingo, I can reproduce this w/o SMP support as well. (Also, the backtrace I sent was reproduced on a UP machine with a SMP kernel). -- Luiz Fernando N. Capitulino -- 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/