Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752853Ab1EYS74 (ORCPT ); Wed, 25 May 2011 14:59:56 -0400 Received: from mx1.fusionio.com ([66.114.96.30]:57869 "EHLO mx1.fusionio.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751420Ab1EYS7z (ORCPT ); Wed, 25 May 2011 14:59:55 -0400 X-ASG-Debug-ID: 1306349994-03d6a50f582bf50001-xx1T2L X-Barracuda-Envelope-From: JAxboe@fusionio.com Message-ID: <4DDD51A6.1030509@fusionio.com> Date: Wed, 25 May 2011 20:59:50 +0200 From: Jens Axboe MIME-Version: 1.0 To: Paul Bolle CC: "paulmck@linux.vnet.ibm.com" , Vivek Goyal , linux kernel mailing list Subject: Re: Mysterious CFQ crash and RCU References: <20110519222404.GG12600@redhat.com> <20110521210013.GJ2271@linux.vnet.ibm.com> <20110523152141.GB4019@redhat.com> <20110523153848.GC2310@linux.vnet.ibm.com> <1306189249.15900.10.camel@t41.thuisdomein> <4DDB7D36.60905@fusionio.com> <1306312155.9059.8.camel@t41.thuisdomein> <4DDCC1E4.706@fusionio.com> <1306344530.21978.5.camel@t41.thuisdomein> X-ASG-Orig-Subj: Re: Mysterious CFQ crash and RCU In-Reply-To: <1306344530.21978.5.camel@t41.thuisdomein> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Barracuda-Connect: mail1.int.fusionio.com[10.101.1.21] X-Barracuda-Start-Time: 1306349994 X-Barracuda-URL: http://10.101.1.180:8000/cgi-mod/mark.cgi X-Barracuda-Spam-Score: 0.00 X-Barracuda-Spam-Status: No, SCORE=0.00 using per-user scores of TAG_LEVEL=1000.0 QUARANTINE_LEVEL=1000.0 KILL_LEVEL=9.0 tests= X-Barracuda-Spam-Report: Code version 3.2, rules version 3.2.2.64662 Rule breakdown below pts rule name description ---- ---------------------- -------------------------------------------------- Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 921 Lines: 23 On 2011-05-25 19:28, Paul Bolle wrote: > On Wed, 2011-05-25 at 10:46 +0200, Jens Axboe wrote: >> I don't think we are dealing with bad RCU usage in CFQ. My gut tells me >> that this is related to the merging of cooperating queues. It fits >> roughly with the time frame of when this issue started occuring, and >> some of that reference logic looks fragile/racy. >> >> So if you _can_ test a patch easily, please try this one. It'll disable >> that logic. > > I'm sorry, but with that patch (adapted to out previous discussion, so > simply returning NULL) applied I still hit the same Oops: No worries, it's still a data point. Back to the drawing board... -- Jens Axboe -- 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/