Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754709Ab1DTNbz (ORCPT ); Wed, 20 Apr 2011 09:31:55 -0400 Received: from mx2.fusionio.com ([64.244.102.31]:53630 "EHLO mx2.fusionio.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752223Ab1DTNbx (ORCPT ); Wed, 20 Apr 2011 09:31:53 -0400 X-ASG-Debug-ID: 1303306312-01de284cf816e490001-xx1T2L X-Barracuda-Envelope-From: JAxboe@fusionio.com Message-ID: <4DAEE049.7050407@fusionio.com> Date: Wed, 20 Apr 2011 15:31:53 +0200 From: Jens Axboe MIME-Version: 1.0 To: Michal Hocko CC: Linus Torvalds , LKML Subject: Re: 2.6.39-rc4 BUG: unable to handle kernel NULL pointer dereference at 0000000c IP: cfq_insert_request+0x1d/0x3f5 References: <20110420125824.GA3507@tiehlicka.suse.cz> <4DAEDBEB.7060904@fusionio.com> <20110420132903.GA13554@tiehlicka.suse.cz> X-ASG-Orig-Subj: Re: 2.6.39-rc4 BUG: unable to handle kernel NULL pointer dereference at 0000000c IP: cfq_insert_request+0x1d/0x3f5 In-Reply-To: <20110420132903.GA13554@tiehlicka.suse.cz> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Barracuda-Connect: mail1.int.fusionio.com[10.101.1.21] X-Barracuda-Start-Time: 1303306312 X-Barracuda-URL: http://10.101.1.181:8000/cgi-mod/mark.cgi X-Barracuda-Spam-Score: 0.20 X-Barracuda-Spam-Status: No, SCORE=0.20 using global scores of TAG_LEVEL=1000.0 QUARANTINE_LEVEL=1000.0 KILL_LEVEL=9.0 tests=PR0N_SUBJECT X-Barracuda-Spam-Report: Code version 3.2, rules version 3.2.2.61410 Rule breakdown below pts rule name description ---- ---------------------- -------------------------------------------------- 0.20 PR0N_SUBJECT Subject has letters around special characters (pr0n) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2279 Lines: 58 On 2011-04-20 15:29, Michal Hocko wrote: > On Wed 20-04-11 15:13:15, Jens Axboe wrote: >> On 2011-04-20 14:58, Michal Hocko wrote: >>> Hi, >>> I am not able to boot with the current git tree >>> (2.6.39-rc4-00089-g2f666bc). 2.6.39-rc3 boots just fine. >>> >>> The backtrace [1] looks really messy. >>> >>> I have seen a similar backtrace at https://lkml.org/lkml/2011/3/25/169 >>> and tried the patch from https://lkml.org/lkml/2011/3/25/173 but it >>> didn't help. The backtrace looks similar (much smaller) but the machine >>> ends up dead as well with unbalanced preempt counter[2]. >>> >>> The config is attached. >>> >>> Is this a known problem? >>> >>> --- >>> * [1] backtrace with the current git tree (2f666bc) >>> >>> [ 31.207283] BUG: unable to handle kernel NULL pointer dereference at 0000000c >>> NULL pointer dereference[ 31.207540] IP: at 0000000c >>> [ 31.207540] IP: [] cfq_insert_request+0x1d/0x3f5 >>> [ 31.207720] *pde = 00000000 [] cfq_insert_request+0x1d/0x3f5 >>> NULL pointer dereference[ 31.207720] *pde = 00000000 >>> at 0000000c >>> [ 31.207888] Oops: 0000 [#1] >>> PREEMPT [ 31.207540] IP:[ 31.207888] Oops: 0000 [#1] SMP PREEMPT DEBUG_PAGEALLOC [] cfq_insert_request+0x1d/0x3f5 >>> SMP DEBUG_PAGEALLOC[ 31.207720] *pde = 00000000 >>> [ 31.207888] Oops: 0000 [#1] PREEMPT [ 31.208186] last sysfs file: /sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/queue/scheduler >> >> Ahh hang on, this may be a good clue. Does your boot scripts change the >> IO scheduler? > > Good one... > Yes, I have: > echo deadline > /sys/block/sda/queue/scheduler > in /etc/rc.local > > I am able to boot after I remove it. This is the first time I have seen > "last sysfs file" being useful. Haha, good point, it's the first time for me as well IO think. > Still want me to test the patch from the other email? No, that wont help you. I do wonder why this is a rc3 vs rc4 change. I'll dig around and send you something to try. -- 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/