From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754160AbdEKDOC (ORCPT ); Wed, 10 May 2017 23:14:02 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:49457 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752398AbdEKDOA (ORCPT ); Wed, 10 May 2017 23:14:00 -0400 Date: Wed, 10 May 2017 20:13:54 -0700 From: "Paul E. McKenney" To: Jens Axboe Cc: peterz@infradead.org, linux-kernel@vger.kernel.org, rostedt@goodmis.org, tglx@linutronix.de Subject: Re: Lockdep splat involving all_q_mutex Reply-To: paulmck@linux.vnet.ibm.com References: <20170510223407.GA7122@linux.vnet.ibm.com> <10e33da8-316d-9f51-b608-91ff7c68e2fa@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <10e33da8-316d-9f51-b608-91ff7c68e2fa@kernel.dk> User-Agent: Mutt/1.5.21 (2010-09-15) X-TM-AS-GCONF: 00 x-cbid: 17051103-0044-0000-0000-00000328CEEA X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007045; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000210; SDB=6.00858944; UDB=6.00425655; IPR=6.00638422; BA=6.00005343; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00015405; XFM=3.00000015; UTC=2017-05-11 03:13:57 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17051103-0045-0000-0000-00000756DA78 Message-Id: <20170511031354.GB3956@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-05-11_02:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1703280000 definitions=main-1705110019 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 10, 2017 at 08:55:54PM -0600, Jens Axboe wrote: > On 05/10/2017 04:34 PM, Paul E. McKenney wrote: > > Hello! > > > > I got the lockdep splat shown below during some rcutorture testing (which > > does CPU hotplug operations) on mainline at commit dc9edaab90de ("Merge > > tag 'acpi-extra-4.12-rc1' of git://git.kernel.org/.../rafael/linux-pm"). > > My kneejerk reaction was just to reverse the "mutex_lock(&all_q_mutex);" > > and "get_online_cpus();" in blk_mq_init_allocated_queue(), but then > > I noticed that commit eabe06595d62 ("block/mq: Cure cpu hotplug lock > > inversion") just got done moving these two statements in the other > > direction. > > The problem is that that patch got merged too early, as it only > fixes a lockdep splat with the cpu hotplug rework. Fix is coming Linus' > way, it's in my for-linus tree. Thank you for the update, looking forward to the fix. Thanx, Paul