From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751394AbdKUSMu (ORCPT ); Tue, 21 Nov 2017 13:12:50 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:49308 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751345AbdKUSMs (ORCPT ); Tue, 21 Nov 2017 13:12:48 -0500 Subject: Re: 4.14: WARNING: CPU: 4 PID: 2895 at block/blk-mq.c:1144 with virtio-blk (also 4.12 stable) To: Jens Axboe , Bart Van Assche , "virtualization@lists.linux-foundation.org" , "linux-block@vger.kernel.org" , "mst@redhat.com" , "jasowang@redhat.com" , "linux-kernel@vger.kernel.org" , Christoph Hellwig References: <9c5eec5d-f542-4d76-6933-6fe31203ce09@de.ibm.com> <1511205644.2396.32.camel@wdc.com> <04526c98-ffc5-1eca-3aa8-50f9212c4323@de.ibm.com> <5c9f2228-0a8b-8225-7038-e6cb3f31ca0b@kernel.dk> <2e44dbd3-2f90-c267-560c-91d1d4b0e892@de.ibm.com> <823b9dd5-7781-5a72-03ff-bc931433fc19@kernel.dk> <15f232d2-2aaa-df7c-57e8-2f710e051e84@de.ibm.com> <055f040d-3f9a-a8fd-e8e2-326c6b9094a1@kernel.dk> From: Christian Borntraeger Date: Tue, 21 Nov 2017 19:12:39 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: <055f040d-3f9a-a8fd-e8e2-326c6b9094a1@kernel.dk> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 17112118-0012-0000-0000-0000059008FE X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17112118-0013-0000-0000-0000190ADA11 Message-Id: <1aeecf2e-a68e-4c18-5912-2473f457e6ea@de.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-11-21_06:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1711210239 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/21/2017 07:09 PM, Jens Axboe wrote: > On 11/21/2017 10:27 AM, Jens Axboe wrote: >> On 11/21/2017 03:14 AM, Christian Borntraeger wrote: >>> Bisect points to >>> >>> 1b5a7455d345b223d3a4658a9e5fce985b7998c1 is the first bad commit >>> commit 1b5a7455d345b223d3a4658a9e5fce985b7998c1 >>> Author: Christoph Hellwig >>> Date: Mon Jun 26 12:20:57 2017 +0200 >>> >>> blk-mq: Create hctx for each present CPU >>> >>> commit 4b855ad37194f7bdbb200ce7a1c7051fecb56a08 upstream. >>> >>> Currently we only create hctx for online CPUs, which can lead to a lot >>> of churn due to frequent soft offline / online operations. Instead >>> allocate one for each present CPU to avoid this and dramatically simplify >>> the code. >>> >>> Signed-off-by: Christoph Hellwig >>> Reviewed-by: Jens Axboe >>> Cc: Keith Busch >>> Cc: linux-block@vger.kernel.org >>> Cc: linux-nvme@lists.infradead.org >>> Link: http://lkml.kernel.org/r/20170626102058.10200-3-hch@lst.de >>> Signed-off-by: Thomas Gleixner >>> Cc: Oleksandr Natalenko >>> Cc: Mike Galbraith >>> Signed-off-by: Greg Kroah-Hartman >> >> I wonder if we're simply not getting the masks updated correctly. I'll >> take a look. > > Can't make it trigger here. We do init for each present CPU, which means > that if I offline a few CPUs here and register a queue, those still show > up as present (just offline) and get mapped accordingly. > > From the looks of it, your setup is different. If the CPU doesn't show > up as present and it gets hotplugged, then I can see how this condition > would trigger. What environment are you running this in? We might have > to re-introduce the cpu hotplug notifier, right now we just monitor > for a dead cpu and handle that. I am not doing a hot unplug and the replug, I use KVM and add a previously not available CPU. in libvirt/virsh speak: 4