Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752127AbdLFMZW (ORCPT ); Wed, 6 Dec 2017 07:25:22 -0500 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:33824 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751748AbdLFMZT (ORCPT ); Wed, 6 Dec 2017 07:25:19 -0500 Subject: Re: 4.14: WARNING: CPU: 4 PID: 2895 at block/blk-mq.c:1144 with virtio-blk (also 4.12 stable) To: Christoph Hellwig Cc: Jens Axboe , Bart Van Assche , "linux-block@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Thomas Gleixner , Stefan Haberland , linux-s390 , Martin Schwidefsky References: <20171123143453.GA29715@lst.de> <20171123182542.GA2680@lst.de> <899f1638-cca4-28e6-3225-51505a053d45@de.ibm.com> <20171123183232.GA2845@lst.de> <92ef1aae-90b5-f14f-390e-bfab97899431@de.ibm.com> <419d8565-9cbe-16ac-3d5d-5945098694bc@de.ibm.com> <20171127155409.GA6937@lst.de> <20171204162108.GA12482@lst.de> From: Christian Borntraeger Date: Wed, 6 Dec 2017 13:25:11 +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: <20171204162108.GA12482@lst.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 17120612-0040-0000-0000-000003F6EB04 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17120612-0041-0000-0000-000025F9E345 Message-Id: <5ab91c56-b117-f4fa-3049-a4f8a5493155@de.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-12-06_05:,, 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=1011 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1712060181 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1469 Lines: 38 On 12/04/2017 05:21 PM, Christoph Hellwig wrote: > On Wed, Nov 29, 2017 at 08:18:09PM +0100, Christian Borntraeger wrote: >> Works fine under KVM with virtio-blk, but still hangs during boot in an LPAR. >> FWIW, the system not only has scsi disks via fcp but also DASDs as a boot disk. >> Seems that this is the place where the system stops. (see the sysrq-t output >> at the bottom). > > Can you check which of the patches in the tree is the culprit? >From this branch git://git.infradead.org/users/hch/block.git blk-mq-hotplug-fix commit 11b2025c3326f7096ceb588c3117c7883850c068 -> bad blk-mq: create a blk_mq_ctx for each possible CPU does not boot on DASD and commit 9c6ae239e01ae9a9f8657f05c55c4372e9fc8bcc -> good genirq/affinity: assign vectors to all possible CPUs does boot with DASD disks. Also adding Stefan Haberland if he has an idea why this fails on DASD and adding Martin (for the s390 irq handling code). Some history: I got this warning "WARNING: CPU: 4 PID: 2895 at block/blk-mq.c:1144 with virtio-blk (also 4.12 stable)" since 4.13 (and also in 4.12 stable) on CPU hotplug of previously unavailable CPUs (real hotplug, no offline/online) This was introduced with blk-mq: Create hctx for each present CPU commit 4b855ad37194f7bdbb200ce7a1c7051fecb56a08 And Christoph is currently working on a fix. The fixed kernel does boot with virtio-blk and it fixes the warning but it hangs (outstanding I/O) with dasd disks.