From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755687AbaEID1t (ORCPT ); Thu, 8 May 2014 23:27:49 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:17746 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752051AbaEID1s (ORCPT ); Thu, 8 May 2014 23:27:48 -0400 Message-ID: <536C4B2E.4030906@fb.com> Date: Thu, 8 May 2014 21:27:42 -0600 From: Jens Axboe User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Sasha Levin CC: LKML , Dave Jones Subject: Re: blk-mq: WARN at block/blk-mq.c:585 __blk_mq_run_hw_queue References: <536A532C.4050001@oracle.com> <536A5532.1060008@fb.com> <536A56E4.5020909@oracle.com> <536A5764.4020606@fb.com> <536C49E6.9000503@oracle.com> In-Reply-To: <536C49E6.9000503@oracle.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.57.29] X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.11.96,1.0.14,0.0.0000 definitions=2014-05-09_01:2014-05-08,2014-05-09,1970-01-01 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 kscore.is_bulkscore=4.05817854737256e-06 kscore.compositescore=0 circleOfTrustscore=126.169791002841 compositescore=0.9989857498195 urlsuspect_oldscore=0.9989857498195 suspectscore=0 recipient_domain_to_sender_totalscore=0 phishscore=0 bulkscore=0 kscore.is_spamscore=0 recipient_to_sender_totalscore=0 recipient_domain_to_sender_domain_totalscore=62764 rbsscore=0.9989857498195 spamscore=0 recipient_to_sender_domain_totalscore=0 urlsuspectscore=0.9 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=7.0.1-1402240000 definitions=main-1405090048 X-FB-Internal: deliver Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2014-05-08 21:22, Sasha Levin wrote: > On 05/07/2014 11:55 AM, Jens Axboe wrote: >> On 05/07/2014 09:53 AM, Sasha Levin wrote: >>> On 05/07/2014 11:45 AM, Jens Axboe wrote: >>>> On 05/07/2014 09:37 AM, Sasha Levin wrote: >>>>> Hi all, >>>>> >>>>> While fuzzing with trinity inside a KVM tools guest running the latest -next >>>>> kernel I've stumbled on the following spew: >>>>> >>>>> [ 986.962569] WARNING: CPU: 41 PID: 41607 at block/blk-mq.c:585 __blk_mq_run_hw_queue+0x90/0x500() >>>> >>>> I'm going to need more info than this. What were you running? How as kvm >>>> invoked (nr cpus)? >>> >>> Sure! >>> >>> It's running in a KVM tools guest (not qemu), with the following options: >>> >>> '--rng --balloon -m 28000 -c 48 -p "numa=fake=32 init=/virt/init zcache ftrace_dump_on_oops debugpat kvm.mmu_audit=1 slub_debug=FZPU rcutorture.rcutorture_runnable=0 loop.max_loop=64 zram.num_devices=4 rcutorture.nreaders=8 oops=panic nr_hugepages=1000 numa_balancing=enable'. >>> >>> So basically 48 vcpus (the host has 128 physical ones), and ~28G of RAM. >>> >>> I've been running trinity as a fuzzer, which doesn't handle logging too well, >>> so I can't reproduce it's actions easily. >>> >>> There was an additional stress of hotplugging CPUs and memory during this recent >>> fuzzing run, so it's fair to suspect that this happened as a result of that. >> >> Aha! >> >>> Anything else that might be helpful? >> >> No, not too surprising given the info that cpu hotplug was being >> stressed at the same time. blk-mq doesn't quiesce when this happens, so >> it's very unlikely that there are races between updating the cpu masks >> and flushing out the previously queued work. > > So this warning is something you'd expect when CPUs go up/down? Let me put it this way - I'm not surprised that it triggered, but it will of course be fixed up. -- Jens Axboe