From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S964792AbaEGPz1 (ORCPT ); Wed, 7 May 2014 11:55:27 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:38637 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934072AbaEGPzV (ORCPT ); Wed, 7 May 2014 11:55:21 -0400 Message-ID: <536A5764.4020606@fb.com> Date: Wed, 7 May 2014 09:55:16 -0600 From: Jens Axboe User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 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> In-Reply-To: <536A56E4.5020909@oracle.com> Content-Type: text/plain; charset="ISO-8859-1" 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=2014-05-07_05:2014-05-07,2014-05-07,1970-01-01 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 kscore.is_bulkscore=2.77374085755344e-07 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-1405070185 X-FB-Internal: deliver Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.