From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756066AbaEIDWW (ORCPT ); Thu, 8 May 2014 23:22:22 -0400 Received: from aserp1040.oracle.com ([141.146.126.69]:41832 "EHLO aserp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755830AbaEIDWV (ORCPT ); Thu, 8 May 2014 23:22:21 -0400 Message-ID: <536C49E6.9000503@oracle.com> Date: Thu, 08 May 2014 23:22:14 -0400 From: Sasha Levin User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.4.0 MIME-Version: 1.0 To: Jens Axboe 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> In-Reply-To: <536A5764.4020606@fb.com> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Source-IP: acsinet22.oracle.com [141.146.126.238] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? Thanks, Sasha