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Date: Thu, 8 May 2014 21:27:42 -0600 From: Jens Axboe <axboe@...com> To: Sasha Levin <sasha.levin@...cle.com> CC: LKML <linux-kernel@...r.kernel.org>, Dave Jones <davej@...hat.com> Subject: Re: blk-mq: WARN at block/blk-mq.c:585 __blk_mq_run_hw_queue 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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