On 05/09/2014 06:12 AM, Shaohua Li wrote: > On Thu, May 08, 2014 at 09:27:42PM -0600, Jens Axboe wrote: >> 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. > > Does reverting 1eaade629f5c47 change anything? > > The ctx->online isn't changed immediately when cpu is offline, likely there > are > something wrong. I'm wondering why we need that patch?
We don't strictly need it. That commit isn't in what Sasha tested, however. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
