Messages in this thread | | | Date | Mon, 7 Mar 2011 08:54:15 +0800 | Subject | Re: [PATCH 05/10] block: remove per-queue plugging | From | Shaohua Li <> |
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2011/3/5 Jens Axboe <jaxboe@fusionio.com>: > On 2011-03-04 22:43, Mike Snitzer wrote: >> On Fri, Mar 04 2011 at 8:02am -0500, >> Shaohua Li <shli@kernel.org> wrote: >> >>> 2011/3/4 Mike Snitzer <snitzer@redhat.com>: >>>> I'm now hitting a lockdep issue, while running a 'for-2.6.39/stack-plug' >>>> kernel, when I try an fsync heavy workload to a request-based mpath >>>> device (the kernel ultimately goes down in flames, I've yet to look at >>>> the crashdump I took) >>>> >>>> >>>> ======================================================= >>>> [ INFO: possible circular locking dependency detected ] >>>> 2.6.38-rc6-snitm+ #2 >>>> ------------------------------------------------------- >>>> ffsb/3110 is trying to acquire lock: >>>> (&(&q->__queue_lock)->rlock){..-...}, at: [<ffffffff811b4c4d>] flush_plug_list+0xbc/0x135 >>>> >>>> but task is already holding lock: >>>> (&rq->lock){-.-.-.}, at: [<ffffffff8137132f>] schedule+0x16a/0x725 >>>> >>>> which lock already depends on the new lock. >>> I hit this too. Can you check if attached debug patch fixes it? >> >> Fixes it for me. > > The preempt bit in block/ should not be needed. Can you check whether > it's the moving of the flush in sched.c that does the trick? yes, it's not related to the lockdep issue. but I think we still need it. if there is a preempt between attempt_plub_merge(), we do queue flush, then we might hit an incomplete list of request->biotail. Am I missing anything?
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