On Tue, 2017-05-30 at 13:55 -0400, Keith Busch wrote: > On Tue, May 30, 2017 at 02:00:44PM -0300, Gabriel Krisman Bertazi wrote: > > Since the merge window for 4.12, one of the machines in Intel's CI > > started to hit the WARN_ON below at blk_mq_update_nr_hw_queues during an > > nvme_reset_work. The issue persists with the latest 4.12-rc3, and full > > dmesg from boot, up to the moment where the WARN_ON triggers is > > available at the following link: > > > > https://intel-gfx-ci.01.org/CI/CI_DRM_2672/fi-kbl-7500u/igt@kms_pipe_crc_basic@xxxxxxxxxxxxxxxxxxxxxxxxxxxx > > > > Please notice that the test we do in the CI involves putting the > > machine to sleep (PM), and the issue triggers when resuming execution. > > > > I have not been able to get my hands on the machine yet to do an actual > > bisect, but I'm wondering if you guys might have an idea of what is > > wrong. > > > > Any help is appreciated :) > > Hi Gabriel, > > This appears to be new behavior in blk-mq's tag set update with commit > 705cda97e. This is asserting a lock is held, but none of the drivers > that call the export are take that lock. > > I think the below should fix it (CC'ing block list and developers). > > --- > diff --git a/block/blk-mq.c b/block/blk-mq.c > index f2224ffd..1bccced 100644 > --- a/block/blk-mq.c > +++ b/block/blk-mq.c > @@ -2641,7 +2641,8 @@ int blk_mq_update_nr_requests(struct request_queue *q, unsigned int nr) > return ret; > } > > -void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues) > +static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, > + int nr_hw_queues) > { > struct request_queue *q; > > @@ -2665,6 +2666,13 @@ void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues) > list_for_each_entry(q, &set->tag_list, tag_set_list) > blk_mq_unfreeze_queue(q); > } > + > +void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_queues) > +{ > + mutex_lock(&set->tag_list_lock); > + __blk_mq_update_nr_hw_queues(set, nr_hw_queues); > + mutex_unlock(&set->tag_list_lock); > +} > EXPORT_SYMBOL_GPL(blk_mq_update_nr_hw_queues); These changes look fine to me, hence: Reviewed-by: Bart Van Assche <Bart.VanAssche@xxxxxxxxxxx>
