From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from esa4.hgst.iphmx.com ([216.71.154.42]:64238 "EHLO esa4.hgst.iphmx.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751000AbdE3SLt (ORCPT ); Tue, 30 May 2017 14:11:49 -0400 From: Bart Van Assche To: "keith.busch@intel.com" , "krisman@collabora.co.uk" CC: "linux-nvme@lists.infradead.org" , "linux-block@vger.kernel.org" , "axboe@fb.com" Subject: Re: WARNING triggers at blk_mq_update_nr_hw_queues during nvme_reset_work Date: Tue, 30 May 2017 18:09:22 +0000 Message-ID: <1496167761.2627.22.camel@sandisk.com> References: <8760giqnyb.fsf@dilma.collabora.co.uk> <20170530175549.GC2845@localhost.localdomain> In-Reply-To: <20170530175549.GC2845@localhost.localdomain> Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org List-Id: linux-block@vger.kernel.org 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 a= n > > 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: > >=20 > > https://intel-gfx-ci.01.org/CI/CI_DRM_2672/fi-kbl-7500u/igt@kms_pipe_cr= c_basic@suspend-read-crc-pipe-a.html > >=20 > > Please notice that the test we do in the CI involves putting the > > machine to sleep (PM), and the issue triggers when resuming execution. > >=20 > > 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. > >=20 > > Any help is appreciated :) >=20 > Hi Gabriel, >=20 > 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. >=20 > I think the below should fix it (CC'ing block list and developers). >=20 > --- > 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; > } > =20 > -void blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, int nr_hw_qu= eues) > +static void __blk_mq_update_nr_hw_queues(struct blk_mq_tag_set *set, > + int nr_hw_queues) > { > struct request_queue *q; > =20 > @@ -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_qu= eues) > +{ > + 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