From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 13 Apr 2017 14:23:58 +0200 From: Benjamin Block To: Bart Van Assche Cc: "linux-scsi@vger.kernel.org" , "linux-block@vger.kernel.org" , "axboe@kernel.dk" Subject: Re: [PATCH v4 0/6] Avoid that scsi-mq and dm-mq queue processing stalls sporadically References: <20170407181654.27836-1-bart.vanassche@sandisk.com> <20170412105538.GB22576@bblock-ThinkPad-W530> <1492020683.2764.9.camel@sandisk.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 In-Reply-To: <1492020683.2764.9.camel@sandisk.com> Message-Id: <20170413122358.GH22576@bblock-ThinkPad-W530> List-ID: On Wed, Apr 12, 2017 at 06:11:25PM +0000, Bart Van Assche wrote: > On Wed, 2017-04-12 at 12:55 +0200, Benjamin Block wrote: > > On Fri, Apr 07, 2017 at 11:16:48AM -0700, Bart Van Assche wrote: > > > The six patches in this patch series fix the queue lockup I reported > > > recently on the linux-block mailing list. Please consider these patches > > > for inclusion in the upstream kernel. > > > > just out of curiosity. Is this maybe related to similar stuff happening > > when CPUs are hot plugged - at least in that the stack gets stuck? Like > > in this thread here: > > https://www.mail-archive.com/linux-block@vger.kernel.org/msg06057.html > > > > Would be interesting, because we recently saw similar stuff happening. > > Hello Benjamin, > > My proposal is to repeat that test with Jens' for-next branch. If the issue > still occurs with that tree then please check the contents of > /sys/kernel/debug/block/*/mq/*/{dispatch,*/rq_list}. That will allow to > determine whether or not any block layer requests are still pending. If > running the command below resolves the deadlock then it means that a > trigger to run a block layer queue is still missing somewhere: > > for a in /sys/kernel/debug/block/*/mq/state; do echo run >$a;�done > > See also git://git.kernel.dk/linux-block.git. > Thx for the hint! I'll forward that and see if the affected folks are willing to reproduce. Beste Gr��e / Best regards, - Benjamin Block -- Linux on z Systems Development / IBM Systems & Technology Group IBM Deutschland Research & Development GmbH Vorsitz. AufsR.: Martina Koederitz / Gesch�ftsf�hrung: Dirk Wittkopp Sitz der Gesellschaft: B�blingen / Registergericht: AmtsG Stuttgart, HRB 243294