From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bart Van Assche Subject: Re: [PATCH v4 0/6] Avoid that scsi-mq and dm-mq queue processing stalls sporadically Date: Wed, 12 Apr 2017 18:11:25 +0000 Message-ID: <1492020683.2764.9.camel@sandisk.com> References: <20170407181654.27836-1-bart.vanassche@sandisk.com> <20170412105538.GB22576@bblock-ThinkPad-W530> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <20170412105538.GB22576@bblock-ThinkPad-W530> Content-Language: en-US Content-ID: Sender: linux-block-owner@vger.kernel.org To: "bblock@linux.vnet.ibm.com" Cc: "linux-scsi@vger.kernel.org" , "linux-block@vger.kernel.org" , "axboe@kernel.dk" List-Id: linux-scsi@vger.kernel.org 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. >=20 > 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 >=20 > 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;=A0done See also git://git.kernel.dk/linux-block.git. Bart.=