From mboxrd@z Thu Jan 1 00:00:00 1970 From: Benjamin Block Subject: Re: [PATCH v4 0/6] Avoid that scsi-mq and dm-mq queue processing stalls sporadically Date: Thu, 13 Apr 2017 14:23:58 +0200 Message-ID: <20170413122358.GH22576@bblock-ThinkPad-W530> 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 Content-Transfer-Encoding: 8bit Return-path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:53428 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752908AbdDMMYH (ORCPT ); Thu, 13 Apr 2017 08:24:07 -0400 Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v3DCNf6K120110 for ; Thu, 13 Apr 2017 08:24:06 -0400 Received: from e06smtp10.uk.ibm.com (e06smtp10.uk.ibm.com [195.75.94.106]) by mx0a-001b2d01.pphosted.com with ESMTP id 29t5cmuh9q-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 13 Apr 2017 08:24:06 -0400 Received: from localhost by e06smtp10.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 13 Apr 2017 13:24:03 +0100 Received: from d06av24.portsmouth.uk.ibm.com (d06av24.portsmouth.uk.ibm.com [9.149.105.60]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v3DCO0ug17695074 for ; Thu, 13 Apr 2017 12:24:00 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 61F6642041 for ; Thu, 13 Apr 2017 13:23:05 +0100 (BST) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 410BA42042 for ; Thu, 13 Apr 2017 13:23:05 +0100 (BST) Received: from bblock-ThinkPad-W530 (unknown [9.152.212.69]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP for ; Thu, 13 Apr 2017 13:23:05 +0100 (BST) Content-Disposition: inline In-Reply-To: <1492020683.2764.9.camel@sandisk.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Bart Van Assche Cc: "linux-scsi@vger.kernel.org" , "linux-block@vger.kernel.org" , "axboe@kernel.dk" 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 Grüße / Best regards, - Benjamin Block -- Linux on z Systems Development / IBM Systems & Technology Group IBM Deutschland Research & Development GmbH Vorsitz. AufsR.: Martina Koederitz / Geschäftsführung: Dirk Wittkopp Sitz der Gesellschaft: Böblingen / Registergericht: AmtsG Stuttgart, HRB 243294