From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753604AbaIXQKb (ORCPT ); Wed, 24 Sep 2014 12:10:31 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:19474 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753458AbaIXQK3 (ORCPT ); Wed, 24 Sep 2014 12:10:29 -0400 Date: Wed, 24 Sep 2014 10:10:25 -0600 From: Jens Axboe To: CC: Subject: [GIT PULL] One last block fix Message-ID: <20140924161025.GA25787@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline X-Originating-IP: [192.168.57.29] X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.12.52,1.0.28,0.0.0000 definitions=2014-09-24_07:2014-09-24,2014-09-24,1970-01-01 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 kscore.is_bulkscore=0.000562873213808546 kscore.compositescore=0 circleOfTrustscore=33.2965958620397 compositescore=0.9989857498195 urlsuspect_oldscore=0.9989857498195 suspectscore=3 recipient_domain_to_sender_totalscore=0 phishscore=0 bulkscore=0 kscore.is_spamscore=0 recipient_to_sender_totalscore=0 recipient_domain_to_sender_domain_totalscore=62764 rbsscore=0.9989857498195 spamscore=0 recipient_to_sender_domain_totalscore=0 urlsuspectscore=0.9 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=7.0.1-1402240000 definitions=main-1409240164 X-FB-Internal: deliver Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Linus, We've had an issue with scsi-mq where probing takes forever. This was bisected down to the percpu changes for blk_mq_queue_enter(), and the fact we now suffer an RCU grace period when killing a queue. SCSI creates and destroys tons of queues, so this let to 10s of seconds of stalls at boot for some. Tejun has a real fix for this, but it's too involved for 3.17. So this is a temporary workaround to expedite the queue killing until we can fold in the real fix for 3.18 when that merge window opens. Please pull! git://git.kernel.dk/linux-block.git for-linus for you to fetch changes up to 0a30288da1aec914e158c2d7a3482a85f632750f: blk-mq, percpu_ref: implement a kludge for SCSI blk-mq stall during probe (2014-09-24 08:29:36 -0600) ---------------------------------------------------------------- Tejun Heo (1): blk-mq, percpu_ref: implement a kludge for SCSI blk-mq stall during probe block/blk-mq.c | 11 ++++++++++- include/linux/percpu-refcount.h | 1 + lib/percpu-refcount.c | 16 ++++++++++++++++ 3 files changed, 27 insertions(+), 1 deletion(-) -- Jens Axboe