From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754806AbdEKC4A (ORCPT ); Wed, 10 May 2017 22:56:00 -0400 Received: from mail-pf0-f182.google.com ([209.85.192.182]:36496 "EHLO mail-pf0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754723AbdEKCz7 (ORCPT ); Wed, 10 May 2017 22:55:59 -0400 Subject: Re: Lockdep splat involving all_q_mutex To: paulmck@linux.vnet.ibm.com, peterz@infradead.org References: <20170510223407.GA7122@linux.vnet.ibm.com> Cc: linux-kernel@vger.kernel.org, rostedt@goodmis.org, tglx@linutronix.de From: Jens Axboe Message-ID: <10e33da8-316d-9f51-b608-91ff7c68e2fa@kernel.dk> Date: Wed, 10 May 2017 20:55:54 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: <20170510223407.GA7122@linux.vnet.ibm.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/10/2017 04:34 PM, Paul E. McKenney wrote: > Hello! > > I got the lockdep splat shown below during some rcutorture testing (which > does CPU hotplug operations) on mainline at commit dc9edaab90de ("Merge > tag 'acpi-extra-4.12-rc1' of git://git.kernel.org/.../rafael/linux-pm"). > My kneejerk reaction was just to reverse the "mutex_lock(&all_q_mutex);" > and "get_online_cpus();" in blk_mq_init_allocated_queue(), but then > I noticed that commit eabe06595d62 ("block/mq: Cure cpu hotplug lock > inversion") just got done moving these two statements in the other > direction. The problem is that that patch got merged too early, as it only fixes a lockdep splat with the cpu hotplug rework. Fix is coming Linus' way, it's in my for-linus tree. -- Jens Axboe