From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933865AbbDQPsQ (ORCPT ); Fri, 17 Apr 2015 11:48:16 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:48795 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932514AbbDQPsO (ORCPT ); Fri, 17 Apr 2015 11:48:14 -0400 Message-ID: <55312B38.8050701@fb.com> Date: Fri, 17 Apr 2015 09:48:08 -0600 From: Jens Axboe User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: Dave Jones , , Subject: Re: [GIT PULL] Followup single fix for block IO core pull References: <20150417151201.GA9330@kernel.dk> <20150417154148.GA8885@codemonkey.org.uk> <55312A7C.70602@fb.com> In-Reply-To: <55312A7C.70602@fb.com> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.54.13] X-Proofpoint-Spam-Reason: safe X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.13.68,1.0.33,0.0.0000 definitions=2015-04-17_06:2015-04-17,2015-04-17,1970-01-01 signatures=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/17/2015 09:45 AM, Jens Axboe wrote: > On 04/17/2015 09:41 AM, Dave Jones wrote: >> On Fri, Apr 17, 2015 at 09:12:01AM -0600, Jens Axboe wrote: >> > Hi Linus, >> > >> > A commit in the previous pull request introduce a regression. So far >> > only observed on qemu-sparc64, but it's a general bug. Please pull >> this >> > single fix to rectify that, thanks. >> >> I hit the same bug on two x86 boxes, bare-metal. >> Reverting the commit Guenter pointed out made them boot again, >> so definitely not sparc/qemu specific in any way. >> >> I suspect the only reason more people didn't see it is that not >> everyone is running with the mq-by-default config option yet ? > > It is puzzling. I ran it on several boxes, both multi queue and not, and > both single mq queues and multiple. But the code is clearly wrong. So > yeah, it's not sparc64 specific in any way. My initial thought was that > this was another issue related to sparse CPU ids, but that's not the > case. It's a plain bug, unfortunately. It's the pre morning coffee issue, looks like. All my test boxes end up having >= map->bits_per_word CPUs, so the test cases never ran into the round down issue. -- Jens Axboe