From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757547Ab3LFQrF (ORCPT ); Fri, 6 Dec 2013 11:47:05 -0500 Received: from merlin.infradead.org ([205.233.59.134]:52226 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756540Ab3LFQrD (ORCPT ); Fri, 6 Dec 2013 11:47:03 -0500 Message-ID: <52A1FF49.6090801@kernel.dk> Date: Fri, 06 Dec 2013 09:46:01 -0700 From: Jens Axboe User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.1.1 MIME-Version: 1.0 To: Dave Chinner , Ming Lei CC: linux-kernel@vger.kernel.org Subject: Re: [OOPS, 3.13-rc2] null ptr in dio_complete() References: <20131203215940.GX10988@dastard> <20131204015837.GJ10988@dastard> <20131205222220.5d7f4a48@tom-ThinkPad-T410> <20131205212651.GP10988@dastard> <20131205231612.GQ10988@dastard> In-Reply-To: <20131205231612.GQ10988@dastard> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/05/2013 04:16 PM, Dave Chinner wrote: > On Fri, Dec 06, 2013 at 08:26:51AM +1100, Dave Chinner wrote: >> On Thu, Dec 05, 2013 at 10:22:20PM +0800, Ming Lei wrote: >>> On Wed, 4 Dec 2013 12:58:38 +1100 >>> Dave Chinner wrote: >>> >>>> >>>> And I just hit this from running xfs_repair which is doing >>>> multithreaded direct IO directly on /dev/vdc: >> ..... >>>> So this is looking like another virtio+blk_mq problem.... >>> >>> This one might be caused by using-after-'free' request because the freed >>> request may be allocated to another CPU immediately, and the below patch >>> may be helpful, would you mind testing it? >>> >>> diff --git a/block/blk-mq.c b/block/blk-mq.c >>> index 6875736..2358bdf 100644 >>> --- a/block/blk-mq.c >>> +++ b/block/blk-mq.c >>> @@ -311,12 +311,12 @@ void blk_mq_complete_request(struct request *rq, int error) >>> >>> blk_account_io_completion(rq, bytes); >>> >>> + blk_account_io_done(rq); >>> + >>> if (rq->end_io) >>> rq->end_io(rq, error); >>> else >>> blk_mq_free_request(rq); >>> - >>> - blk_account_io_done(rq); >>> } >>> >>> void __blk_mq_end_io(struct request *rq, int error) >> >> Testing it now. I'll let you know how it goes in couple of hours. > > Ok, this looks like it is working correctly. The read/write io stats > are now working properly, too. Thanks for finding the problem > quickly! Great, thanks for testing, Dave. The fix is now in Linus' tree. -- Jens Axboe