From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755602Ab3LEXQn (ORCPT ); Thu, 5 Dec 2013 18:16:43 -0500 Received: from ipmail04.adl6.internode.on.net ([150.101.137.141]:27978 "EHLO ipmail04.adl6.internode.on.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751699Ab3LEXQm (ORCPT ); Thu, 5 Dec 2013 18:16:42 -0500 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AtIHACEJoVJ5LHyk/2dsb2JhbABZgwe0LIVPgR4XdIIlAQEFJxMcIxAIAw4KCSUPBSUDIROIAcFLFxaOageEMwOYE4pMh0iDPSg Date: Fri, 6 Dec 2013 10:16:12 +1100 From: Dave Chinner To: Ming Lei Cc: linux-kernel@vger.kernel.org, Jens Axboe Subject: Re: [OOPS, 3.13-rc2] null ptr in dio_complete() Message-ID: <20131205231612.GQ10988@dastard> References: <20131203215940.GX10988@dastard> <20131204015837.GJ10988@dastard> <20131205222220.5d7f4a48@tom-ThinkPad-T410> <20131205212651.GP10988@dastard> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131205212651.GP10988@dastard> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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! Cheers, Dave. -- Dave Chinner david@fromorbit.com