From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Date: Thu, 21 Jun 2018 09:01:43 -0600 From: Keith Busch To: "jianchao.wang" Cc: Christoph Hellwig , axboe@kernel.dk, martin.petersen@oracle.com, josef@toxicpanda.com, ulf.hansson@linaro.org, linux-block@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/5]stop normal completion path entering a timeout req Message-ID: <20180621150143.GA26712@localhost.localdomain> References: <1529500964-28429-1-git-send-email-jianchao.w.wang@oracle.com> <20180620181601.GA24145@localhost.localdomain> <20180621081900.GA5183@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: List-ID: On Thu, Jun 21, 2018 at 09:13:30PM +0800, jianchao.wang wrote: > Hi Christoph > > On 06/21/2018 04:19 PM, Christoph Hellwig wrote: > > On Thu, Jun 21, 2018 at 09:43:26AM +0800, jianchao.wang wrote: > >> So we have to preserve the ability of block layer that it could prevent > >> IO completion path from entering a timeout request. > >> > >> With scsi-debug module, I tried to simulate a scenario where timeout and IO > >> completion path could occur concurrently, the system ran into crash easily. > > > > Trace, please. With the latest kernel. I'm not saying that there > > is nothing to fix, but the mode of never completing once timeout > > requests as currently done is SCSI is clearly broken. > > > > Sorry, I don't quite get your point. > Do you mean we should do the modification in the scsi layer ? I think it would just be helpful to start with the stack trace of your observed crash + the reproduction steps so the problem (and hopefully a solution) can be better understood.