From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752641AbdC0WZy (ORCPT ); Mon, 27 Mar 2017 18:25:54 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:56548 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752443AbdC0WZq (ORCPT ); Mon, 27 Mar 2017 18:25:46 -0400 Subject: Re: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] scsi: storvsc: properly set residual data length on errors To: Stephen Hemminger , Long Li References: <5df6cd65-92d5-e4c5-56e3-771643f86861@canonical.com> Cc: KY Srinivasan , "Martin K. Petersen" , Haiyang Zhang , "jejb@linux.vnet.ibm.com" , "devel@linuxdriverproject.org" , linux-scsi , LKML , "stable@vger.kernel.org" , Greg KH From: Joseph Salisbury Message-ID: <4b82a87c-4ee7-f653-8ca0-2f179abc17f8@canonical.com> Date: Mon, 27 Mar 2017 18:25:40 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/27/2017 06:14 PM, Stephen Hemminger wrote: > Are you sure the real problem is not the one fixed by this commit? > > commit f1c635b439a5c01776fe3a25b1e2dc546ea82e6f > Author: Stephen Hemminger > Date: Tue Mar 7 09:15:53 2017 -0800 > > scsi: storvsc: Workaround for virtual DVD SCSI version > > Hyper-V host emulation of SCSI for virtual DVD device reports SCSI > version 0 (UNKNOWN) but is still capable of supporting REPORTLUN. > > Without this patch, a GEN2 Linux guest on Hyper-V will not boot 4.11 > successfully with virtual DVD ROM device. What happens is that the SCSI > scan process falls back to doing sequential probing by INQUIRY. But the > storvsc driver has a previous workaround that masks/blocks all errors > reports from INQUIRY (or MODE_SENSE) commands. This workaround causes > the scan to then populate a full set of bogus LUN's on the target and > then sends kernel spinning off into a death spiral doing block reads on > the non-existent LUNs. > > By setting the correct blacklist flags, the target with the DVD device > is scanned with REPORTLUN and that works correctly. > > Patch needs to go in current 4.11, it is safe but not necessary in older > kernels. > > Signed-off-by: Stephen Hemminger > Reviewed-by: K. Y. Srinivasan > Reviewed-by: Christoph Hellwig > Signed-off-by: Martin K. Petersen > > -----Original Message----- > From: Joseph Salisbury [mailto:joseph.salisbury@canonical.com] > Sent: Monday, March 27, 2017 1:22 PM > To: Long Li > Cc: KY Srinivasan ; Martin K. Petersen ; Haiyang Zhang ; Stephen Hemminger ; jejb@linux.vnet.ibm.com; devel@linuxdriverproject.org; linux-scsi ; LKML ; stable@vger.kernel.org; Greg KH > Subject: [REGRESSION][Stable][v3.12.y][v4.4.y][v4.9.y][v4.10.y][v4.11-rc1] scsi: storvsc: properly set residual data length on errors > > Hi Long Li, > > A kernel bug report was opened against Ubuntu [0]. After a kernel > bisect, it was found that reverting the following commit resolved this bug: > > commit 40630f462824ee24bc00d692865c86c3828094e0 > Author: Long Li > Date: Wed Dec 14 18:46:03 2016 -0800 > > scsi: storvsc: properly set residual data length on errors > > > The regression was introduced in mainline as of v4.11-rc1. It was also > cc'd to stable and has landed in v3.12.y, v4.4.y, v4.9.y and v4.10.y. > > > This regression seems pretty severe since it's preventing virtual > machines from booting. It's affecting a couple of users so far. I was > hoping to get your feedback, since you are the patch author. Do you > think gathering any additional data will help diagnose this issue, or > would it be best to submit a revert request? > > > Thanks, > > Joe > > > [0] http://pad.lv/1674635 > > Thanks for the pointer, Stephen. I'll have this patch tested and respond with the results. Joe