I decided not to send it to stable since problem was only observed on 4.11 but it is probably endemic to all GEN2 VM's -----Original Message----- From: Joseph Salisbury [mailto:joseph.salisbury@xxxxxxxxxxxxx] Sent: Tuesday, March 28, 2017 7:29 AM To: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>; Long Li <longli@xxxxxxxxxxxxx> Cc: KY Srinivasan <kys@xxxxxxxxxxxxx>; Martin K. Petersen <martin.petersen@xxxxxxxxxx>; Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>; jejb@xxxxxxxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx; linux-scsi <linux-scsi@xxxxxxxxxxxxxxx>; LKML <linux-kernel@xxxxxxxxxxxxxxx>; stable@xxxxxxxxxxxxxxx; Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> 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 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 <stephen@xxxxxxxxxxxxxxxxxx> > 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 <sthemmin@xxxxxxxxxxxxx> > Reviewed-by: K. Y. Srinivasan <kys@xxxxxxxxxxxxx> > Reviewed-by: Christoph Hellwig <hch@xxxxxx> > Signed-off-by: Martin K. Petersen <martin.petersen@xxxxxxxxxx> > > -----Original Message----- > From: Joseph Salisbury [mailto:joseph.salisbury@xxxxxxxxxxxxx] > Sent: Monday, March 27, 2017 1:22 PM > To: Long Li <longli@xxxxxxxxxxxxx> > Cc: KY Srinivasan <kys@xxxxxxxxxxxxx>; Martin K. Petersen <martin.petersen@xxxxxxxxxx>; Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>; Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>; jejb@xxxxxxxxxxxxxxxxxx; devel@xxxxxxxxxxxxxxxxxxxxxx; linux-scsi <linux-scsi@xxxxxxxxxxxxxxx>; LKML <linux-kernel@xxxxxxxxxxxxxxx>; stable@xxxxxxxxxxxxxxx; Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> > 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 <longli@xxxxxxxxxxxxx> > 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 > > Hi Stephen, Thanks again for pointing out commit f1c635b439a5c01776fe3a25b1e2dc546ea82e6f. It does indeed fix the bug. I noticed the commit was not cc'd to stable. Would it be possible to do that? Thanks, Joe