On Thu, 4 May 2017 12:33:42 -0700 Greg KH <greg@xxxxxxxxx> wrote: > On Wed, May 03, 2017 at 03:56:32PM -0700, Stephen Hemminger wrote: > > From: Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx> > > > > commit f1c635b439a5c01776fe3a25b1e2dc546ea82e6f upstream > > > > 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 > > 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 which works correctly. > > > > 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> > > --- > > drivers/scsi/storvsc_drv.c | 27 +++++++++++++++++---------- > > 1 file changed, 17 insertions(+), 10 deletions(-) > > I've queued this up, but it's interesting how you deleted the changelog > comments here saying this was only needed for 4.11 and no older kernels > :) At the time I only had reports of problem with 4.11. But others ran into issue with 4.10 and 4.9