[v3.7 Regression] [SCSI] sd: Implement support for WRITE SAME

Mike Snitzer snitzer at redhat.com
Fri Dec 14 21:11:59 UTC 2012

On Fri, Dec 14 2012 at  3:30pm -0500,
Joseph Salisbury <joseph.salisbury at canonical.com> wrote:

> Hi Martin,
> A bug was opened against the Ubuntu kernel[0].  After a kernel
> bisect, it was found that reverting the following commit resolved
> this bug:
> commit 5db44863b6ebbb400c5e61d56ebe8f21ef48b1bd
> Author: Martin K. Petersen <martin.petersen at oracle.com>
> Date:   Tue Sep 18 12:19:32 2012 -0400
> [SCSI] sd: Implement support for WRITE SAME
> The regression was introduced as of v3.7-rc7.
> The bug can be reproduced with the following commands, which will
> operate on a virtual scsi_debug device, so they won't change any
> data on the test system. However, this will completely crash the
> system:
> sudo modprobe scsi_debug
> sudo luksformat -t ext4 /dev/sdb <- Or whatever device gets assigned
> after inserting scsi_debug.
> sudo cryptsetup luksOpen /dev/sdb treasure
> Everything works fine up to here, but the following will cause the crash:
> sudo mount /dev/mapper/treasure /mnt
> The bug can be reproduced on bare metal, in a VM and on i386 or amd64.
> I see that you are the author of this patch, so I wanted to run this
> by you.  I was thinking of requesting a revert for v3.7, but I
> wanted to get your feedback first.
> Thanks,
> Joe
> [0] https://bugs.launchpad.net/bugs/1089818

The WRITE SAME change was introduced long before v3.7-rc7.  I think your
bisect is somehow wrong.

Milan Broz recently pointed out issues he found with luks when using a
late 3.7-rc (rc7 afaik).  Linus fixed that issue with this commit (which
landed in the final v3.7):

That may not be _the_ problem though.  But have you tried the final


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