Re: virtio-scsi issues duplicate tags when async_abort is enabled

[Greg KH <greg@kroah.com>]

On Fri, Jun 13, 2014 at 12:18:25PM -0700, James Bottomley wrote:
> On Fri, 2014-06-13 at 12:15 -0700, Venkatesh Srinivas wrote:
> > On Fri, Jun 13, 2014 at 12:09 PM, James Bottomley
> > <James.Bottomley@hansenpartnership.com> wrote:
> > > On Fri, 2014-06-13 at 11:52 -0700, Christoph Hellwig wrote:
> > >> On Fri, Jun 13, 2014 at 10:58:22AM -0700, Venkatesh Srinivas wrote:
> > >> > CC-ing stable as 3.14 and 3.15 are affected; a conservative fix is to
> > >> > enable no_async_abort until the problem is better-understood.
> > >>
> > >> No patch attached.  Nevermind this is not a consdervative fix, but a
> > >> band aid.  The proper fix is to figure out what's actually going on
> > >> here.
> > >>
> > >> >From your trace above it very much looks like a double completion of
> > >> some sort.
> > >>
> > >> I've looked at the virtio-scsi code a bit, and one odd thing it does
> > >> that comes in handy here is that it doesn't really use a traditional
> > >> tag, but rather the address of the scsi command.
> > >
> > > What kernel version?  This is the exact signature of the original USB
> > > REQUEST_SENSE problem.
> > 
> > Mix of kernels, all 3.14-based. Debian 3.14-0.bpo, Gentoo's 3.14,
> > upstream from git as of a few days ago.
> > 
> > Distribution 3.13 and earlier kernels (Debian's 3.2.0-4, Debian
> > 3.13-0.bpo.1, Gentoo 3.13.6) do not hit this issue with the same
> > workload.
> 
> OK, I've no idea what's in distro kernels, so you're looking for this
> fix:
> 
> commit d555a2abf3481f81303d835046a5ec2c4fb3ca8e
> Author: James Bottomley <JBottomley@Parallels.com>
> Date:   Fri Mar 28 10:50:17 2014 -0700
> 
>     [SCSI] Fix spurious request sense in error handling
> 
> It went into v3.15-rc3.  It looks like it wasn't backported to stable.

That would be because no one asked it to be backported, why didn't you
tag it as such?

greg k-h