GPF on 0xdead000000000100 in nvme_map_data - Linux 5.9.9

[Roger Pau Monné]

On Fri, Dec 04, 2020 at 01:20:54PM +0100, Marek Marczykowski-Górecki wrote:
> On Fri, Dec 04, 2020 at 01:08:03PM +0100, Christoph Hellwig wrote:
> > On Fri, Dec 04, 2020 at 12:08:47PM +0100, Marek Marczykowski-Górecki wrote:
> > > culprit: 
> > > 
> > > commit 9e2369c06c8a181478039258a4598c1ddd2cadfa
> > > Author: Roger Pau Monne <roger.pau at citrix.com>
> > > Date:   Tue Sep 1 10:33:26 2020 +0200
> > > 
> > >     xen: add helpers to allocate unpopulated memory
> > >     
> > > I'm adding relevant people and xen-devel to the thread.
> > > For completeness, here is the original crash message:
> > 
> > That commit definitively adds a new ZONE_DEVICE user, so it does look
> > related.  But you are not running on Xen, are you?
> 
> I am. It is Xen dom0.

I'm afraid I'm on leave and won't be able to look into this until the
beginning of January. I would guess it's some kind of bad
interaction between blkback and NVMe drivers both using ZONE_DEVICE?

Maybe the best is to revert this change and I will look into it when
I get back, unless someone is willing to debug this further.

Thanks, Roger.