ensure device private pages have an owner v2

[Jason Gunthorpe]

On Thu, Mar 19, 2020 at 08:16:33AM +0100, Christoph Hellwig wrote:
> On Wed, Mar 18, 2020 at 09:28:49PM -0300, Jason Gunthorpe wrote:
> > > Changes since v1:
> > >  - split out the pgmap->owner addition into a separate patch
> > >  - check pgmap->owner is set for device private mappings
> > >  - rename the dev_private_owner field in struct migrate_vma to src_owner
> > >  - refuse to migrate private pages if src_owner is not set
> > >  - keep the non-fault device private handling in hmm_range_fault
> > 
> > I'm happy enough to take this, did you have plans for a v3?
> 
> I think the only open question is if merging 3 and 4 might make sense.
> It's up to you if you want it resent that way or not.

Okay, I kept it as is and elaborated the commit messages a bit based
on the discussion

It doesn't seem like the changes outside hmm are significant enough to
need more acks

Thanks,
Jason