turn hmm migrate_vma upside down v3

[Jason Gunthorpe]

On Fri, Aug 16, 2019 at 08:51:41AM +0200, Christoph Hellwig wrote:
> Jason,
> 
> are you going to look into picking this up?  Unfortunately there is
> a hole pile in this area still pending, including the kvmppc secure
> memory driver from Bharata that depends on the work.

Done,

Lets see if Dan will comment on the pagemap part (looks
straightforward to me), and then after we grab that I will declare
hmm.git non-rebasing and Bharata can build his series upon it.

As a reminder, please do not send hmm.git inside another pull request
to Linus without making it very clear in that cover letter and Cc'ing
me. Thanks.

Regards,
Jason