[PATCH 1/2] mm: handle multiple owners of device private pages in migrate_vma

[Jason Gunthorpe]

On Mon, Mar 16, 2020 at 06:52:58PM +0100, Christoph Hellwig wrote:
> Add a new opaque owner field to struct dev_pagemap, which will allow
> the hmm and migrate_vma code to identify who owns ZONE_DEVICE memory,
> and refuse to work on mappings not owned by the calling entity.

Using a pointer seems like a good solution to me.

Is this a bug fix? What is the downside for migrate on pages it
doesn't work? I'm not up to speed on migrate..

Jason