[RFC PATCH v1 00/18] Provide a new two step DMA API mapping API

[Jason Gunthorpe]

On Fri, Jul 12, 2024 at 06:54:22AM +0200, Christoph Hellwig wrote:

> This is all purely hypothetical, and I'm happy to just check for it
> and reject it for it now.

I do know a patch set is cooking to allow mixing ZONE_DEVICE P2P and
anon memory in the same VMA ala HMM with transparent migration of
ZONE_DEVICE to anon.

In this situation userspace will be generating IO with no idea about
any P2P/!P2P boundaries.

Jason