On 11/23/21 18:00, Jason Gunthorpe wrote:

quoted

believe what you say and I trust your experience :) So could as well be
that on such a "special" (or not so special) systems there should be a
way to restrict it to privileged users only.

At this point RDMA is about as "special" as people running large
ZONE_MOVABLE systems, and the two are going to start colliding
heavily. The RDMA VFIO migration driver should be merged soon which
makes VMs using this stuff finally practical.

How does that work, I see the word migration, so does it cause pages to
be migrated out of ZONE_MOVABLE before they are pinned?
Similarly for io-uring we could be migrating pages to be pinned so that
the end up consolidated close together, and prevent pathologic
situations like in David's reproducer. IIRC that was a idea to do for
long-term pins in general.

Jason