On Fri, Feb 05, 2021 at 04:39:47PM +0100, Daniel Vetter wrote: > > And again, for slightly older hardware, without pinning to VRAM there is > > no way to use this solution here for peer-to-peer. So I'm glad to see that > > so far you're not ruling out the pinning option. > > Since HMM and ZONE_DEVICE came up, I'm kinda tempted to make ZONE_DEVICE > ZONE_MOVEABLE (at least if you don't have a pinned vram contigent in your > cgroups) or something like that, so we could benefit from the work to make > sure pin_user_pages and all these never end up in there? ZONE_DEVICE should already not be returned from GUP. I've understood in the hmm casse the idea was a CPU touch of some ZONE_DEVICE pages would trigger a migration to CPU memory, GUP would want to follow the same logic, presumably it comes for free with the fault handler somehow Jason
