So parts of the reasons I've reassigned to amdgpu is that appa=
rently someone
also seen these corruptions when everything is rendered on amdgpu, and i915
only displays. And the display engine is definitely only accessing memory
directly, bypassing cpu caches.

Changing stuff on the kernel on the i915 side didn't help (on import we tre=
at
buffers as uncached and assume they're fully flushed). But we kinda
missed/didn't get around to testing the mesa caching mode overrides (which =
seem
to be wrong when texturing). So might need to move the bug to intel mesa (a=
nd
who knows what happened with the display issue, I guess we'll shrug that off
until confirmed with a video).

Aside: When exporting dma-buf from i915 we leave them in whatever caching m=
ode
is preferred by that gpu platform, which on recent big core is fully cached
(i.e. requires snooping). We still might need to somehow teach dma-buf
importers about whether they need to use snooping reads/writes (through a n=
ew
flag/function/whatever).