Quoting Chris Wilson (2019-09-20 13:18:21)
> Since dropping the set-to-gtt-domain in commit a679f58d0510 ("drm/i915:
> Flush pages on acquisition"), we no longer mark the contents as dirty on
> a write fault. This has the issue of us then not marking the pages as
> dirty on releasing the buffer, which means the contents are not written
> out to the swap device (should we ever pick that buffer as a victim).
> Notably, this is visible in the dumb buffer interface used for cursors.
> Having updated the cursor contents via mmap, and swapped away, if the
> shrinker should evict the old cursor, upon next reuse, the cursor would
> be invisible.
Hmm, I think the dumb interface may be missing a few steps around the
place to ensure the contents are flushed.
-Chris
