[Intel-gfx] [PATCH] drm/i915: Mark contents as dirty on a write fault

[Matthew Auld]

On Fri, 20 Sep 2019 at 13:18, Chris Wilson <chris at chris-wilson.co.uk> wrote:
>
> 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.
>
> E.g. echo 80 > /proc/sys/kernel/sysrq ; echo f > /proc/sysrq-trigger
>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=111541
> Fixes: a679f58d0510 ("drm/i915: Flush pages on acquisition")
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Matthew Auld <matthew.william.auld at gmail.com>
> Cc: Ville Syrjälä <ville.syrjala at linux.intel.com>
> Cc: <stable at vger.kernel.org> # v5.2+
Reviewed-by: Matthew Auld <matthew.william.auld at gmail.com>