Quoting Daniel Vetter (2017-10-31 16:38:26)
On Tue, Oct 31, 2017 at 03:28:01PM +0200, Ville Syrjälä wrote:
On Tue, Oct 31, 2017 at 11:55:35AM +0000, Chris Wilson wrote:
To acquire all modeset locks requires a ww_ctx to be allocated. As this is the legacy path and the allocation small, to reduce the changes required (and complex untested error handling) to the legacy drivers, we simply assume that the allocation succeeds. At present, it relies on the too-small-to-fail rule, but syzbot found that by injecting a failure here we would hit the WARN. Document that this allocation must succeed with __GFP_NOFAIL.
Note that for atomic drivers at least all the core/helper paths are fixed up correctly. But e.g. i915 has still plenty of callsites in its own code, mostly debugfs.
Reported-by: syzbot (syzkaller) Signed-off-by: Chris Wilson chris@chris-wilson.co.uk Cc: Daniel Vetter daniel.vetter@ffwll.ch
Reviewed-by: Ville Syrjälä ville.syrjala@linux.intel.com
Applied, thanks.
Just curious as it hasn't shown up in drm-tip yet, so I'm worrying if it found a crack to hide in. -Chris