For drm_gem_object_unreference callers are required to hold
dev->struct_mutex, which these paths don't. Enforcing this requirement
has become a bit more strict with
commit ef4c6270bf
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Thu Oct 15 09:36:25 2015 +0200
drm/gem: Check locking in drm_gem_object_unreference
Cc: Thierry Reding <thierry.reding@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Thierry Reding <treding@nvidia.com>