Commits
Chris Wilson committed db9f9203e27
drm/i915/userptr: Hold mmref whilst calling get-user-pages Holding a reference to the containing task_struct is not sufficient to prevent the mm_struct from being reaped under memory pressure. If this happens whilst we are calling get_user_pages(), explosions erupt - sometimes an immediate GPF, sometimes page flag corruption. To prevent the target mm from being reaped as we are reading from it, acquire a reference before we begin. Testcase: igt/gem_shrink/*userptr Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk> Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com> Cc: Michał Winiarski <michal.winiarski@intel.com> Cc: stable@vger.kernel.org Reviewed-by: Michał Winiarski <michal.winiarski@intel.com> Link: http://patchwork.freedesktop.org/patch/msgid/1459864801-28606-2-git-send-email-chris@chris-wilson.co.uk (cherry picked from commit 40313f0cd0b711a7a5905e5182422799e157d8aa) Signed-off-by: Jani Nikula <jani.nikula@intel.com>