Created attachment 107083 [details] /i915_error_state in syslog I got (ThinkPAd T420, stable Gentoo) : Aug 2 18:41:42 n22 kernel: [drm:i915_hangcheck_hung] *ERROR* Hangcheck timer elapsed... GPU hung Aug 2 18:41:42 n22 kernel: [drm] capturing error event; look for more information in /sys/kernel/debug/dri/0/i915_error_state Aug 2 18:41:42 n22 kernel: [drm:kick_ring] *ERROR* Kicking stuck semaphore on render ring Aug 2 18:41:42 n22 kernel: [drm:__gen6_gt_force_wake_get] *ERROR* Timed out waiting for forcewake old ack to clear.
*** This bug has been marked as a duplicate of bug 53571 ***