Created attachment 98395 [details] dmesg If GPU blacklist is disabled in Chromium (on chrome://flags; so hardware accelerated rendering become enabled, judging from chrome://gpu) GPU sometimes lockup on just opening new tab (at least one time per day). After lockup I observe same behaviour like in Bug 77892 - reset happens but X is unresponsive except mouse. Radeon HD 6620G, Kubuntu 14.04 x86_64, Linux 3.15rc3, X.Org Server 1.15.1, libdrm 2.4.54+git1405030630.5126fc, Mesa 10.3~git1405030730.64c467, radeon driver 7.3.99+git1405030730.be1469. As I remember, this behaviour (GPU hang on opening new tab) introduced since Linux 3.15.
Created attachment 98396 [details] Xorg log
(In reply to comment #2) > As I remember, this behaviour (GPU hang on opening new tab) introduced since > Linux 3.15. Can you confirm that, and if the problem still doesn't occur with an older kernel, bisect?
> Can you confirm that, and if the problem still doesn't occur with an older kernel Yes, it doesn't occur with 3.14.3. > bisect Unfortunately, no.
Created attachment 100644 [details] lockup While GPU lockup doesn't happen anymore on opening new tab in Chromium, two other lockups happened for me with 3.15rc7 (system idle, Firefox with simple page without any video or HTML5 animation was opened; after three days of uptime) and 3.15rc8 (while fullscreen video playback in VLC, OpenGL GLX output; after five days of uptime). On latest lockup system become inaccessible via ssh (however cursor is still moving). Please look into attached log. Do I need to open another bugreport, to report this SUMO lockups with 3.15 that wasn't reproducible with 3.14, or add more information here is fine?
Not reproducible anymore with current kernel, Mesa, etc.
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