Created attachment 162401 [details]
Photo of the visible part of backtrace

1. Start Rosegarden;
2. Issue "pmidi -p 128:0 anymidifile.mid" (i.e. try playing MIDI file into Rosegarden's MIDI input).

System freezes. Sometimes I see display updates, but not input or network accepted. Sometimes it behaves as if I hold "Enter" key. SysRQ's don't get though.

If "pmidi" is issued from text mode, the cursor stops blinking.

Sometimes I can do a few more input commands before the lockup.

In text mode, I also saw this message:

[  270.261869] [drm:i915_hangcheck_elapsed] *ERROR* Hangcheck timer elapsed... blitter ring idle

After waiting more I was other backtrace (attached image).