Bug 82523

Created attachment 104522 [details]
/sys/class/drm/card0/error

I am using Ubuntu 14.04 on an Acer c720. Every couple of hours it will freeze for about five seconds, afterwards the framebuffer displays corrupt fonts in any window that may have been open. Closing and reopening has worked until now; I was fed up so I checked the kerne.log with grep drm and found:

Aug 12 15:09:30 jesse-Peppy kernel: [ 5843.976707] [drm] stuck on render ring
Aug 12 15:09:30 jesse-Peppy kernel: [ 5843.976715] [drm] GPU crash dump saved to /sys/class/drm/card0/error
Aug 12 15:09:30 jesse-Peppy kernel: [ 5843.976719] [drm] GPU hangs can indicate a bug anywhere in the entire gfx stack, including userspace.
Aug 12 15:09:30 jesse-Peppy kernel: [ 5843.976721] [drm] Please file a _new_ bug report on bugs.freedesktop.org against DRI -> DRM/Intel
Aug 12 15:09:30 jesse-Peppy kernel: [ 5843.976724] [drm] drm/i915 developers can then reassign to the right component if it's not a kernel issue.
Aug 12 15:09:30 jesse-Peppy kernel: [ 5843.976727] [drm] The gpu crash dump is required to analyze gpu hangs, so please always attach it.

I also found a thread on reddit (by accident) http://www.reddit.com/r/chrubuntu/comments/2d88dg/freezing_on_c720_ideas/
The poster there sent me his /sys/class/drm/card0/error output, so I am attaching both of ours.

It should also be noted that I was running the linux-next kernel yesterday, and this happend as well.

One more thing, as this is the Acer c720, there were a few kernel flags in grub that I used (and most people use) to make it run well with a kernel such as 3.13 (which we both have). Some of them might not be necessary in 3.16 (linux-next), but I left them in place, and I suspect that they may be the catalyst of the problem. They are:
GRUB_CMDLINE_LINUX_DEFAULT="add_efi_memmap boot=local noresume noswap i915.modeset=1 tpm_tis.force=1 tpm_tis.interrupts=0 nmi_watchdog=panic,lapic"

Thanks guys! I'll look into it as more as well, but I thought I should post it here as I finally have all of the info