Created attachment 127961 [details]
The whole GUI sometimes freezes permanently. The display shows no reactions to any events until I reboot the computer. Logging in by SSH I can see that the OS is at least partially working. Network traffic flows and I can read files. When I kill processes most of them terminate, but the images of their windows remain unchanged on the display. Some processes linger as zombies. When I run "reboot" the SSH session ends, and I can't log in again, but the system does not reboot. Only a hardware reset reboots the computer.
I don't have a reliable way of triggering a freeze, but it happens only when something is changing in the GUI, often when I resize a window or open a new window. It has never happened when I wasn't working on the local console. When opening a new window it looks like it's not quite done drawing the window decorations when it freezes.
The following appears in the system log:
Nov 13 20:05:36 hactar kernel: [drm] stuck on render ring
Nov 13 20:05:36 hactar kernel: [drm] GPU HANG: ecode 4:0:0x00ba6937, in Xorg , reason: Engine(s) hung, action: reset
Nov 13 20:05:36 hactar kernel: [drm] GPU hangs can indicate a bug anywhere in the entire gfx stack, including userspace.
Nov 13 20:05:36 hactar kernel: [drm] Please file a _new_ bug report on bugs.freedesktop.org against DRI -> DRM/Intel
Nov 13 20:05:36 hactar kernel: [drm] drm/i915 developers can then reassign to the right component if it's not a kernel issue.
Nov 13 20:05:36 hactar kernel: [drm] The gpu crash dump is required to analyze gpu hangs, so please always attach it.
Nov 13 20:05:36 hactar kernel: [drm] GPU crash dump saved to /sys/class/drm/card0/error
motherboard: Asus P5E-V HDMI
display connector: HDMI
distribution: Fedora 23
The permanent GUI freezes happen with Linux 4.6 and 4.7. Today it happened with Fedora's kernel-4.7.9-100.fc23. They do not happen with kernel-4.5.7-202.fc23.
Before Linux 4.6 the GUI would only freeze for a second or so. Then the screen went black for a moment, and then everything worked normally again except that the mouse pointer was invisible. To get the pointer back I had to lock and then unlock the console. This also happened only when something was changing in the GUI, often when I resized a window. Those symptoms began when I upgraded from Fedora 21 to Fedora 23, and continued until the first 4.6 kernel.
Other currently installed packages:
Please verify that you can reproduce this using the modesetting DDX. A known issue in xf86-video-intel may be causing your hang.
I think I eventually figured out what "the modesetting DDX" is. I think it's probably the same thing as "the modesetting Xorg driver" (which if I understand correctly does not perform any modesetting, because kernel drivers do that) that is discussed in this email thread:
I think that when I see many "modeset(0)" lines in Xorg.0.log, then the modesetting DDX is in use, whereas when I see many "intel(0)" and also these lines:
[ 76.406] (II) UnloadModule: "modesetting"
[ 76.406] (II) Unloading modesetting
then xf86-video-intel is in use.
However, I'm now running Fedora 25, and during a few weeks of opening, closing, moving and resizing windows I haven't been able to trigger a GPU hang, neither with the "modesetting" driver nor with the "intel" driver. It seems like the bug may have been fixed, or the probability that a hang will occur may have decreased.