Created attachment 684074 [details]
gdb backtrace of crash.

Description of problem:

Xorg randomly restarts killing all running apps. /var/log/messages shows:

Jan 21 19:14:31 pariah kernel: [34560.355691] [drm] nouveau 0000:02:00.0: nv50cal_space: -16
Jan 21 19:14:31 pariah kernel: [34560.559053] [drm] nouveau 0000:02:00.0: nv50cal_space: -16
Jan 21 19:14:31 pariah kernel: [34560.749163] [drm] nouveau 0000:02:00.0: nv50cal_space: -16
Jan 21 19:14:31 pariah kernel: [34560.939352] [drm] nouveau 0000:02:00.0: nv50cal_space: -16
Jan 21 19:14:31 pariah kernel: [34561.129519] [drm] nouveau 0000:02:00.0: nv50cal_space: -16
Jan 21 19:37:05 pariah abrtd: Directory 'ccpp-2013-01-21-19:37:03-1325' creation detected
Jan 21 19:37:05 pariah abrt[11118]: Saved core dump of pid 1325 (/usr/bin/Xorg) to /var/spool/
abrt/ccpp-2013-01-21-19:37:03-1325 (42532864 bytes)
Jan 21 19:37:08 pariah kernel: [35917.792025] [drm] nouveau 0000:02:00.0: Failed to idle channel 2.
Jan 21 19:37:08 pariah gnome-session[1521]: Gdk-WARNING: gnome-session: Fatal IO error 11 (Resource temporarily unavailable) on X server :0.#012
Jan 21 19:37:09 pariah systemd-logind[1119]: Removed session 2.
Jan 21 19:37:14 pariah systemd-logind[1119]: New session 12 of user gdm.
Jan 21 19:37:14 pariah systemd-logind[1119]: Linked /tmp/.X11-unix/X0 to /run/user/gdm/X11-display.
Jan 21 19:37:14 pariah abrtd: New problem directory /var/spool/abrt/ccpp-2013-01-21-19:37:03-1325, processing
Jan 21 19:37:15 pariah kernel: [35924.374838] [drm:drm_debugfs_create_files] *ERROR* Cannot create /sys/kernel/debug/dri/channel/4

Version-Release number of selected component (if applicable):

xorg-x11-server-Xorg-1.11.4-3.fc16

How reproducible: Occurred for the first time tonight but has occurred three times in the space of twenty minutes. 


Steps to Reproduce:
1. Login to Gnome, start emacs and shell. Type in Emacs for ten minutes. X restarts without warning.
2.
3.
  
Actual results:

X randomly freezes, then dumps core and restarts.

Expected results:

X should not restart.

Additional info: This computer is a laptop. For a few weeks I have had a 19in monitor connected to the VGA-in port and Gnome/Xorg happily recognised it and allowed me to have some of my programs shown on it. Yesterday I disconnected the monitor after updating Fedora with all the latest updates and then rebooting. It is only today, after the laptop lid was closed overnight, that the problem with X restarting has started to happen.

I am running  kernel 3.6.11-1.fc16.x86_64. xorg is xorg-x11-server-Xorg-1.11.4-3.fc16.

I have a full core dump which I can attach if needed, but at 40MB I did not want to attach it unnecessarily.