Comment 13 for bug 451518

Ugh - happened to me too - after the latest kernel upgrade (don't know if it's related).
I'm running:
adrianp@frost:~$ uname -a
Linux frost 2.6.31-16-generic #53-Ubuntu SMP Tue Dec 8 04:01:29 UTC 2009 i686 GNU/Linux
adrianp@frost:~$ lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation 82Q35 Express Integrated Graphics Controller (rev 02)

The thing is - it seems to be crashing only when xscreensaver is running (I have some GL screensavers) - but it's not always reproductible. I have turned off dpms, but it doesn't help. I can login to the computer via ssh, but commands like xset can't run (start, but remain "hanged").

Here is some output from dmesg:
[176880.528048] INFO: task i915/0:315 blocked for more than 120 seconds.
[176880.528054] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[176880.528058] i915/0 D c08145c0 0 315 2 0x00000000
[176880.528066] f6991f04 00000046 f64e4b8c c08145c0 f64e4df8 c08145c0 dd47cd37 00009fbf
[176880.528079] c08145c0 c08145c0 f64e4df8 c08145c0 dd47bfb4 00009fbf c08145c0 eed81500
[176880.528090] f64e4b60 f697c414 f697c418 ffffffff f6991f30 c056fdd6 f6901920 f697c41c
[176880.528101] Call Trace:
[176880.528114] [<c056fdd6>] __mutex_lock_slowpath+0xc6/0x130
[176880.528120] [<c056fcf0>] mutex_lock+0x20/0x40
[176880.528150] [<f840ac0a>] i915_gem_retire_work_handler+0x2a/0x70 [i915]
[176880.528158] [<c0157a7e>] run_workqueue+0x6e/0x140
[176880.528181] [<f840abe0>] ? i915_gem_retire_work_handler+0x0/0x70 [i915]
[176880.528188] [<c0157bd8>] worker_thread+0x88/0xe0
[176880.528194] [<c015c280>] ? autoremove_wake_function+0x0/0x40
[176880.528200] [<c0157b50>] ? worker_thread+0x0/0xe0
[176880.528205] [<c015bf8c>] kthread+0x7c/0x90
[176880.528210] [<c015bf10>] ? kthread+0x0/0x90
[176880.528216] [<c0104007>] kernel_thread_helper+0x7/0x10

...and from messages:
Dec 17 14:23:54 localhost kernel: [176880.528058] i915/0 D c08145c0 0 315 2 0x00000000
Dec 17 14:23:54 localhost kernel: [176880.528066] f6991f04 00000046 f64e4b8c c08145c0 f64e4df8 c08145c0 dd47cd37 00009fbf
Dec 17 14:23:54 localhost kernel: [176880.528079] c08145c0 c08145c0 f64e4df8 c08145c0 dd47bfb4 00009fbf c08145c0 eed81500
Dec 17 14:23:54 localhost kernel: [176880.528090] f64e4b60 f697c414 f697c418 ffffffff f6991f30 c056fdd6 f6901920 f697c41c
Dec 17 14:23:54 localhost kernel: [176880.528101] Call Trace:
Dec 17 14:23:54 localhost kernel: [176880.528114] [<c056fdd6>] __mutex_lock_slowpath+0xc6/0x130
Dec 17 14:23:54 localhost kernel: [176880.528120] [<c056fcf0>] mutex_lock+0x20/0x40
Dec 17 14:23:54 localhost kernel: [176880.528150] [<f840ac0a>] i915_gem_retire_work_handler+0x2a/0x70 [i915]
Dec 17 14:23:54 localhost kernel: [176880.528158] [<c0157a7e>] run_workqueue+0x6e/0x140
Dec 17 14:23:54 localhost kernel: [176880.528181] [<f840abe0>] ? i915_gem_retire_work_handler+0x0/0x70 [i915]
Dec 17 14:23:54 localhost kernel: [176880.528188] [<c0157bd8>] worker_thread+0x88/0xe0
Dec 17 14:23:54 localhost kernel: [176880.528194] [<c015c280>] ? autoremove_wake_function+0x0/0x40
Dec 17 14:23:54 localhost kernel: [176880.528200] [<c0157b50>] ? worker_thread+0x0/0xe0
Dec 17 14:23:54 localhost kernel: [176880.528205] [<c015bf8c>] kthread+0x7c/0x90
Dec 17 14:23:54 localhost kernel: [176880.528210] [<c015bf10>] ? kthread+0x0/0x90
Dec 17 14:23:54 localhost kernel: [176880.528216] [<c0104007>] kernel_thread_helper+0x7/0x10

I will uninstall xscreensaver - hopefully I will no longer trigger the bug. I'll let you know if I find out something else...