Comment 2 for bug 419328

more errors in dmesg trying to restart X via /etc/init.d/gdm restart does not work

[ 360.744203] INFO: task i915/0:841 blocked for more than 120 seconds.
[ 360.744219] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 360.744232] i915/0 D c080c380 0 841 2 0x00000000
[ 360.744253] f68a3f04 00000046 f68dc000 c080c380 f6806718 c080c380 e71988b2 00000020
[ 360.744282] c080c380 c080c380 f6806718 c080c380 00000000 00000020 c080c380 f5f75340
[ 360.744309] f6806480 f691c014 f691c018 ffffffff f68a3f30 c0568e26 c0737180 f691c01c
[ 360.744336] Call Trace:
[ 360.744365] [<c0568e26>] __mutex_lock_slowpath+0xc6/0x130
[ 360.744382] [<c0568d40>] mutex_lock+0x20/0x40
[ 360.744450] [<f824e94a>] i915_gem_retire_work_handler+0x2a/0x70 [i915]
[ 360.744483] [<c015311e>] run_workqueue+0x6e/0x140
[ 360.744539] [<f824e920>] ? i915_gem_retire_work_handler+0x0/0x70 [i915]
[ 360.744569] [<c0153278>] worker_thread+0x88/0xe0
[ 360.744590] [<c0157920>] ? autoremove_wake_function+0x0/0x40
[ 360.744610] [<c01531f0>] ? worker_thread+0x0/0xe0
[ 360.744623] [<c015762c>] kthread+0x7c/0x90
[ 360.744637] [<c01575b0>] ? kthread+0x0/0x90
[ 360.744654] [<c0103f17>] kernel_thread_helper+0x7/0x10
[ 360.744704] INFO: task Xorg:2480 blocked for more than 120 seconds.
[ 360.744714] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 360.744724] Xorg D c080c380 0 2480 2479 0x00400004
[ 360.744743] f5da3e28 00003082 00000000 c080c380 f662c168 c080c380 bddf3835 00000020
[ 360.744770] c080c380 c080c380 f662c168 c080c380 bddedbed 00000020 c080c380 f6712c40
[ 360.744798] f662bed0 f691c014 f691c018 ffffffff f5da3e54 c0568e26 00000000 f691c01c
[ 360.744824] Call Trace:
[ 360.744841] [<c0568e26>] __mutex_lock_slowpath+0xc6/0x130
[ 360.744857] [<c0568d40>] mutex_lock+0x20/0x40
[ 360.744914] [<f824ebcb>] i915_gem_throttle_ioctl+0x2b/0x70 [i915]
[ 360.744932] [<c01e43a5>] ? do_sync_readv_writev+0xb5/0xf0
[ 360.745003] [<f81466c0>] drm_ioctl+0x180/0x360 [drm]
[ 360.745093] [<f824eba0>] ? i915_gem_throttle_ioctl+0x0/0x70 [i915]
[ 360.745121] [<c02c4c4f>] ? security_file_permission+0xf/0x20
[ 360.745142] [<c01e463f>] ? rw_verify_area+0x5f/0xe0
[ 360.745157] [<c01e4a88>] ? rw_copy_check_uvector+0x78/0xf0
[ 360.745174] [<c01244f8>] ? default_spin_lock_flags+0x8/0x10
[ 360.745191] [<c015aaa5>] ? __remove_hrtimer+0x25/0x70
[ 360.745207] [<c015b303>] ? hrtimer_try_to_cancel+0x33/0x80
[ 360.745225] [<c0144b2e>] ? do_setitimer+0x23e/0x300
[ 360.745252] [<c01f1fa3>] vfs_ioctl+0x73/0x90
[ 360.745267] [<c01f2271>] do_vfs_ioctl+0x71/0x310
[ 360.745283] [<c0144c2b>] ? sys_setitimer+0x3b/0x90
[ 360.745297] [<c01f256f>] sys_ioctl+0x5f/0x80
[ 360.745312] [<c010334c>] syscall_call+0x7/0xb