I have been experiencing this issue on 2.6.35-rc3 when a bunch of kernel debug options are enabled - let me know if you'd like the .config (tuned for an Intel desktop board). It reproduces reliably usually within an hour of activity and we get a similar signature [1] to other reports.

Commit e552eb7038a36d9b18860f525aa02875e313fe16 doesn't seem to address the issue, as this commit was introduced in 2.6.34.

--- [1]

INFO: task i915:774 blocked for more than 120 seconds.

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

i915          D ffff88010f0ba610  6280   774      2 0x00000000

 ffff88010f22dcb0 0000000000000086 ffff88010e742a00 ffff88010f0ba610

 ffff88010f22dfd8 00000000001d4440 ffff88010f22dfd8 ffff88010f0ba610

 00000000001d4440 00000000001d4440 ffff88010f22dfd8 00000000001d4440

Call Trace:

 [<ffffffff813a41ba>] ? intel_idle_update+0x4a/0x220

 [<ffffffff816425fa>] mutex_lock_nested+0x1ea/0x4c0

 [<ffffffff813a41ba>] ? intel_idle_update+0x4a/0x220

 [<ffffffff813a41ba>] ? intel_idle_update+0x4a/0x220

 [<ffffffff81644d03>] ? _raw_spin_unlock_irqrestore+0x53/0xa0

 [<ffffffff813a4170>] ? intel_idle_update+0x0/0x220

 [<ffffffff813a41ba>] intel_idle_update+0x4a/0x220

 [<ffffffff813a4170>] ? intel_idle_update+0x0/0x220

 [<ffffffff81069b20>] worker_thread+0x220/0x390

 [<ffffffff81069ace>] ? worker_thread+0x1ce/0x390

 [<ffffffff8108475d>] ? trace_hardirqs_on+0xd/0x10

 [<ffffffff8106eb70>] ? autoremove_wake_function+0x0/0x40

 [<ffffffff81069900>] ? worker_thread+0x0/0x390

 [<ffffffff8106e65e>] kthread+0xae/0xc0

 [<ffffffff81004024>] kernel_thread_helper+0x4/0x10

 [<ffffffff81645114>] ? restore_args+0x0/0x30

 [<ffffffff8106e5b0>] ? kthread+0x0/0xc0

 [<ffffffff81004020>] ? kernel_thread_helper+0x0/0x10

INFO: lockdep is turned off.

INFO: task Xorg:2004 blocked for more than 120 seconds.

"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.

Xorg          D ffffffff8180a360  4608  2004   1936 0x00400004

 ffff8801112d5c58 0000000000000086 ffff8801112d5bd8 ffffffffffffffff

 ffff8801112d5fd8 00000000001d4440 ffff8801112d5fd8 ffff8801078f0000

 00000000001d4440 00000000001d4440 ffff8801112d5fd8 00000000001d4440

Call Trace:

 [<ffffffff813958fb>] ? i915_gem_throttle_ioctl+0x3b/0x90

 [<ffffffff816425fa>] mutex_lock_nested+0x1ea/0x4c0

 [<ffffffff813958fb>] ? i915_gem_throttle_ioctl+0x3b/0x90

 [<ffffffff814f27f5>] ? sock_aio_write+0x125/0x140

 [<ffffffff813958fb>] ? i915_gem_throttle_ioctl+0x3b/0x90

 [<ffffffff813958fb>] i915_gem_throttle_ioctl+0x3b/0x90

 [<ffffffff8137734a>] drm_ioctl+0x33a/0x4c0

 [<ffffffff812d3d9c>] ? debug_object_deactivate+0x5c/0x110

 [<ffffffff812d333c>] ? do_raw_spin_unlock+0x6c/0xc0

 [<ffffffff8108280d>] ? trace_hardirqs_off+0xd/0x10

 [<ffffffff81644d03>] ? _raw_spin_unlock_irqrestore+0x53/0xa0

 [<ffffffff812d3deb>] ? debug_object_deactivate+0xab/0x110

 [<ffffffff81072ffc>] ? lock_hrtimer_base+0x2c/0x60

 [<ffffffff8112eff8>] vfs_ioctl+0x38/0xd0

 [<ffffffff8112f1ca>] do_vfs_ioctl+0x8a/0x5b0

 [<ffffffff81058dbc>] ? do_setitimer+0x1cc/0x1f0

 [<ffffffff810e8d72>] ? might_fault+0x72/0xd0

 [<ffffffff8112f73a>] sys_ioctl+0x4a/0x80

 [<ffffffff812d3d9c>] ? debug_object_deactivate+0x5c/0x110

 [<ffffffff81003182>] system_call_fastpath+0x16/0x1b