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I have an issue where on some boots my computer basically does not recognize anything plugged in to certain USB ports. Strangely, it never affects the USB hub built in to my monitor but usually it affects the ports that my keyboard and mouse are plugged into (so I end up having to plug them into my monitor). In dmesg I see information about udevd and khubd being hung like so:

[  599.539168] INFO: task khubd:35 blocked for more than 120 seconds.
[  599.539178] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  599.539184] khubd           D ffff8801afd93f40     0    35      2 0x00000000
[  599.539194]  ffff8801a6bc7bb8 0000000000000046 ffff8801a6bd1740 ffff8801a6bc7fd8
[  599.539204]  ffff8801a6bc7fd8 ffff8801a6bc7fd8 ffff8801a691c5c0 ffff8801a6bd1740
[  599.539212]  ffff8801a2885a80 0000000080000080 ffff8801a6bc7c18 ffff8801a6bc7c94
[  599.539220] Call Trace:
[  599.539237]  [<ffffffff816ca029>] schedule+0x29/0x70
[  599.539249]  [<ffffffff814fbde5>] usb_kill_urb+0x85/0xc0
[  599.539258]  [<ffffffff8107dc40>] ? finish_wait+0x80/0x80
[  599.539267]  [<ffffffff814fd058>] usb_start_wait_urb+0xd8/0xf0
[  599.539275]  [<ffffffff814fd2e0>] usb_control_msg+0xe0/0x140
[  599.539284]  [<ffffffff814f3f29>] hub_port_init+0x3a9/0xa50
[  599.539293]  [<ffffffff81044b49>] ? default_spin_lock_flags+0x9/0x10
[  599.539302]  [<ffffffff814f6b89>] hub_port_connect_change+0x249/0x9f0
[  599.539310]  [<ffffffff814f7575>] hub_events+0x245/0x700
[  599.539317]  [<ffffffff814f7a65>] hub_thread+0x35/0x1a0
[  599.539324]  [<ffffffff8107dc40>] ? finish_wait+0x80/0x80
[  599.539331]  [<ffffffff814f7a30>] ? hub_events+0x700/0x700
[  599.539337]  [<ffffffff8107d300>] kthread+0xc0/0xd0
[  599.539344]  [<ffffffff8107d240>] ? kthread_create_on_node+0x120/0x120
[  599.539353]  [<ffffffff816d372c>] ret_from_fork+0x7c/0xb0
[  599.539360]  [<ffffffff8107d240>] ? kthread_create_on_node+0x120/0x120

Sounds like maybe two threads are deadlocked?

Relevant Hardware: AMD Phenom II X4 925, Gigabyte GA-MA69G-S3H motherboard, Dell Ultrasharp monitor w/ hub.

Input devices: MS Ergonomic 4000, Logitech Trackball, Truly Ergonomic Keyboard, Logitech G400 (having two sets of input devices saves me a lot of time when this happens ;) )

Running ubuntu 13.04, full patched. Happened in 12.10 too but went away for a while.

Full dmesg output is at https://docs.google.com/file/d/0B9nvlyR1e8FNQW85RnZaSXJYQUU/edit?usp=sharing . Is this something that would make more sense as a bug report on launchpad?

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