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Date: Wed, 13 Jul 2011 11:18:45 -0400 (EDT)
From: Alan Stern <stern@rowland.harvard.edu>
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To: Thilo-Alexander Ginkel <thilo@ginkel.com>
cc: linux-kernel@vger.kernel.org, <linux-usb@vger.kernel.org>
Subject: Re: task khubd:25 blocked for more than 120 seconds (potential
 3.0-rc4 regression)
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On Wed, 13 Jul 2011, Thilo-Alexander Ginkel wrote:

> Hi there,
> 
> the following dmesg output just caught my attention:
> 
> [ 7306.160699] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs"
> disables this message.
> [ 7306.160705] khubd           D ffff88021103c890     0    25      2 0x00000000
> [ 7306.160716]  ffff88021110dae0 0000000000000046 ffffffff815e2844
> ffff88021110dfd8
> [ 7306.160725]  ffff88021110dae0 0000000000012a40 0000000000012a40
> ffff88021110dfd8
> [ 7306.160734]  ffff88021110dfd8 0000000000012a40 ffff88021103c4d0
> ffff8801a81cdbc0
> [ 7306.160743] Call Trace:
> [ 7306.160758]  [<ffffffff815e2844>] ? _raw_spin_lock_irqsave+0x34/0x50
> [ 7306.160802]  [<ffffffff81034f69>] ? default_spin_lock_flags+0x9/0x10
> [ 7306.160810]  [<ffffffff815e2844>] ? _raw_spin_lock_irqsave+0x34/0x50
> [ 7306.160820]  [<ffffffff815eb80e>] ? apic_timer_interrupt+0xe/0x20
> [ 7306.160829]  [<ffffffff81448337>] ? hub_release+0x27/0x30
> [ 7306.160838]  [<ffffffff815e1609>] __mutex_lock_slowpath+0xd9/0x150
> [ 7306.160845]  [<ffffffff81448337>] ? hub_release+0x27/0x30
> [ 7306.160852]  [<ffffffff815e128b>] mutex_lock+0x2b/0x50
> [ 7306.160861]  [<ffffffff8145180b>] usb_set_interface+0x8b/0x280
> [ 7306.160872]  [<ffffffff8107e625>] ? __cancel_work_timer+0x45/0x80
> [ 7306.160881]  [<ffffffff814532a2>] usb_unbind_interface+0x122/0x170
> [ 7306.160890]  [<ffffffff813cdf6c>] __device_release_driver+0x7c/0xe0
> [ 7306.160896]  [<ffffffff813ce64d>] device_release_driver+0x2d/0x40
> [ 7306.160903]  [<ffffffff813cd984>] bus_remove_device+0x74/0xa0
> [ 7306.160912]  [<ffffffff813cb07f>] device_del+0x12f/0x1b0
> [ 7306.160920]  [<ffffffff81450146>] usb_disable_device+0x76/0x180
> [ 7306.160927]  [<ffffffff81448aac>] usb_disconnect+0x9c/0x120
> [ 7306.160935]  [<ffffffff8144a13d>] hub_port_connect_change+0x37d/0x680
> [ 7306.160943]  [<ffffffff81447255>] ? get_port_status+0x55/0xc0
> [ 7306.160950]  [<ffffffff81447754>] ? hub_port_status+0x74/0xc0
> [ 7306.160957]  [<ffffffff8144ad07>] hub_events+0x3e7/0x5b0
> [ 7306.160967]  [<ffffffff8108ce2d>] ? refrigerator+0xed/0x130
> [ 7306.160974]  [<ffffffff8144bb4d>] hub_thread+0x3d/0x160
> [ 7306.160982]  [<ffffffff81084630>] ? wake_up_bit+0x40/0x40
> [ 7306.160990]  [<ffffffff8144bb10>] ? usb_authorize_device+0x180/0x180
> [ 7306.160997]  [<ffffffff81083f67>] kthread+0x97/0xa0
> [ 7306.161006]  [<ffffffff815ebf64>] kernel_thread_helper+0x4/0x10
> [ 7306.161015]  [<ffffffff81083ed0>] ? kthread_bind+0x80/0x80
> [ 7306.161023]  [<ffffffff815ebf60>] ? gs_change+0x13/0x13
> 
> I do not remeber having seen it on 2.6.38, so it might be a regression
> in 3.0-rc4, which I am currently running.
> 
> Some further details: Lenovo T420s (Sandy Bridge Core i5), x86_64
> 
> Attempting to run a lsusb hangs at the moment, I'll supply its output
> later when I have had a chance to reboot.
> 
> Is there a way to figure out whether a specific device is causing the hang?

This has been fixed in 3.0-rc7.

Alan Stern