Bug 9532

Created attachment 13943 [details]
Kernel config

After this I cannot seem to connect the USB keyboard again. Nothing happens when I connect it.

Reply-To: akpm@linux-foundation.org

On Mon, 10 Dec 2007 05:30:36 -0800 (PST)
bugme-daemon@bugzilla.kernel.org wrote:

> http://bugzilla.kernel.org/show_bug.cgi?id=9532
> 
>            Summary: circular locking dependency when unplugging USB keyboard
>            Product: Drivers
>            Version: 2.5
>      KernelVersion: 2.6.24-rc4
>           Platform: All
>         OS/Version: Linux
>               Tree: Mainline
>             Status: NEW
>           Severity: normal
>           Priority: P1
>          Component: USB
>         AssignedTo: greg@kroah.com
>         ReportedBy: marcus@better.se
> 
> 
> Most recent kernel where this bug did not occur: unknown
> Distribution: Debian
> Hardware Environment: i386 laptop (LG LE50 Express)
> Software Environment: Debian testing/unstable, X.org, KDE
> Problem Description:
> 
> I got the following messages when unplugging a USB-connected wireless
> keyboard.

Appears to be a regression.  The device was dead after this.

Here's the cleaned up lockdep trace (removed the pestiferous word-wrapping):


Dec 10 14:21:41 better kernel: usb 1-1: USB disconnect, address 3
Dec 10 14:21:41 better kernel: 
Dec 10 14:21:41 better kernel: =======================================================
Dec 10 14:21:41 better kernel: [ INFO: possible circular locking dependency
detected ]
Dec 10 14:21:41 better kernel: 2.6.24-rc4-lg #1
Dec 10 14:21:41 better kernel: -------------------------------------------------------
Dec 10 14:21:41 better kernel: khubd/680 is trying to acquire lock:
Dec 10 14:21:41 better kernel:  (&dev->pm_mutex){--..}, at: [<f8d0984b>]
usb_autopm_do_device+0x2b/0x110 [usbcore]
Dec 10 14:21:41 better kernel: 
Dec 10 14:21:41 better kernel: but task is already holding lock:
Dec 10 14:21:41 better kernel:  (&dev->pm_mutex/1){--..}, at: [<f8d034b1>]
usb_disconnect+0xf1/0x140 [usbcore]
Dec 10 14:21:41 better kernel: 
Dec 10 14:21:41 better kernel: which lock already depends on the new lock.
Dec 10 14:21:41 better kernel: 
Dec 10 14:21:41 better kernel: 
Dec 10 14:21:41 better kernel: the existing dependency chain (in reverse order)
is:
Dec 10 14:21:41 better kernel: 
Dec 10 14:21:41 better kernel: -> #6 (&dev->pm_mutex/1){--..}:
Dec 10 14:21:41 better kernel:        [<c0240980>] __lock_acquire+0xbc0/0x1080
Dec 10 14:21:41 better kernel:        [<f8d09eca>] usb_autopm_do_interface+0x3a/0xd0 [usbcore]
Dec 10 14:21:41 better kernel:        [<f8d09eca>] usb_autopm_do_interface+0x3a/0xd0 [usbcore]
Dec 10 14:21:41 better kernel:        [<c0240e9f>] lock_acquire+0x5f/0x80
Dec 10 14:21:41 better kernel:        [<f8d09eca>] usb_autopm_do_interface+0x3a/0xd0 [usbcore]
Dec 10 14:21:41 better kernel:        [<c043fcdf>] mutex_lock_nested+0x7f/0x2f0
Dec 10 14:21:41 better kernel:        [<f8d09eca>] usb_autopm_do_interface+0x3a/0xd0 [usbcore]
Dec 10 14:21:41 better kernel:        [<c03b5136>] input_open_device+0x26/0xa0
Dec 10 14:21:41 better kernel:        [<f8d09eca>] usb_autopm_do_interface+0x3a/0xd0 [usbcore]
Dec 10 14:21:41 better kernel:        [<f8d63a5b>] usbhid_open+0x3b/0x50
[usbhid]
Dec 10 14:21:41 better kernel:        [<f8d5eaaa>] hidinput_open+0xa/0x10 [hid]
Dec 10 14:21:41 better kernel:        [<c03b518a>] input_open_device+0x7a/0xa0
Dec 10 14:21:41 better kernel:        [<c037c56a>] kbd_connect+0x6a/0x90
Dec 10 14:21:41 better kernel:        [<c03b4d27>] input_attach_handler+0x57/0x90
Dec 10 14:21:41 better kernel:        [<c03b6f29>] input_register_device+0x1a9/0x210
Dec 10 14:21:41 better kernel:        [<f8d5b992>] hidinput_connect+0x382/0x32d0 [hid]
Dec 10 14:21:41 better kernel:        [<f8d64573>] hid_probe+0x933/0xce0
[usbhid]
Dec 10 14:21:41 better kernel:        [<c023f86f>] trace_hardirqs_on+0xaf/0x160
Dec 10 14:21:41 better kernel:        [<c043fb75>] __mutex_unlock_slowpath+0xb5/0x190
Dec 10 14:21:41 better kernel:        [<c023f86f>] trace_hardirqs_on+0xaf/0x160
Dec 10 14:21:41 better kernel:        [<f8d098a4>] usb_autopm_do_device+0x84/0x110 [usbcore]
Dec 10 14:21:41 better kernel:        [<f8d09407>] usb_match_one_id+0x27/0xb0
[usbcore]
Dec 10 14:21:41 better kernel:        [<f8d0a6b9>] usb_probe_interface+0xb9/0x140 [usbcore]
Dec 10 14:21:41 better kernel:        [<c0394c27>] driver_probe_device+0x87/0x190
Dec 10 14:21:41 better kernel:        [<c0394eb4>] __driver_attach+0xb4/0xc0
Dec 10 14:21:41 better kernel:        [<c0393fdc>] bus_for_each_dev+0x3c/0x60
Dec 10 14:21:41 better kernel:        [<c0394a96>] driver_attach+0x16/0x20
Dec 10 14:21:41 better kernel:        [<c0394e00>] __driver_attach+0x0/0xc0
Dec 10 14:21:41 better kernel:        [<c039437b>] bus_add_driver+0x8b/0x1f0
Dec 10 14:21:41 better kernel:        [<f8d0a1c9>] usb_register_driver+0x99/0x120 [usbcore]
Dec 10 14:21:41 better kernel:        [<f8877034>] 0xf8877034
Dec 10 14:21:41 better kernel:        [<c0237897>] blocking_notifier_call_chain+0x17/0x20
Dec 10 14:21:41 better kernel:        [<c0246dcd>] sys_init_module+0x12d/0x17d0
Dec 10 14:21:41 better kernel:        [<c02043a6>] syscall_call+0x7/0xb
Dec 10 14:21:41 better kernel:        [<ffffffff>] 0xffffffff
Dec 10 14:21:41 better kernel: 
Dec 10 14:21:41 better kernel: -> #5 (&dev->mutex){--..}:
Dec 10 14:21:41 better kernel:        [<c0240980>] __lock_acquire+0xbc0/0x1080
Dec 10 14:21:41 better kernel:        [<c03b509a>] input_register_handle+0x2a/0xa0
Dec 10 14:21:41 better kernel:        [<c0240e9f>] lock_acquire+0x5f/0x80
Dec 10 14:21:41 better kernel:        [<c03b509a>] input_register_handle+0x2a/0xa0
Dec 10 14:21:41 better kernel:        [<c043f7cb>] mutex_lock_interruptible_nested+0x8b/0x380
Dec 10 14:21:41 better kernel:        [<c03b509a>] input_register_handle+0x2a/0xa0
Dec 10 14:21:41 better kernel:        [<c023f6d8>] mark_held_locks+0x38/0x70
Dec 10 14:21:41 better kernel:        [<c03b509a>] input_register_handle+0x2a/0xa0
Dec 10 14:21:41 better kernel:        [<c03b509a>] input_register_handle+0x2a/0xa0
Dec 10 14:21:41 better kernel:        [<c037c54f>] kbd_connect+0x4f/0x90
Dec 10 14:21:41 better kernel:        [<c03b4d27>] input_attach_handler+0x57/0x90
Dec 10 14:21:41 better kernel:        [<c03b6f29>] input_register_device+0x1a9/0x210
Dec 10 14:21:41 better kernel:        [<c03b8cc6>] atkbd_connect+0x206/0x230
Dec 10 14:21:41 better kernel:        [<c03b1c68>] serio_connect_driver+0x28/0x50
Dec 10 14:21:41 better kernel:        [<c0394c27>] driver_probe_device+0x87/0x190
Dec 10 14:21:41 better kernel:        [<c0394eb4>] __driver_attach+0xb4/0xc0
Dec 10 14:21:41 better kernel:        [<c0393fdc>] bus_for_each_dev+0x3c/0x60
Dec 10 14:21:41 better kernel:        [<c0394a96>] driver_attach+0x16/0x20
Dec 10 14:21:41 better kernel:        [<c0394e00>] __driver_attach+0x0/0xc0
Dec 10 14:21:41 better kernel:        [<c03b29a6>] serio_thread+0x256/0x360
Dec 10 14:21:41 better kernel:        [<c021b280>] finish_task_switch+0x0/0xb0
Dec 10 14:21:41 better kernel:        [<c0233070>] autoremove_wake_function+0x0/0x40
Dec 10 14:21:41 better kernel:        [<c03b2750>] serio_thread+0x0/0x360
Dec 10 14:21:41 better kernel:        [<c0232dd2>] kthread+0x42/0x70
Dec 10 14:21:41 better kernel:        [<c0232d90>] kthread+0x0/0x70
Dec 10 14:21:41 better kernel:        [<c0204f5b>] kernel_thread_helper+0x7/0x1c
Dec 10 14:21:41 better kernel:        [<ffffffff>] 0xffffffff
Dec 10 14:21:41 better kernel: 
Dec 10 14:21:41 better kernel: -> #4 (input_mutex){--..}:
Dec 10 14:21:41 better kernel:        [<c0240980>] __lock_acquire+0xbc0/0x1080
Dec 10 14:21:41 better kernel:        [<c03b6ed4>] input_register_device+0x154/0x210
Dec 10 14:21:41 better kernel:        [<c021b280>] finish_task_switch+0x0/0xb0
Dec 10 14:21:41 better kernel:        [<c0240e9f>] lock_acquire+0x5f/0x80
Dec 10 14:21:41 better kernel:        [<c03b6ed4>] input_register_device+0x154/0x210
Dec 10 14:21:41 better kernel:        [<c043f7cb>] mutex_lock_interruptible_nested+0x8b/0x380
Dec 10 14:21:41 better kernel:        [<c03b6ed4>] input_register_device+0x154/0x210
Dec 10 14:21:41 better last message repeated 2 times
Dec 10 14:21:41 better kernel:        [<f8e6dda8>] rt2x00rfkill_register+0x78/0xd0 [rt2x00lib]
Dec 10 14:21:41 better kernel:        [<f8e6bb9f>] rt2x00lib_initialize+0x13f/0x160 [rt2x00lib]
Dec 10 14:21:41 better kernel:        [<f8e6c68a>] rt2x00mac_start+0x3a/0x70
[rt2x00lib]
Dec 10 14:21:41 better kernel:        [<f8ef0b77>] ieee80211_open+0x1e7/0x4a0
[mac80211]
Dec 10 14:21:41 better kernel:        [<c023f6d8>] mark_held_locks+0x38/0x70
Dec 10 14:21:41 better kernel:        [<c0224986>] local_bh_enable_ip+0x86/0x110
Dec 10 14:21:41 better kernel:        [<c03cde19>] dev_set_rx_mode+0x19/0x50
Dec 10 14:21:41 better kernel:        [<c03d04dc>] dev_open+0x4c/0x80
Dec 10 14:21:41 better kernel:        [<c03cef52>] dev_change_flags+0x82/0x1b0
Dec 10 14:21:41 better kernel:        [<c03cd3e2>] __dev_get_by_name+0x72/0x90
Dec 10 14:21:41 better kernel:        [<c04176f0>] devinet_ioctl+0x500/0x6a0
Dec 10 14:21:41 better kernel:        [<c03d0330>] dev_ioctl+0x480/0x560
Dec 10 14:21:41 better kernel:        [<c03c1942>] sock_ioctl+0xd2/0x230
Dec 10 14:21:41 better kernel:        [<c03c1870>] sock_ioctl+0x0/0x230
Dec 10 14:21:41 better kernel:        [<c028ac3b>] do_ioctl+0x2b/0x90
Dec 10 14:21:41 better kernel:        [<c028aea1>] vfs_ioctl+0x201/0x2d0
Dec 10 14:21:41 better kernel:        [<c023f86f>] trace_hardirqs_on+0xaf/0x160
Dec 10 14:21:41 better kernel:        [<c028afc6>] sys_ioctl+0x56/0x70
Dec 10 14:21:41 better kernel:        [<c020431e>] sysenter_past_esp+0x5f/0xa5
Dec 10 14:21:41 better kernel:        [<ffffffff>] 0xffffffff
Dec 10 14:21:41 better kernel: 
Dec 10 14:21:41 better kernel: -> #3 (rtnl_mutex){--..}:
Dec 10 14:21:41 better kernel:        [<c0240980>] __lock_acquire+0xbc0/0x1080
Dec 10 14:21:41 better kernel:        [<c03da345>] linkwatch_event+0x5/0x30
Dec 10 14:21:41 better kernel:        [<c020ae7f>] save_stack_trace+0x1f/0x40
Dec 10 14:21:41 better kernel:        [<c03da345>] linkwatch_event+0x5/0x30
Dec 10 14:21:41 better kernel:        [<c0240e9f>] lock_acquire+0x5f/0x80
Dec 10 14:21:41 better kernel:        [<c03da345>] linkwatch_event+0x5/0x30
Dec 10 14:21:41 better kernel:        [<c043fcdf>] mutex_lock_nested+0x7f/0x2f0
Dec 10 14:21:41 better kernel:        [<c03da345>] linkwatch_event+0x5/0x30
Dec 10 14:21:41 better kernel:        [<c03da340>] linkwatch_event+0x0/0x30
Dec 10 14:21:41 better kernel:        [<c03da345>] linkwatch_event+0x5/0x30
Dec 10 14:21:41 better kernel:        [<c022f43b>] run_workqueue+0x15b/0x1e0
Dec 10 14:21:41 better kernel:        [<c022f3e4>] run_workqueue+0x104/0x1e0
Dec 10 14:21:41 better kernel:        [<c022fe82>] worker_thread+0x82/0xe0
Dec 10 14:21:41 better kernel:        [<c0233070>] autoremove_wake_function+0x0/0x40
Dec 10 14:21:41 better kernel:        [<c022fe00>] worker_thread+0x0/0xe0
Dec 10 14:21:41 better kernel:        [<c0232dd2>] kthread+0x42/0x70
Dec 10 14:21:41 better kernel:        [<c0232d90>] kthread+0x0/0x70
Dec 10 14:21:41 better kernel:        [<c0204f5b>] kernel_thread_helper+0x7/0x1c
Dec 10 14:21:41 better kernel:        [<ffffffff>] 0xffffffff
Dec 10 14:21:41 better kernel: 
Dec 10 14:21:41 better kernel: -> #2 ((linkwatch_work).work){--..}:
Dec 10 14:21:41 better kernel:        [<c0240980>] __lock_acquire+0xbc0/0x1080
Dec 10 14:21:41 better kernel:        [<c022f3e4>] run_workqueue+0x104/0x1e0
Dec 10 14:21:41 better kernel:        [<c03da340>] linkwatch_event+0x0/0x30
Dec 10 14:21:41 better kernel:        [<c0240e9f>] lock_acquire+0x5f/0x80
Dec 10 14:21:41 better kernel:        [<c022f3e4>] run_workqueue+0x104/0x1e0
Dec 10 14:21:41 better kernel:        [<c022f437>] run_workqueue+0x157/0x1e0
Dec 10 14:21:41 better kernel:        [<c022f3e4>] run_workqueue+0x104/0x1e0
Dec 10 14:21:41 better kernel:        [<c022fe82>] worker_thread+0x82/0xe0
Dec 10 14:21:41 better kernel:        [<c0233070>] autoremove_wake_function+0x0/0x40
Dec 10 14:21:41 better kernel:        [<c022fe00>] worker_thread+0x0/0xe0
Dec 10 14:21:41 better kernel:        [<c0232dd2>] kthread+0x42/0x70
Dec 10 14:21:41 better kernel:        [<c0232d90>] kthread+0x0/0x70
Dec 10 14:21:41 better kernel:        [<c0204f5b>] kernel_thread_helper+0x7/0x1c
Dec 10 14:21:41 better kernel:        [<ffffffff>] 0xffffffff
Dec 10 14:21:41 better kernel: 
Dec 10 14:21:41 better kernel: -> #1 (events){--..}:
Dec 10 14:21:41 better kernel:        [<c0240980>] __lock_acquire+0xbc0/0x1080
Dec 10 14:21:41 better kernel:        [<c022fa80>] flush_workqueue+0x0/0x70
Dec 10 14:21:41 better kernel:        [<c043fdec>] mutex_lock_nested+0x18c/0x2f0
Dec 10 14:21:41 better kernel:        [<c023f86f>] trace_hardirqs_on+0xaf/0x160
Dec 10 14:21:41 better kernel:        [<c0240e9f>] lock_acquire+0x5f/0x80
Dec 10 14:21:41 better kernel:        [<c022fa80>] flush_workqueue+0x0/0x70
Dec 10 14:21:41 better kernel:        [<c022fac3>] flush_workqueue+0x43/0x70
Dec 10 14:21:41 better kernel:        [<c022fa80>] flush_workqueue+0x0/0x70
Dec 10 14:21:41 better kernel:        [<f8d04338>] hub_suspend+0x48/0x50
[usbcore]
Dec 10 14:21:41 better kernel:        [<f8d04340>] hub_resume+0x0/0x10
[usbcore]
Dec 10 14:21:41 better kernel:        [<f8d09c18>] usb_suspend_both+0xc8/0x2f0
[usbcore]
Dec 10 14:21:41 better kernel:        [<f8d0984b>] usb_autopm_do_device+0x2b/0x110 [usbcore]
Dec 10 14:21:41 better kernel:        [<f8d098e4>] usb_autopm_do_device+0xc4/0x110 [usbcore]
Dec 10 14:21:41 better kernel:        [<f8d09f70>] usb_autosuspend_work+0x0/0x10 [usbcore]
Dec 10 14:21:41 better kernel:        [<f8d09f70>] usb_autosuspend_work+0x0/0x10 [usbcore]
Dec 10 14:21:41 better kernel:        [<c022f43b>] run_workqueue+0x15b/0x1e0
Dec 10 14:21:41 better kernel:        [<c022f3e4>] run_workqueue+0x104/0x1e0
Dec 10 14:21:41 better kernel:        [<c022fe82>] worker_thread+0x82/0xe0
Dec 10 14:21:41 better kernel:        [<c0233070>] autoremove_wake_function+0x0/0x40
Dec 10 14:21:41 better kernel:        [<c022fe00>] worker_thread+0x0/0xe0
Dec 10 14:21:41 better kernel:        [<c0232dd2>] kthread+0x42/0x70
Dec 10 14:21:41 better kernel:        [<c0232d90>] kthread+0x0/0x70
Dec 10 14:21:41 better kernel:        [<c0204f5b>] kernel_thread_helper+0x7/0x1c
Dec 10 14:21:41 better kernel:        [<ffffffff>] 0xffffffff
Dec 10 14:21:41 better kernel: 
Dec 10 14:21:41 better kernel: -> #0 (&dev->pm_mutex){--..}:
Dec 10 14:21:41 better kernel:        [<c02407ab>] __lock_acquire+0x9eb/0x1080
Dec 10 14:21:41 better kernel:        [<f8d0984b>] usb_autopm_do_device+0x2b/0x110 [usbcore]
Dec 10 14:21:41 better kernel:        [<c0240e9f>] lock_acquire+0x5f/0x80
Dec 10 14:21:41 better kernel:        [<f8d0984b>] usb_autopm_do_device+0x2b/0x110 [usbcore]
Dec 10 14:21:41 better kernel:        [<c043fcdf>] mutex_lock_nested+0x7f/0x2f0
Dec 10 14:21:41 better kernel:        [<f8d0984b>] usb_autopm_do_device+0x2b/0x110 [usbcore]
Dec 10 14:21:41 better kernel:        [<f8d0984b>] usb_autopm_do_device+0x2b/0x110 [usbcore]
Dec 10 14:21:41 better kernel:        [<f8d034ee>] usb_disconnect+0x12e/0x140
[usbcore]
Dec 10 14:21:41 better kernel:        [<f8d049d0>] hub_thread+0x460/0xcb0
[usbcore]
Dec 10 14:21:41 better kernel:        [<c04413bb>] _spin_unlock_irq+0x2b/0x50
Dec 10 14:21:41 better kernel:        [<c021b2db>] finish_task_switch+0x5b/0xb0
Dec 10 14:21:41 better kernel:        [<c0233070>] autoremove_wake_function+0x0/0x40
Dec 10 14:21:41 better kernel:        [<f8d04570>] hub_thread+0x0/0xcb0
[usbcore]
Dec 10 14:21:41 better kernel:        [<c0232dd2>] kthread+0x42/0x70
Dec 10 14:21:41 better kernel:        [<c0232d90>] kthread+0x0/0x70
Dec 10 14:21:41 better kernel:        [<c0204f5b>] kernel_thread_helper+0x7/0x1c
Dec 10 14:21:41 better kernel:        [<ffffffff>] 0xffffffff
Dec 10 14:21:41 better kernel: 
Dec 10 14:21:41 better kernel: other info that might help us debug this:
Dec 10 14:21:41 better kernel: 
Dec 10 14:21:41 better kernel: 1 lock held by khubd/680:
Dec 10 14:21:41 better kernel:  #0:  (&dev->pm_mutex/1){--..}, at: [<f8d034b1>] usb_disconnect+0xf1/0x140 [usbcore]
Dec 10 14:21:41 better kernel: 
Dec 10 14:21:41 better kernel: stack backtrace:
Dec 10 14:21:41 better kernel: Pid: 680, comm: khubd Not tainted 2.6.24-rc4-lg
#1
Dec 10 14:21:41 better kernel:  [<c023eb4a>] print_circular_bug_tail+0x7a/0x90
Dec 10 14:21:41 better kernel:  [<c02407ab>] __lock_acquire+0x9eb/0x1080
Dec 10 14:21:41 better kernel:  [<f8d0984b>] usb_autopm_do_device+0x2b/0x110 [usbcore]
Dec 10 14:21:41 better kernel:  [<c0240e9f>] lock_acquire+0x5f/0x80
Dec 10 14:21:41 better kernel:  [<f8d0984b>] usb_autopm_do_device+0x2b/0x110 [usbcore]
Dec 10 14:21:41 better kernel:  [<c043fcdf>] mutex_lock_nested+0x7f/0x2f0
Dec 10 14:21:41 better kernel:  [<f8d0984b>] usb_autopm_do_device+0x2b/0x110 [usbcore]
Dec 10 14:21:41 better kernel:  [<f8d0984b>] usb_autopm_do_device+0x2b/0x110 [usbcore]
Dec 10 14:21:41 better kernel:  [<f8d034ee>] usb_disconnect+0x12e/0x140 [usbcore]
Dec 10 14:21:41 better kernel:  [<f8d049d0>] hub_thread+0x460/0xcb0 [usbcore]
Dec 10 14:21:41 better kernel:  [<c04413bb>] _spin_unlock_irq+0x2b/0x50
Dec 10 14:21:41 better kernel:  [<c021b2db>] finish_task_switch+0x5b/0xb0
Dec 10 14:21:41 better kernel:  [<c0233070>] autoremove_wake_function+0x0/0x40
Dec 10 14:21:41 better kernel:  [<f8d04570>] hub_thread+0x0/0xcb0 [usbcore]
Dec 10 14:21:41 better kernel:  [<c0232dd2>] kthread+0x42/0x70
Dec 10 14:21:41 better kernel:  [<c0232d90>] kthread+0x0/0x70
Dec 10 14:21:41 better kernel:  [<c0204f5b>] kernel_thread_helper+0x7/0x1c
Dec 10 14:21:41 better kernel:  =======================

Andrew Morton skrev:
>> http://bugzilla.kernel.org/show_bug.cgi?id=9532
>>
>>            Summary: circular locking dependency when unplugging USB keyboard
>> I got the following messages when unplugging a USB-connected wireless
>> keyboard.
> 
> Appears to be a regression.  The device was dead after this.

Sorry, I have to try to confirm the deadness again tomorrow. It's 
possible that the keyboard needed some prodding (pressing some sort of 
reset button), although it usually just works.

Marcus

Created attachment 13955 [details]
Convert flush_scheduled_work to cancel_work_sync in hub.c

Does the problem occur repeatably?  If it does, you ought to be able to tell whether this patch helps.

> ------- Comment #5 from stern@rowland.harvard.edu  2007-12-10 13:45 -------
> Convert flush_scheduled_work to cancel_work_sync in hub.c
>
> Does the problem occur repeatably?

Yes, the problem is reproducible but only occurs the first time the keyboard 
is unplugged. If I repeatedly insert and unplug it, the message is not shown.

I also have to modify my previous report: the keyboard now works after 
plugging it in (even without the patch).

>  If it does, you ought to be able to tell whether this patch helps.

Yes, it eliminates the messages.

Cheers,

Marcus

The patch has been submitted.  You can close the bug whenever you want.

Fixed by:

commit d48bd977e0dd8c17081d12242bfc09d743ea0d26
Author: Alan Stern <stern@rowland.harvard.edu>
Date:   Tue Dec 11 16:02:23 2007 -0500

    USB: fix locking loop by avoiding flush_scheduled_work

http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d48bd977e0dd8c17081d12242bfc09d743ea0d26