INFO: task hung in chaoskey_disconnect

syzbot
2019-11-06T12:32:19Z

Hello,

syzbot found the following crash on:

HEAD commit: b1aa9d83 usb: raw: add raw-gadget interface
git tree: https://github.com/google/kasan.git usb-fuzzer
console output: https://syzkaller.appspot.com/x/log.txt?x=16ae2adce00000
kernel config: https://syzkaller.appspot.com/x/.config?x=79de80330003b5f7
dashboard link: https://syzkaller.appspot.com/bug?extid=f41c4f7c6d8b0b778780
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10248158e00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=16afbf7ce00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+f41c4f7c6d8b0b778780@syzkaller.appspotmail.com

INFO: task kworker/0:2:101 blocked for more than 143 seconds.
Not tainted 5.4.0-rc6+ #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/0:2 D25552 101 2 0x80004000
Workqueue: usb_hub_wq hub_event
Call Trace:
schedule+0xca/0x250 kernel/sched/core.c:4136
schedule_timeout+0x682/0xb20 kernel/time/timer.c:1871
do_wait_for_common kernel/sched/completion.c:83 [inline]
__wait_for_common kernel/sched/completion.c:104 [inline]
wait_for_common kernel/sched/completion.c:115 [inline]
wait_for_completion+0x26f/0x3c0 kernel/sched/completion.c:136
kthread_stop+0x10c/0x610 kernel/kthread.c:559
hwrng_unregister+0x190/0x210 drivers/char/hw_random/core.c:538
chaoskey_disconnect+0x1b2/0x200 drivers/usb/misc/chaoskey.c:232
usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
__device_release_driver drivers/base/dd.c:1134 [inline]
device_release_driver_internal+0x42f/0x500 drivers/base/dd.c:1165
bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:532
device_del+0x420/0xb20 drivers/base/core.c:2376
usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2200
hub_port_connect drivers/usb/core/hub.c:5035 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5324 [inline]
port_event drivers/usb/core/hub.c:5470 [inline]
hub_event+0x16f2/0x3800 drivers/usb/core/hub.c:5552
process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
process_scheduled_works kernel/workqueue.c:2331 [inline]
worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
INFO: task kworker/1:2:102 blocked for more than 143 seconds.
Not tainted 5.4.0-rc6+ #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/1:2 D25608 102 2 0x80004000
Workqueue: usb_hub_wq hub_event
Call Trace:
schedule+0xca/0x250 kernel/sched/core.c:4136
schedule_timeout+0x682/0xb20 kernel/time/timer.c:1871
do_wait_for_common kernel/sched/completion.c:83 [inline]
__wait_for_common kernel/sched/completion.c:104 [inline]
wait_for_common kernel/sched/completion.c:115 [inline]
wait_for_completion+0x26f/0x3c0 kernel/sched/completion.c:136
kthread_stop+0x10c/0x610 kernel/kthread.c:559
hwrng_unregister+0x190/0x210 drivers/char/hw_random/core.c:538
chaoskey_disconnect+0x1b2/0x200 drivers/usb/misc/chaoskey.c:232
usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
__device_release_driver drivers/base/dd.c:1134 [inline]
device_release_driver_internal+0x42f/0x500 drivers/base/dd.c:1165
bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:532
device_del+0x420/0xb20 drivers/base/core.c:2376
usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2200
hub_port_connect drivers/usb/core/hub.c:5035 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5324 [inline]
port_event drivers/usb/core/hub.c:5470 [inline]
hub_event+0x16f2/0x3800 drivers/usb/core/hub.c:5552
process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
process_scheduled_works kernel/workqueue.c:2331 [inline]
worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
INFO: task kworker/1:0:1732 blocked for more than 143 seconds.
Not tainted 5.4.0-rc6+ #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/1:0 D26016 1732 2 0x80004000
Workqueue: usb_hub_wq hub_event
Call Trace:
schedule+0xca/0x250 kernel/sched/core.c:4136
schedule_timeout+0x682/0xb20 kernel/time/timer.c:1871
do_wait_for_common kernel/sched/completion.c:83 [inline]
__wait_for_common kernel/sched/completion.c:104 [inline]
wait_for_common kernel/sched/completion.c:115 [inline]
wait_for_completion+0x26f/0x3c0 kernel/sched/completion.c:136
kthread_stop+0x10c/0x610 kernel/kthread.c:559
hwrng_unregister+0x190/0x210 drivers/char/hw_random/core.c:538
chaoskey_disconnect+0x1b2/0x200 drivers/usb/misc/chaoskey.c:232
usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
__device_release_driver drivers/base/dd.c:1134 [inline]
device_release_driver_internal+0x42f/0x500 drivers/base/dd.c:1165
bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:532
device_del+0x420/0xb20 drivers/base/core.c:2376
usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2200
hub_port_connect drivers/usb/core/hub.c:5035 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5324 [inline]
port_event drivers/usb/core/hub.c:5470 [inline]
hub_event+0x16f2/0x3800 drivers/usb/core/hub.c:5552
process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
process_scheduled_works kernel/workqueue.c:2331 [inline]
worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
INFO: task kworker/1:3:1733 blocked for more than 144 seconds.
Not tainted 5.4.0-rc6+ #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/1:3 D26016 1733 2 0x80004000
Workqueue: usb_hub_wq hub_event
Call Trace:
schedule+0xca/0x250 kernel/sched/core.c:4136
schedule_timeout+0x682/0xb20 kernel/time/timer.c:1871
do_wait_for_common kernel/sched/completion.c:83 [inline]
__wait_for_common kernel/sched/completion.c:104 [inline]
wait_for_common kernel/sched/completion.c:115 [inline]
wait_for_completion+0x26f/0x3c0 kernel/sched/completion.c:136
kthread_stop+0x10c/0x610 kernel/kthread.c:559
hwrng_unregister+0x190/0x210 drivers/char/hw_random/core.c:538
chaoskey_disconnect+0x1b2/0x200 drivers/usb/misc/chaoskey.c:232
usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
__device_release_driver drivers/base/dd.c:1134 [inline]
device_release_driver_internal+0x42f/0x500 drivers/base/dd.c:1165
bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:532
device_del+0x420/0xb20 drivers/base/core.c:2376
usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2200
hub_port_connect drivers/usb/core/hub.c:5035 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5324 [inline]
port_event drivers/usb/core/hub.c:5470 [inline]
hub_event+0x16f2/0x3800 drivers/usb/core/hub.c:5552
process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
process_scheduled_works kernel/workqueue.c:2331 [inline]
worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
INFO: task kworker/1:4:1735 blocked for more than 144 seconds.
Not tainted 5.4.0-rc6+ #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/1:4 D25760 1735 2 0x80004000
Workqueue: usb_hub_wq hub_event
Call Trace:
schedule+0xca/0x250 kernel/sched/core.c:4136
schedule_timeout+0x682/0xb20 kernel/time/timer.c:1871
do_wait_for_common kernel/sched/completion.c:83 [inline]
__wait_for_common kernel/sched/completion.c:104 [inline]
wait_for_common kernel/sched/completion.c:115 [inline]
wait_for_completion+0x26f/0x3c0 kernel/sched/completion.c:136
kthread_stop+0x10c/0x610 kernel/kthread.c:559
hwrng_unregister+0x190/0x210 drivers/char/hw_random/core.c:538
chaoskey_disconnect+0x1b2/0x200 drivers/usb/misc/chaoskey.c:232
usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423
__device_release_driver drivers/base/dd.c:1134 [inline]
device_release_driver_internal+0x42f/0x500 drivers/base/dd.c:1165
bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:532
device_del+0x420/0xb20 drivers/base/core.c:2376
usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237
usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2200
hub_port_connect drivers/usb/core/hub.c:5035 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5324 [inline]
port_event drivers/usb/core/hub.c:5470 [inline]
hub_event+0x16f2/0x3800 drivers/usb/core/hub.c:5552
process_one_work+0x92b/0x1530 kernel/workqueue.c:2269
process_scheduled_works kernel/workqueue.c:2331 [inline]
worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Showing all locks held in the system:
5 locks held by kworker/1:1/22:
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
__write_once_size include/linux/compiler.h:226 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at: atomic64_set
include/asm-generic/atomic-instrumented.h:855 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
atomic_long_set include/asm-generic/atomic-long.h:40 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at: set_work_data
kernel/workqueue.c:620 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
set_work_pool_and_clear_pending kernel/workqueue.c:647 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
process_one_work+0x827/0x1530 kernel/workqueue.c:2240
#1: ffff8881d932fdd0 ((work_completion)(&hub->events)){+.+.}, at:
process_one_work+0x85b/0x1530 kernel/workqueue.c:2244
#2: ffff8881d515c200 (&dev->mutex){....}, at: device_lock
include/linux/device.h:1462 [inline]
#2: ffff8881d515c200 (&dev->mutex){....}, at: hub_event+0x1b2/0x3800
drivers/usb/core/hub.c:5498
#3: ffff8881cb4fd200 (&dev->mutex){....}, at: device_lock
include/linux/device.h:1462 [inline]
#3: ffff8881cb4fd200 (&dev->mutex){....}, at: usb_disconnect+0x91/0x8d0
drivers/usb/core/hub.c:2191
#4: ffff8881cb4fe190 (&dev->mutex){....}, at:
device_release_driver_internal+0x23/0x500 drivers/base/dd.c:1162
1 lock held by khungtaskd/23:
#0: ffffffff86cfe8a0 (rcu_read_lock){....}, at:
debug_show_all_locks+0x53/0x269 kernel/locking/lockdep.c:5335
5 locks held by kworker/0:2/101:
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
__write_once_size include/linux/compiler.h:226 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at: atomic64_set
include/asm-generic/atomic-instrumented.h:855 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
atomic_long_set include/asm-generic/atomic-long.h:40 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at: set_work_data
kernel/workqueue.c:620 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
set_work_pool_and_clear_pending kernel/workqueue.c:647 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
process_one_work+0x827/0x1530 kernel/workqueue.c:2240
#1: ffff8881d536fdd0 ((work_completion)(&hub->events)){+.+.}, at:
process_one_work+0x85b/0x1530 kernel/workqueue.c:2244
#2: ffff8881d50a1200 (&dev->mutex){....}, at: device_lock
include/linux/device.h:1462 [inline]
#2: ffff8881d50a1200 (&dev->mutex){....}, at: hub_event+0x1b2/0x3800
drivers/usb/core/hub.c:5498
#3: ffff8881cffb7200 (&dev->mutex){....}, at: device_lock
include/linux/device.h:1462 [inline]
#3: ffff8881cffb7200 (&dev->mutex){....}, at: usb_disconnect+0x91/0x8d0
drivers/usb/core/hub.c:2191
#4: ffff8881cf220190 (&dev->mutex){....}, at:
device_release_driver_internal+0x23/0x500 drivers/base/dd.c:1162
5 locks held by kworker/1:2/102:
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
__write_once_size include/linux/compiler.h:226 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at: atomic64_set
include/asm-generic/atomic-instrumented.h:855 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
atomic_long_set include/asm-generic/atomic-long.h:40 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at: set_work_data
kernel/workqueue.c:620 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
set_work_pool_and_clear_pending kernel/workqueue.c:647 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
process_one_work+0x827/0x1530 kernel/workqueue.c:2240
#1: ffff8881d53d7dd0 ((work_completion)(&hub->events)){+.+.}, at:
process_one_work+0x85b/0x1530 kernel/workqueue.c:2244
#2: ffff8881d50d0200 (&dev->mutex){....}, at: device_lock
include/linux/device.h:1462 [inline]
#2: ffff8881d50d0200 (&dev->mutex){....}, at: hub_event+0x1b2/0x3800
drivers/usb/core/hub.c:5498
#3: ffff8881cea1b200 (&dev->mutex){....}, at: device_lock
include/linux/device.h:1462 [inline]
#3: ffff8881cea1b200 (&dev->mutex){....}, at: usb_disconnect+0x91/0x8d0
drivers/usb/core/hub.c:2191
#4: ffff8881cea1c190 (&dev->mutex){....}, at:
device_release_driver_internal+0x23/0x500 drivers/base/dd.c:1162
1 lock held by rsyslogd/1599:
#0: ffff8881d3aaad60 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xe3/0x100
fs/file.c:801
2 locks held by getty/1690:
#0: ffff8881d1458090 (&tty->ldisc_sem){++++}, at:
tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
#1: ffffc900004492e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x223/0x1ae0 drivers/tty/n_tty.c:2156
2 locks held by getty/1691:
#0: ffff8881d1569090 (&tty->ldisc_sem){++++}, at:
tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
#1: ffffc900004692e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x223/0x1ae0 drivers/tty/n_tty.c:2156
2 locks held by getty/1692:
#0: ffff8881d1430090 (&tty->ldisc_sem){++++}, at:
tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
#1: ffffc9000044d2e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x223/0x1ae0 drivers/tty/n_tty.c:2156
2 locks held by getty/1693:
#0: ffff8881d1436090 (&tty->ldisc_sem){++++}, at:
tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
#1: ffffc900004552e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x223/0x1ae0 drivers/tty/n_tty.c:2156
2 locks held by getty/1694:
#0: ffff8881d145e090 (&tty->ldisc_sem){++++}, at:
tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
#1: ffffc9000045d2e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x223/0x1ae0 drivers/tty/n_tty.c:2156
2 locks held by getty/1695:
#0: ffff8881d156a090 (&tty->ldisc_sem){++++}, at:
tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
#1: ffffc9000046d2e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x223/0x1ae0 drivers/tty/n_tty.c:2156
2 locks held by getty/1696:
#0: ffff8881d2225090 (&tty->ldisc_sem){++++}, at:
tty_ldisc_ref_wait+0x22/0x80 drivers/tty/tty_ldisc.c:272
#1: ffffc900004352e0 (&ldata->atomic_read_lock){+.+.}, at:
n_tty_read+0x223/0x1ae0 drivers/tty/n_tty.c:2156
5 locks held by kworker/1:0/1732:
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
__write_once_size include/linux/compiler.h:226 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at: atomic64_set
include/asm-generic/atomic-instrumented.h:855 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
atomic_long_set include/asm-generic/atomic-long.h:40 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at: set_work_data
kernel/workqueue.c:620 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
set_work_pool_and_clear_pending kernel/workqueue.c:647 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
process_one_work+0x827/0x1530 kernel/workqueue.c:2240
#1: ffff8881cfa67dd0 ((work_completion)(&hub->events)){+.+.}, at:
process_one_work+0x85b/0x1530 kernel/workqueue.c:2244
#2: ffff8881d512d200 (&dev->mutex){....}, at: device_lock
include/linux/device.h:1462 [inline]
#2: ffff8881d512d200 (&dev->mutex){....}, at: hub_event+0x1b2/0x3800
drivers/usb/core/hub.c:5498
#3: ffff8881cf153200 (&dev->mutex){....}, at: device_lock
include/linux/device.h:1462 [inline]
#3: ffff8881cf153200 (&dev->mutex){....}, at: usb_disconnect+0x91/0x8d0
drivers/usb/core/hub.c:2191
#4: ffff8881cf156190 (&dev->mutex){....}, at:
device_release_driver_internal+0x23/0x500 drivers/base/dd.c:1162
5 locks held by kworker/1:3/1733:
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
__write_once_size include/linux/compiler.h:226 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at: atomic64_set
include/asm-generic/atomic-instrumented.h:855 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
atomic_long_set include/asm-generic/atomic-long.h:40 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at: set_work_data
kernel/workqueue.c:620 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
set_work_pool_and_clear_pending kernel/workqueue.c:647 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
process_one_work+0x827/0x1530 kernel/workqueue.c:2240
#1: ffff8881d024fdd0 ((work_completion)(&hub->events)){+.+.}, at:
process_one_work+0x85b/0x1530 kernel/workqueue.c:2244
#2: ffff8881d50d7200 (&dev->mutex){....}, at: device_lock
include/linux/device.h:1462 [inline]
#2: ffff8881d50d7200 (&dev->mutex){....}, at: hub_event+0x1b2/0x3800
drivers/usb/core/hub.c:5498
#3: ffff8881c5fe9200 (&dev->mutex){....}, at: device_lock
include/linux/device.h:1462 [inline]
#3: ffff8881c5fe9200 (&dev->mutex){....}, at: usb_disconnect+0x91/0x8d0
drivers/usb/core/hub.c:2191
#4: ffff8881c5feb190 (&dev->mutex){....}, at:
device_release_driver_internal+0x23/0x500 drivers/base/dd.c:1162
5 locks held by kworker/1:4/1735:
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
__write_once_size include/linux/compiler.h:226 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at: atomic64_set
include/asm-generic/atomic-instrumented.h:855 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
atomic_long_set include/asm-generic/atomic-long.h:40 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at: set_work_data
kernel/workqueue.c:620 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
set_work_pool_and_clear_pending kernel/workqueue.c:647 [inline]
#0: ffff8881d8c82d28 ((wq_completion)usb_hub_wq){+.+.}, at:
process_one_work+0x827/0x1530 kernel/workqueue.c:2240
#1: ffff8881cfaa7dd0 ((work_completion)(&hub->events)){+.+.}, at:
process_one_work+0x85b/0x1530 kernel/workqueue.c:2244
#2: ffff8881d510e200 (&dev->mutex){....}, at: device_lock
include/linux/device.h:1462 [inline]
#2: ffff8881d510e200 (&dev->mutex){....}, at: hub_event+0x1b2/0x3800
drivers/usb/core/hub.c:5498
#3: ffff8881cf982200 (&dev->mutex){....}, at: device_lock
include/linux/device.h:1462 [inline]
#3: ffff8881cf982200 (&dev->mutex){....}, at: usb_disconnect+0x91/0x8d0
drivers/usb/core/hub.c:2191
#4: ffff8881cf400190 (&dev->mutex){....}, at:
device_release_driver_internal+0x23/0x500 drivers/base/dd.c:1162

=============================================

NMI backtrace for cpu 0
CPU: 0 PID: 23 Comm: khungtaskd Not tainted 5.4.0-rc6+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:77 [inline]
dump_stack+0xca/0x13e lib/dump_stack.c:113
nmi_cpu_backtrace.cold+0x55/0x96 lib/nmi_backtrace.c:101
nmi_trigger_cpumask_backtrace+0x1b0/0x1c7 lib/nmi_backtrace.c:62
trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline]
check_hung_uninterruptible_tasks kernel/hung_task.c:205 [inline]
watchdog+0x9a4/0xe50 kernel/hung_task.c:289
kthread+0x318/0x420 kernel/kthread.c:255
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352
Sending NMI from CPU 0 to CPUs 1:
NMI backtrace for cpu 1 skipped: idling at native_safe_halt
arch/x86/include/asm/irqflags.h:60 [inline]
NMI backtrace for cpu 1 skipped: idling at arch_safe_halt
arch/x86/include/asm/irqflags.h:103 [inline]
NMI backtrace for cpu 1 skipped: idling at default_idle+0x28/0x2e0
arch/x86/kernel/process.c:580

---
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