INFO: task hung in chaoskey_disconnect

INFO: task hung in chaoskey_disconnect

[syzbot]

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


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this bug, for details see:
https://goo.gl/tpsmEJ#testing-patches

Re: INFO: task hung in chaoskey_disconnect

[Stephen Boyd]

Quoting syzbot (2019-11-06 04:32:09)
> 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

I suspect this is because of the kthread getting stuck problem reported
by Maciej. Maybe try the commit that Herbert picked up.

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6.git linus

Re: Re: INFO: task hung in chaoskey_disconnect

[syzbot]

> Quoting syzbot (2019-11-06 04:32:09)
>> 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

> I suspect this is because of the kthread getting stuck problem reported
> by Maciej. Maybe try the commit that Herbert picked up.

> #syz test:  
> git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6.git linus

Bugs found by USB fuzzer can only be tested on  
https://github.com/google/kasan.git tree,
usb-fuzzer branch because USB fuzzer is not upstreamed yet.
See https://goo.gl/tpsmEJ#usb-fuzzer for details.

Re: INFO: task hung in chaoskey_disconnect

[Stephen Boyd]

Quoting syzbot (2019-11-06 04:32:09)
> 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
> 

There are two reports. Let's test this one too.

#syz test: https://github.com/google/kasan.git b1aa9d83

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 5b799aa973a3..c487709499fc 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -2440,8 +2440,8 @@ void add_hwgenerator_randomness(const char *buffer, size_t count,
 	 * We'll be woken up again once below random_write_wakeup_thresh,
 	 * or when the calling thread is about to terminate.
 	 */
-	wait_event_freezable(random_write_wait,
-			kthread_should_stop() ||
+	wait_event_interruptible(random_write_wait,
+			kthread_should_stop() || freezing(current) ||
 			ENTROPY_BITS(&input_pool) <= random_write_wakeup_bits);
 	mix_pool_bytes(poolp, buffer, count);
 	credit_entropy_bits(poolp, entropy);

Re: INFO: task hung in chaoskey_disconnect

[syzbot]

Hello,

syzbot has tested the proposed patch but the reproducer still triggered  
crash:
KASAN: use-after-free Read in chaoskey_disconnect

usb 3-1: New USB device found, idVendor=1d50, idProduct=60c6,  
bcdDevice=1a.d7
usb 3-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
usb 3-1: config 0 descriptor??
usb 3-1: string descriptor 0 read error: -71
usb 3-1: USB disconnect, device number 14
==================================================================
BUG: KASAN: use-after-free in atomic_read  
include/asm-generic/atomic-instrumented.h:26 [inline]
BUG: KASAN: use-after-free in refcount_inc_not_zero_checked+0x72/0x1e0  
lib/refcount.c:123
Read of size 4 at addr ffff8881d91ec820 by task kworker/1:2/100

CPU: 1 PID: 100 Comm: kworker/1:2 Not tainted 5.4.0-rc6+ #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: usb_hub_wq hub_event
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0xca/0x13e lib/dump_stack.c:113
  print_address_description.constprop.0+0x36/0x50 mm/kasan/report.c:374
  __kasan_report.cold+0x1a/0x33 mm/kasan/report.c:506
  kasan_report+0xe/0x20 mm/kasan/common.c:634
  check_memory_region_inline mm/kasan/generic.c:185 [inline]
  check_memory_region+0x128/0x190 mm/kasan/generic.c:192
  atomic_read include/asm-generic/atomic-instrumented.h:26 [inline]
  refcount_inc_not_zero_checked+0x72/0x1e0 lib/refcount.c:123
  refcount_inc_checked+0x12/0x60 lib/refcount.c:156
  get_task_struct include/linux/sched/task.h:110 [inline]
  kthread_stop+0x6c/0x610 kernel/kthread.c:554
  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

Allocated by task 2:
  save_stack+0x1b/0x80 mm/kasan/common.c:69
  set_track mm/kasan/common.c:77 [inline]
  __kasan_kmalloc mm/kasan/common.c:510 [inline]
  __kasan_kmalloc.constprop.0+0xbf/0xd0 mm/kasan/common.c:483
  slab_post_alloc_hook mm/slab.h:584 [inline]
  slab_alloc_node mm/slub.c:2779 [inline]
  kmem_cache_alloc_node+0xdc/0x310 mm/slub.c:2815
  alloc_task_struct_node kernel/fork.c:169 [inline]
  dup_task_struct kernel/fork.c:865 [inline]
  copy_process+0x4201/0x6470 kernel/fork.c:1851
  _do_fork+0x129/0xec0 kernel/fork.c:2366
  kernel_thread+0xaa/0xe0 kernel/fork.c:2453
  create_kthread kernel/kthread.c:278 [inline]
  kthreadd+0x4a2/0x680 kernel/kthread.c:596
  ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Freed by task 0:
  save_stack+0x1b/0x80 mm/kasan/common.c:69
  set_track mm/kasan/common.c:77 [inline]
  kasan_set_free_info mm/kasan/common.c:332 [inline]
  __kasan_slab_free+0x130/0x180 mm/kasan/common.c:471
  slab_free_hook mm/slub.c:1424 [inline]
  slab_free_freelist_hook mm/slub.c:1475 [inline]
  slab_free mm/slub.c:3025 [inline]
  kmem_cache_free+0xb9/0x380 mm/slub.c:3041
  __put_task_struct+0x1e2/0x4c0 kernel/fork.c:748
  put_task_struct include/linux/sched/task.h:119 [inline]
  delayed_put_task_struct+0x1b4/0x2c0 kernel/exit.c:182
  __rcu_reclaim kernel/rcu/rcu.h:222 [inline]
  rcu_do_batch kernel/rcu/tree.c:2157 [inline]
  rcu_core+0x630/0x1ca0 kernel/rcu/tree.c:2377
  __do_softirq+0x221/0x912 kernel/softirq.c:292

The buggy address belongs to the object at ffff8881d91ec800
  which belongs to the cache task_struct of size 5888
The buggy address is located 32 bytes inside of
  5888-byte region [ffff8881d91ec800, ffff8881d91edf00)
The buggy address belongs to the page:
page:ffffea0007647a00 refcount:1 mapcount:0 mapping:ffff8881da116000  
index:0xffff8881d91e9800 compound_mapcount: 0
flags: 0x200000000010200(slab|head)
raw: 0200000000010200 0000000000000000 0000000100000001 ffff8881da116000
raw: ffff8881d91e9800 0000000080050003 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
  ffff8881d91ec700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
  ffff8881d91ec780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff8881d91ec800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                ^
  ffff8881d91ec880: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
  ffff8881d91ec900: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit:         b1aa9d83 usb: raw: add raw-gadget interface
git tree:       https://github.com/google/kasan.git
console output: https://syzkaller.appspot.com/x/log.txt?x=1498da1ce00000
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)
patch:          https://syzkaller.appspot.com/x/patch.diff?x=114dbc8ce00000

Re: INFO: task hung in chaoskey_disconnect

[Oliver Neukum]

Am Freitag, den 15.11.2019, 09:51 -0800 schrieb Stephen Boyd:
> Quoting syzbot (2019-11-06 04:32:09)
> > 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
> 
> I suspect this is because of the kthread getting stuck problem reported
> by Maciej. Maybe try the commit that Herbert picked up.

Do you have a commit ID so we can test an exported patch?

	Regards
		Oliver

Re: INFO: task hung in chaoskey_disconnect

[Stephen Boyd]

Quoting Oliver Neukum (2019-11-20 02:55:49)
> Am Freitag, den 15.11.2019, 09:51 -0800 schrieb Stephen Boyd:
> > Quoting syzbot (2019-11-06 04:32:09)
> > > 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
> > 
> > I suspect this is because of the kthread getting stuck problem reported
> > by Maciej. Maybe try the commit that Herbert picked up.
> 
> Do you have a commit ID so we can test an exported patch?
> 

I sent the patch in. See https://lkml.kernel.org/r/00000000000019acd8059770942b@google.com
for what happened. It didn't make a difference. I'll have to stare at it
a little more to figure out what's going on.

Re: INFO: task hung in chaoskey_disconnect

[Andrey Konovalov]

On Wed, Nov 6, 2019 at 1:32 PM syzbot
<syzbot+f41c4f7c6d8b0b778780@syzkaller.appspotmail.com> wrote:
>
> 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
>
>
> ---
> This bug is generated by a bot. It may contain errors.
> See https://goo.gl/tpsmEJ for more information about syzbot.
> syzbot engineers can be reached at syzkaller@googlegroups.com.
>
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> syzbot can test patches for this bug, for details see:
> https://goo.gl/tpsmEJ#testing-patches

Closing old USB bugs that haven't happened for a long time.

#syz invalid