bisecting fixing commit since cbfa1702aaf69b2311ea1b35e04f113c48368c67 building syzkaller on 1a3f94087169f62f9a5832828f62b4900e98b781 testing commit cbfa1702aaf69b2311ea1b35e04f113c48368c67 with gcc (GCC) 8.1.0 kernel signature: 6eb2036a9c82b15bcce79f24d82e0194e1948d20e2d3796a959a3620e8424b23 run #0: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #1: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #2: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #3: crashed: BUG: unable to handle kernel run #4: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #5: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #6: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #7: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #8: crashed: INFO: task hung in hub_port_init run #9: crashed: INFO: task hung in hub_port_init testing current HEAD 2762b48e9611529239da2e68cba908dbbec9805f testing commit 2762b48e9611529239da2e68cba908dbbec9805f with gcc (GCC) 8.1.0 kernel signature: 9189d90e90c4572a2e6bfec4ce5394db3aa73ed2270479ef20b6a01192caddf2 run #0: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #1: crashed: BUG: unable to handle kernel run #2: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #3: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #4: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #5: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #6: crashed: BUG: unable to handle kernel NULL pointer dereference in vhci_shutdown_connection run #7: crashed: INFO: task hung in hub_port_init run #8: crashed: INFO: task hung in hub_port_init run #9: crashed: INFO: task hung in hub_port_init revisions tested: 2, total time: 31m39.70906571s (build: 16m59.344256036s, test: 14m1.850296602s) the crash still happens on HEAD commit msg: Linux 4.14.216 crash: INFO: task hung in hub_port_init vhci_hcd: disconnect device vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 vhci_hcd: stop threads vhci_hcd: release socket INFO: task kworker/0:0:3 blocked for more than 140 seconds. vhci_hcd: disconnect device Not tainted 4.14.216-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/0:0 D26336 3 2 0x80000000 Workqueue: usb_hub_wq hub_event Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x824/0x1ee0 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 usb_kill_urb+0x193/0x210 drivers/usb/core/urb.c:691 usb_start_wait_urb+0x1fb/0x260 drivers/usb/core/message.c:62 usb_internal_control_msg drivers/usb/core/message.c:100 [inline] usb_control_msg+0x31b/0x550 drivers/usb/core/message.c:151 vhci_hcd vhci_hcd.0: port 1 already used vhci_hcd vhci_hcd.0: pdev(1) rhport(0) sockfd(3) hub_port_init+0x6a5/0x2640 drivers/usb/core/hub.c:4555 vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) hub_port_connect drivers/usb/core/hub.c:4905 [inline] hub_port_connect_change drivers/usb/core/hub.c:5088 [inline] port_event drivers/usb/core/hub.c:5194 [inline] hub_event+0x12fc/0x3230 drivers/usb/core/hub.c:5274 vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 process_one_work+0x74f/0x1620 kernel/workqueue.c:2116 vhci_hcd: stop threads vhci_hcd: release socket worker_thread+0xcc/0xed0 kernel/workqueue.c:2250 vhci_hcd: disconnect device kthread+0x338/0x400 kernel/kthread.c:232 vhci_hcd vhci_hcd.0: port 1 already used ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 INFO: task kworker/1:1:23 blocked for more than 140 seconds. Not tainted 4.14.216-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/1:1 D25712 23 2 0x80000000 vhci_hcd vhci_hcd.0: port 1 already used vhci_hcd vhci_hcd.0: pdev(4) rhport(0) sockfd(3) Workqueue: usb_hub_wq hub_event vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x824/0x1ee0 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 vhci_hcd vhci_hcd.0: pdev(3) rhport(0) sockfd(3) vhci_hcd: connection closed vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 usb_kill_urb+0x193/0x210 drivers/usb/core/urb.c:691 vhci_hcd: stop threads usb_start_wait_urb+0x1fb/0x260 drivers/usb/core/message.c:62 vhci_hcd: release socket usb_internal_control_msg drivers/usb/core/message.c:100 [inline] usb_control_msg+0x31b/0x550 drivers/usb/core/message.c:151 hub_port_init+0x6a5/0x2640 drivers/usb/core/hub.c:4555 vhci_hcd: disconnect device hub_port_connect drivers/usb/core/hub.c:4905 [inline] hub_port_connect_change drivers/usb/core/hub.c:5088 [inline] port_event drivers/usb/core/hub.c:5194 [inline] hub_event+0x12fc/0x3230 drivers/usb/core/hub.c:5274 vhci_hcd: stop threads process_one_work+0x74f/0x1620 kernel/workqueue.c:2116 vhci_hcd: release socket vhci_hcd vhci_hcd.0: port 1 already used vhci_hcd: disconnect device vhci_hcd vhci_hcd.0: pdev(5) rhport(0) sockfd(3) vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) worker_thread+0xcc/0xed0 kernel/workqueue.c:2250 vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 kthread+0x338/0x400 kernel/kthread.c:232 vhci_hcd: stop threads vhci_hcd: release socket vhci_hcd vhci_hcd.0: port 1 already used vhci_hcd: disconnect device ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 INFO: task kworker/0:2:3339 blocked for more than 140 seconds. Not tainted 4.14.216-syzkaller #0 vhci_hcd vhci_hcd.0: pdev(0) rhport(0) sockfd(3) "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) kworker/0:2 D25360 3339 2 0x80000000 vhci_hcd vhci_hcd.0: port 1 already used Workqueue: usb_hub_wq hub_event Call Trace: vhci_hcd vhci_hcd.0: pdev(2) rhport(0) sockfd(3) context_switch kernel/sched/core.c:2808 [inline] __schedule+0x824/0x1ee0 kernel/sched/core.c:3384 vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) vhci_hcd: connection closed vhci_hcd: stop threads vhci_hcd: release socket vhci_hcd: disconnect device schedule+0x7f/0x1b0 kernel/sched/core.c:3428 vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 usb_kill_urb+0x193/0x210 drivers/usb/core/urb.c:691 usb_start_wait_urb+0x1fb/0x260 drivers/usb/core/message.c:62 vhci_hcd: stop threads vhci_hcd: release socket usb_internal_control_msg drivers/usb/core/message.c:100 [inline] usb_control_msg+0x31b/0x550 drivers/usb/core/message.c:151 hub_port_init+0x6a5/0x2640 drivers/usb/core/hub.c:4555 hub_port_connect drivers/usb/core/hub.c:4905 [inline] hub_port_connect_change drivers/usb/core/hub.c:5088 [inline] port_event drivers/usb/core/hub.c:5194 [inline] hub_event+0x12fc/0x3230 drivers/usb/core/hub.c:5274 vhci_hcd: disconnect device vhci_hcd vhci_hcd.0: port 1 already used process_one_work+0x74f/0x1620 kernel/workqueue.c:2116 vhci_hcd vhci_hcd.0: pdev(1) rhport(0) sockfd(3) vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) worker_thread+0xcc/0xed0 kernel/workqueue.c:2250 vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 kthread+0x338/0x400 kernel/kthread.c:232 vhci_hcd: stop threads vhci_hcd: release socket vhci_hcd: disconnect device ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 INFO: task kworker/1:4:5864 blocked for more than 140 seconds. Not tainted 4.14.216-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/1:4 D24656 5864 2 0x80000000 Workqueue: usb_hub_wq hub_event Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x824/0x1ee0 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 usb_kill_urb+0x193/0x210 drivers/usb/core/urb.c:691 vhci_hcd vhci_hcd.0: port 1 already used vhci_hcd vhci_hcd.0: port 1 already used usb_start_wait_urb+0x1fb/0x260 drivers/usb/core/message.c:62 vhci_hcd vhci_hcd.0: pdev(3) rhport(0) sockfd(3) vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 vhci_hcd: stop threads usb_internal_control_msg drivers/usb/core/message.c:100 [inline] usb_control_msg+0x31b/0x550 drivers/usb/core/message.c:151 vhci_hcd: release socket hub_port_init+0x6a5/0x2640 drivers/usb/core/hub.c:4555 hub_port_connect drivers/usb/core/hub.c:4905 [inline] hub_port_connect_change drivers/usb/core/hub.c:5088 [inline] port_event drivers/usb/core/hub.c:5194 [inline] hub_event+0x12fc/0x3230 drivers/usb/core/hub.c:5274 vhci_hcd vhci_hcd.0: pdev(4) rhport(0) sockfd(3) process_one_work+0x74f/0x1620 kernel/workqueue.c:2116 vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) vhci_hcd vhci_hcd.0: port 1 already used worker_thread+0xcc/0xed0 kernel/workqueue.c:2250 vhci_hcd: disconnect device kthread+0x338/0x400 kernel/kthread.c:232 vhci_hcd: connection closed vhci_hcd: stop threads vhci_hcd: release socket ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 INFO: task kworker/0:5:7450 blocked for more than 140 seconds. vhci_hcd: disconnect device Not tainted 4.14.216-syzkaller #0 vhci_hcd vhci_hcd.0: pdev(5) rhport(0) sockfd(3) "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 kworker/0:5 D27896 7450 2 0x80000000 vhci_hcd: stop threads Workqueue: usb_hub_wq hub_event vhci_hcd vhci_hcd.0: port 1 already used Call Trace: vhci_hcd: release socket context_switch kernel/sched/core.c:2808 [inline] __schedule+0x824/0x1ee0 kernel/sched/core.c:3384 vhci_hcd: disconnect device schedule+0x7f/0x1b0 kernel/sched/core.c:3428 usb_kill_urb+0x193/0x210 drivers/usb/core/urb.c:691 vhci_hcd vhci_hcd.0: port 1 already used vhci_hcd vhci_hcd.0: pdev(0) rhport(0) sockfd(3) usb_start_wait_urb+0x1fb/0x260 drivers/usb/core/message.c:62 vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 vhci_hcd: stop threads vhci_hcd: release socket vhci_hcd vhci_hcd.0: pdev(2) rhport(0) sockfd(3) vhci_hcd: disconnect device vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 usb_internal_control_msg drivers/usb/core/message.c:100 [inline] usb_control_msg+0x31b/0x550 drivers/usb/core/message.c:151 vhci_hcd: stop threads vhci_hcd: release socket vhci_hcd: disconnect device hub_port_init+0x6a5/0x2640 drivers/usb/core/hub.c:4555 hub_port_connect drivers/usb/core/hub.c:4905 [inline] hub_port_connect_change drivers/usb/core/hub.c:5088 [inline] port_event drivers/usb/core/hub.c:5194 [inline] hub_event+0x12fc/0x3230 drivers/usb/core/hub.c:5274 process_one_work+0x74f/0x1620 kernel/workqueue.c:2116 vhci_hcd vhci_hcd.0: port 1 already used worker_thread+0xcc/0xed0 kernel/workqueue.c:2250 kthread+0x338/0x400 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 INFO: task kworker/0:6:7505 blocked for more than 140 seconds. vhci_hcd vhci_hcd.0: pdev(1) rhport(0) sockfd(3) Not tainted 4.14.216-syzkaller #0 vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 kworker/0:6 D26336 7505 2 0x80000000 vhci_hcd: stop threads Workqueue: usb_hub_wq hub_event vhci_hcd: release socket Call Trace: vhci_hcd: disconnect device context_switch kernel/sched/core.c:2808 [inline] __schedule+0x824/0x1ee0 kernel/sched/core.c:3384 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 usb_kill_urb+0x193/0x210 drivers/usb/core/urb.c:691 usb_start_wait_urb+0x1fb/0x260 drivers/usb/core/message.c:62 vhci_hcd vhci_hcd.0: port 1 already used usb_internal_control_msg drivers/usb/core/message.c:100 [inline] usb_control_msg+0x31b/0x550 drivers/usb/core/message.c:151 hub_port_init+0x6a5/0x2640 drivers/usb/core/hub.c:4555 vhci_hcd vhci_hcd.0: pdev(3) rhport(0) sockfd(3) hub_port_connect drivers/usb/core/hub.c:4905 [inline] hub_port_connect_change drivers/usb/core/hub.c:5088 [inline] port_event drivers/usb/core/hub.c:5194 [inline] hub_event+0x12fc/0x3230 drivers/usb/core/hub.c:5274 vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 vhci_hcd: stop threads process_one_work+0x74f/0x1620 kernel/workqueue.c:2116 vhci_hcd: release socket vhci_hcd: disconnect device worker_thread+0xcc/0xed0 kernel/workqueue.c:2250 kthread+0x338/0x400 kernel/kthread.c:232 vhci_hcd vhci_hcd.0: port 1 already used ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Showing all locks held in the system: vhci_hcd vhci_hcd.0: pdev(4) rhport(0) sockfd(3) vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) 5 locks held by kworker/0:0/3: #0: ("usb_hub_wq"){+.+.}, at: [] process_one_work+0x681/0x1620 kernel/workqueue.c:2087 #1: ((&hub->events)){+.+.}, at: [] process_one_work+0x6b4/0x1620 kernel/workqueue.c:2091 #2: (&dev->mutex){....}, at: [] device_lock include/linux/device.h:1081 [inline] #2: (&dev->mutex){....}, at: [] hub_event+0x120/0x3230 drivers/usb/core/hub.c:5220 #3: (&port_dev->status_lock){+.+.}, at: [] usb_lock_port drivers/usb/core/hub.c:2934 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_port_connect drivers/usb/core/hub.c:4904 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_port_connect_change drivers/usb/core/hub.c:5088 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] port_event drivers/usb/core/hub.c:5194 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_event+0x12e1/0x3230 drivers/usb/core/hub.c:5274 #4: (hcd->address0_mutex){+.+.}, at: [] hub_port_init+0x145/0x2640 drivers/usb/core/hub.c:4429 5 locks held by kworker/1:1/23: #0: ("usb_hub_wq"){+.+.}, at: [] process_one_work+0x681/0x1620 kernel/workqueue.c:2087 #1: ((&hub->events)){+.+.}, at: [] process_one_work+0x6b4/0x1620 kernel/workqueue.c:2091 #2: (&dev->mutex){....}, at: [] device_lock include/linux/device.h:1081 [inline] #2: (&dev->mutex){....}, at: [] hub_event+0x120/0x3230 drivers/usb/core/hub.c:5220 #3: (&port_dev->status_lock){+.+.}, at: [] usb_lock_port drivers/usb/core/hub.c:2934 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_port_connect drivers/usb/core/hub.c:4904 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_port_connect_change drivers/usb/core/hub.c:5088 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] port_event drivers/usb/core/hub.c:5194 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_event+0x12e1/0x3230 drivers/usb/core/hub.c:5274 #4: (hcd->address0_mutex){+.+.}, at: [] hub_port_init+0x145/0x2640 drivers/usb/core/hub.c:4429 1 lock held by khungtaskd/1060: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4548 5 locks held by kworker/0:2/3339: #0: ("usb_hub_wq"){+.+.}, at: [] process_one_work+0x681/0x1620 kernel/workqueue.c:2087 #1: ((&hub->events)){+.+.}, at: [] process_one_work+0x6b4/0x1620 kernel/workqueue.c:2091 #2: (&dev->mutex){....}, at: [] device_lock include/linux/device.h:1081 [inline] #2: (&dev->mutex){....}, at: [] hub_event+0x120/0x3230 drivers/usb/core/hub.c:5220 #3: (&port_dev->status_lock){+.+.}, at: [] usb_lock_port drivers/usb/core/hub.c:2934 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_port_connect drivers/usb/core/hub.c:4904 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_port_connect_change drivers/usb/core/hub.c:5088 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] port_event drivers/usb/core/hub.c:5194 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_event+0x12e1/0x3230 drivers/usb/core/hub.c:5274 #4: (hcd->address0_mutex){+.+.}, at: [] hub_port_init+0x145/0x2640 drivers/usb/core/hub.c:4429 5 locks held by kworker/1:4/5864: #0: ("usb_hub_wq"){+.+.}, at: [] process_one_work+0x681/0x1620 kernel/workqueue.c:2087 #1: ((&hub->events)){+.+.}, at: [] process_one_work+0x6b4/0x1620 kernel/workqueue.c:2091 #2: (&dev->mutex){....}, at: [] device_lock include/linux/device.h:1081 [inline] #2: (&dev->mutex){....}, at: [] hub_event+0x120/0x3230 drivers/usb/core/hub.c:5220 #3: (&port_dev->status_lock){+.+.}, at: [] usb_lock_port drivers/usb/core/hub.c:2934 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_port_connect drivers/usb/core/hub.c:4904 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_port_connect_change drivers/usb/core/hub.c:5088 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] port_event drivers/usb/core/hub.c:5194 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_event+0x12e1/0x3230 drivers/usb/core/hub.c:5274 #4: (hcd->address0_mutex){+.+.}, at: [] hub_port_init+0x145/0x2640 drivers/usb/core/hub.c:4429 5 locks held by kworker/0:5/7450: #0: ("usb_hub_wq"){+.+.}, at: [] process_one_work+0x681/0x1620 kernel/workqueue.c:2087 #1: ((&hub->events)){+.+.}, at: [] process_one_work+0x6b4/0x1620 kernel/workqueue.c:2091 #2: (&dev->mutex){....}, at: [] device_lock include/linux/device.h:1081 [inline] #2: (&dev->mutex){....}, at: [] hub_event+0x120/0x3230 drivers/usb/core/hub.c:5220 #3: (&port_dev->status_lock){+.+.}, at: [] usb_lock_port drivers/usb/core/hub.c:2934 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_port_connect drivers/usb/core/hub.c:4904 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_port_connect_change drivers/usb/core/hub.c:5088 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] port_event drivers/usb/core/hub.c:5194 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_event+0x12e1/0x3230 drivers/usb/core/hub.c:5274 #4: (hcd->address0_mutex){+.+.}, at: [] hub_port_init+0x145/0x2640 drivers/usb/core/hub.c:4429 5 locks held by kworker/0:6/7505: #0: ("usb_hub_wq"){+.+.}, at: [] process_one_work+0x681/0x1620 kernel/workqueue.c:2087 #1: ((&hub->events)){+.+.}, at: [] process_one_work+0x6b4/0x1620 kernel/workqueue.c:2091 #2: (&dev->mutex){....}, at: [] device_lock include/linux/device.h:1081 [inline] #2: (&dev->mutex){....}, at: [] hub_event+0x120/0x3230 drivers/usb/core/hub.c:5220 #3: (&port_dev->status_lock){+.+.}, at: [] usb_lock_port drivers/usb/core/hub.c:2934 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_port_connect drivers/usb/core/hub.c:4904 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_port_connect_change drivers/usb/core/hub.c:5088 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] port_event drivers/usb/core/hub.c:5194 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_event+0x12e1/0x3230 drivers/usb/core/hub.c:5274 #4: (hcd->address0_mutex){+.+.}, at: [] hub_port_init+0x145/0x2640 drivers/usb/core/hub.c:4429 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1060 Comm: khungtaskd Not tainted 4.14.216-syzkaller #0 vhci_hcd vhci_hcd.0: port 1 already used Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0x14b/0x1e7 lib/dump_stack.c:58 nmi_cpu_backtrace.cold.0+0x3c/0x78 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0xf5/0x120 lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x51b/0xa70 kernel/hung_task.c:274 kthread+0x338/0x400 kernel/kthread.c:232 vhci_hcd vhci_hcd.0: pdev(5) rhport(0) sockfd(3) vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 22707 Comm: systemd-udevd Not tainted 4.14.216-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8881f3516480 task.stack: ffff8881c4f80000 RIP: 0033:0x7f56183e8bd5 RSP: 002b:00007ffe676e9e60 EFLAGS: 00010246 RAX: 00007f5617f942a0 RBX: 00007f56181cf400 RCX: 0000000000000001 RDX: 0000000000000000 RSI: 00007f5617f8cac8 RDI: 0000000000000001 RBP: 0000000000000001 R08: 00007f56185f74f0 R09: 00007f5617f8cac8 R10: 00000000000000de R11: 00007f5617f8b4d8 R12: 0000000000000000 R13: 0000000000000000 R14: 000056090904e090 R15: 00000000ffffffff FS: 00007f56185f08c0(0000) GS:ffff8881f6600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f56181cf400 CR3: 00000001f4a40004 CR4: 00000000001606f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400