bisecting fixing commit since cbfa1702aaf69b2311ea1b35e04f113c48368c67 building syzkaller on 1a3f94087169f62f9a5832828f62b4900e98b781 testing commit cbfa1702aaf69b2311ea1b35e04f113c48368c67 with gcc (GCC) 8.1.0 kernel signature: 3b14d0c7b03408f63e10e5d44fce0ba3c9acfbdc665d0edbbf5896beb6da38b6 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: INFO: task hung in hub_port_init run #6: crashed: INFO: task hung in hub_port_init 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 testing current HEAD 3f2ecb86cb909da0b9157fd2952ad79924cbe5ae testing commit 3f2ecb86cb909da0b9157fd2952ad79924cbe5ae with gcc (GCC) 8.1.0 kernel signature: 0daab7fd9132187bdbd8906586184ffd1a04a67737e6ef232ab3b2b528034a07 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 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: INFO: task hung in hub_port_init run #6: crashed: INFO: task hung in hub_port_init 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: 32m33.683490396s (build: 18m30.057757624s, test: 13m20.002238004s) the crash still happens on HEAD commit msg: Linux 4.14.212 crash: INFO: task hung in hub_port_init vhci_hcd vhci_hcd.0: pdev(4) 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 vhci_hcd: release socket INFO: task kworker/1:1:23 blocked for more than 140 seconds. Not tainted 4.14.212-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/1:1 D25936 23 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 vhci_hcd: disconnect device 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(1) rhport(0) sockfd(3) vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) vhci_hcd vhci_hcd.0: port 1 already used usb_start_wait_urb+0x1fb/0x260 drivers/usb/core/message.c:62 vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 vhci_hcd: stop threads vhci_hcd vhci_hcd.0: pdev(0) rhport(0) sockfd(3) vhci_hcd vhci_hcd.0: port 1 already used vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) 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 process_one_work+0x74f/0x1620 kernel/workqueue.c:2116 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/1:3:3363 blocked for more than 140 seconds. Not tainted 4.14.212-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/1:3 D26272 3363 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 vhci_hcd: release socket vhci_hcd: disconnect device vhci_hcd: connection closed vhci_hcd vhci_hcd.0: pdev(5) rhport(0) sockfd(3) vhci_hcd vhci_hcd.0: port 1 already used 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 vhci_hcd.0: pdev(2) rhport(0) sockfd(3) vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) 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 vhci_hcd: disconnect device vhci_hcd: stop threads vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 vhci_hcd: release socket 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 vhci_hcd: release socket process_one_work+0x74f/0x1620 kernel/workqueue.c:2116 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 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 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 vhci_hcd: release socket vhci_hcd: disconnect device INFO: task kworker/0:3:6182 blocked for more than 140 seconds. Not tainted 4.14.212-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/0:3 D26240 6182 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 vhci_hcd vhci_hcd.0: port 1 already used schedule+0x7f/0x1b0 kernel/sched/core.c:3428 usb_kill_urb+0x193/0x210 drivers/usb/core/urb.c:691 vhci_hcd vhci_hcd.0: pdev(4) 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 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: stop threads 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: release socket process_one_work+0x74f/0x1620 kernel/workqueue.c:2116 vhci_hcd: disconnect device vhci_hcd vhci_hcd.0: pdev(1) rhport(0) sockfd(3) worker_thread+0xcc/0xed0 kernel/workqueue.c:2250 vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) kthread+0x338/0x400 kernel/kthread.c:232 vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 vhci_hcd: stop threads vhci_hcd: release socket ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 vhci_hcd: disconnect device INFO: task kworker/1:4:6848 blocked for more than 140 seconds. vhci_hcd vhci_hcd.0: port 1 already used Not tainted 4.14.212-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) vhci_hcd vhci_hcd.0: port 1 already used kworker/1:4 D26840 6848 2 0x80000000 vhci_hcd vhci_hcd.0: pdev(5) rhport(0) sockfd(3) vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 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 Workqueue: usb_hub_wq hub_event vhci_hcd vhci_hcd.0: port 1 already used vhci_hcd: stop threads 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 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 schedule+0x7f/0x1b0 kernel/sched/core.c:3428 vhci_hcd: stop threads usb_kill_urb+0x193/0x210 drivers/usb/core/urb.c:691 vhci_hcd: release socket vhci_hcd: disconnect device 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 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 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/0:4:7234 blocked for more than 140 seconds. Not tainted 4.14.212-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/0:4 D26336 7234 2 0x80000000 Workqueue: usb_hub_wq hub_event vhci_hcd vhci_hcd.0: port 1 already used 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 vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) usb_kill_urb+0x193/0x210 drivers/usb/core/urb.c:691 vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 vhci_hcd: stop threads usb_start_wait_urb+0x1fb/0x260 drivers/usb/core/message.c:62 vhci_hcd: release socket vhci_hcd: disconnect device 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: port 1 already used 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: pdev(4) 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 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 vhci_hcd vhci_hcd.0: pdev(1) rhport(0) sockfd(3) INFO: task kworker/0:5:7451 blocked for more than 140 seconds. 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 Not tainted 4.14.212-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. vhci_hcd: stop threads kworker/0:5 D26336 7451 2 0x80000000 vhci_hcd: release socket Workqueue: usb_hub_wq hub_event vhci_hcd: disconnect device Call Trace: context_switch kernel/sched/core.c:2808 [inline] __schedule+0x824/0x1ee0 kernel/sched/core.c:3384 vhci_hcd vhci_hcd.0: port 1 already used schedule+0x7f/0x1b0 kernel/sched/core.c:3428 vhci_hcd vhci_hcd.0: port 1 already used 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: pdev(5) rhport(0) sockfd(3) vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) vhci_hcd vhci_hcd.0: pdev(0) 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 vhci_hcd vhci_hcd.0: port 1 already used 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 vhci_hcd: disconnect device vhci_hcd: connection closed 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: stop threads vhci_hcd vhci_hcd.0: pdev(2) rhport(0) sockfd(3) vhci_hcd: release socket vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) process_one_work+0x74f/0x1620 kernel/workqueue.c:2116 vhci_hcd: disconnect device vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 worker_thread+0xcc/0xed0 kernel/workqueue.c:2250 kthread+0x338/0x400 kernel/kthread.c:232 vhci_hcd: stop threads vhci_hcd: release socket ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 vhci_hcd: disconnect device Showing all locks held in the system: 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/1067: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4548 vhci_hcd vhci_hcd.0: port 1 already used 5 locks held by kworker/1:3/3363: #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/0:3/6182: #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/1:4/6848: #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/0:4/7234: #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/0:5/7451: #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: 1067 Comm: khungtaskd Not tainted 4.14.212-syzkaller #0 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/0x1f1 lib/dump_stack.c:58 nmi_cpu_backtrace.cold.0+0x3c/0x78 lib/nmi_backtrace.c:101 vhci_hcd vhci_hcd.0: pdev(3) rhport(0) sockfd(3) vhci_hcd vhci_hcd.0: devid(0) speed(2) speed_str(full-speed) nmi_trigger_cpumask_backtrace+0xf5/0x119 lib/nmi_backtrace.c:62 vhci_hcd: cannot find a urb of seqnum 0 max seqnum 2 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 vhci_hcd: stop threads 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 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Sending NMI from CPU 1 to CPUs 0: vhci_hcd: release socket NMI backtrace for cpu 0 CPU: 0 PID: 5 Comm: kworker/u4:0 Not tainted 4.14.212-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: usbip_event event_handler task: ffff8881f531c140 task.stack: ffff8881f5328000 RIP: 0010:__lock_acquire+0x269/0x42d0 kernel/locking/lockdep.c:3396 RSP: 0018:ffff8881f6607c60 EFLAGS: 00000006 RAX: ffffffff89583310 RBX: 0000000000000000 RCX: 0000000000000002 RDX: 1ffffffff0ff25ca RSI: 0000000000000000 RDI: ffffffff87f92e50 RBP: ffff8881f6607e28 R08: 0000000000000001 R09: 0000000000000001 R10: 0000000000000001 R11: ffff8881f531c140 R12: ffffffff87f92e48 R13: 0000000000000000 R14: 0000000000000001 R15: 0000000000000000 FS: 0000000000000000(0000) GS:ffff8881f6600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000020004780 CR3: 0000000007e6a001 CR4: 00000000001606f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x17e/0x3e0 kernel/locking/lockdep.c:3998 seqcount_lockdep_reader_access include/linux/seqlock.h:81 [inline] read_seqcount_begin include/linux/seqlock.h:164 [inline] ktime_get_update_offsets_now+0xad/0x370 kernel/time/timekeeping.c:2229 hrtimer_update_base kernel/time/hrtimer.c:505 [inline] hrtimer_interrupt+0x130/0x600 kernel/time/hrtimer.c:1309 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1075 [inline] smp_apic_timer_interrupt+0x11f/0x5d0 arch/x86/kernel/apic/apic.c:1100 apic_timer_interrupt+0x9a/0xa0 arch/x86/entry/entry_64.S:793 RIP: 0010:arch_local_irq_restore arch/x86/include/asm/paravirt.h:779 [inline] RIP: 0010:console_trylock_spinning kernel/printk/printk.c:1685 [inline] RIP: 0010:vprintk_emit+0x42c/0x4e0 kernel/printk/printk.c:1922 RSP: 0018:ffff8881f532fb40 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff10 RAX: dffffc0000000000 RBX: 0000000000000286 RCX: 1ffff1103ea63942 RDX: 0000000000000000 RSI: ffff8881f531c9f0 RDI: 0000000000000286 RBP: ffff8881f532fb90 R08: ffff8881f531ca10 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 1ffffffff0fe2bc0 R13: 1ffffffff0fe2bc2 R14: 0000000000000000 R15: 1ffffffff0fe2bc1 vprintk_default+0x1a/0x20 kernel/printk/printk.c:1963 vprintk_func+0x49/0x12c kernel/printk/printk_safe.c:401 printk+0x91/0xab kernel/printk/printk.c:1996 vhci_shutdown_connection.cold.6+0xea/0x7a6 drivers/usb/usbip/vhci_hcd.c:1046 event_handler+0x169/0x360 drivers/usb/usbip/usbip_event.c:92 process_one_work+0x74f/0x1620 kernel/workqueue.c:2116 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 Code: 49 8d 7c dc 08 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 c7 2e 00 00 49 8b 44 dc 08 48 85 c0 0f 84 03 ff ff ff f0 ff 80 38 01 00 00 <49> 8d 9b 80 08 00 00 48 ba 00 00 00 00 00 fc ff df 48 89 de 48