INFO: task kworker/1:0:18 blocked for more than 140 seconds. Not tainted 4.14.262-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/1:0 D27064 18 2 0x80000000 Workqueue: usb_hub_wq hub_event Call Trace: context_switch kernel/sched/core.c:2811 [inline] __schedule+0x88b/0x1de0 kernel/sched/core.c:3387 schedule+0x8d/0x1b0 kernel/sched/core.c:3431 usb_kill_urb.part.0+0x125/0x190 drivers/usb/core/urb.c:691 usb_kill_urb+0x7c/0x90 drivers/usb/core/urb.c:686 usb_start_wait_urb+0x209/0x440 drivers/usb/core/message.c:62 usb_internal_control_msg drivers/usb/core/message.c:100 [inline] usb_control_msg+0x302/0x450 drivers/usb/core/message.c:151 hub_port_init+0xf27/0x28b0 drivers/usb/core/hub.c:4599 hub_port_connect drivers/usb/core/hub.c:4954 [inline] hub_port_connect_change drivers/usb/core/hub.c:5144 [inline] port_event drivers/usb/core/hub.c:5250 [inline] hub_event+0x1948/0x3f60 drivers/usb/core/hub.c:5330 process_one_work+0x793/0x14a0 kernel/workqueue.c:2117 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2251 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 INFO: task kworker/0:4:9047 blocked for more than 140 seconds. Not tainted 4.14.262-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/0:4 D27688 9047 2 0x80000000 Workqueue: usb_hub_wq hub_event Call Trace: context_switch kernel/sched/core.c:2811 [inline] __schedule+0x88b/0x1de0 kernel/sched/core.c:3387 schedule+0x8d/0x1b0 kernel/sched/core.c:3431 usb_kill_urb.part.0+0x125/0x190 drivers/usb/core/urb.c:691 usb_kill_urb+0x7c/0x90 drivers/usb/core/urb.c:686 usb_start_wait_urb+0x209/0x440 drivers/usb/core/message.c:62 usb_internal_control_msg drivers/usb/core/message.c:100 [inline] usb_control_msg+0x302/0x450 drivers/usb/core/message.c:151 hub_port_init+0xf27/0x28b0 drivers/usb/core/hub.c:4599 hub_port_connect drivers/usb/core/hub.c:4954 [inline] hub_port_connect_change drivers/usb/core/hub.c:5144 [inline] port_event drivers/usb/core/hub.c:5250 [inline] hub_event+0x1948/0x3f60 drivers/usb/core/hub.c:5330 process_one_work+0x793/0x14a0 kernel/workqueue.c:2117 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2251 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Showing all locks held in the system: 5 locks held by kworker/1:0/18: #0: ("usb_hub_wq"){+.+.}, at: [] process_one_work+0x6b0/0x14a0 kernel/workqueue.c:2088 #1: ((&hub->events)){+.+.}, at: [] process_one_work+0x6e6/0x14a0 kernel/workqueue.c:2092 #2: (&dev->mutex){....}, at: [] device_lock include/linux/device.h:1082 [inline] #2: (&dev->mutex){....}, at: [] hub_event+0x108/0x3f60 drivers/usb/core/hub.c:5276 #3: (&port_dev->status_lock){+.+.}, at: [] usb_lock_port drivers/usb/core/hub.c:2936 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_port_connect drivers/usb/core/hub.c:4920 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_port_connect_change drivers/usb/core/hub.c:5144 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] port_event drivers/usb/core/hub.c:5250 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_event+0x15c0/0x3f60 drivers/usb/core/hub.c:5330 #4: (hcd->address0_mutex){+.+.}, at: [] hub_port_connect drivers/usb/core/hub.c:4921 [inline] #4: (hcd->address0_mutex){+.+.}, at: [] hub_port_connect_change drivers/usb/core/hub.c:5144 [inline] #4: (hcd->address0_mutex){+.+.}, at: [] port_event drivers/usb/core/hub.c:5250 [inline] #4: (hcd->address0_mutex){+.+.}, at: [] hub_event+0x15ea/0x3f60 drivers/usb/core/hub.c:5330 1 lock held by khungtaskd/1534: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548 5 locks held by kworker/0:4/9047: #0: ("usb_hub_wq"){+.+.}, at: [] process_one_work+0x6b0/0x14a0 kernel/workqueue.c:2088 #1: ((&hub->events)){+.+.}, at: [] process_one_work+0x6e6/0x14a0 kernel/workqueue.c:2092 #2: (&dev->mutex){....}, at: [] device_lock include/linux/device.h:1082 [inline] #2: (&dev->mutex){....}, at: [] hub_event+0x108/0x3f60 drivers/usb/core/hub.c:5276 #3: (&port_dev->status_lock){+.+.}, at: [] usb_lock_port drivers/usb/core/hub.c:2936 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_port_connect drivers/usb/core/hub.c:4920 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_port_connect_change drivers/usb/core/hub.c:5144 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] port_event drivers/usb/core/hub.c:5250 [inline] #3: (&port_dev->status_lock){+.+.}, at: [] hub_event+0x15c0/0x3f60 drivers/usb/core/hub.c:5330 #4: (hcd->address0_mutex){+.+.}, at: [] hub_port_connect drivers/usb/core/hub.c:4921 [inline] #4: (hcd->address0_mutex){+.+.}, at: [] hub_port_connect_change drivers/usb/core/hub.c:5144 [inline] #4: (hcd->address0_mutex){+.+.}, at: [] port_event drivers/usb/core/hub.c:5250 [inline] #4: (hcd->address0_mutex){+.+.}, at: [] hub_event+0x15ea/0x3f60 drivers/usb/core/hub.c:5330 2 locks held by kworker/u4:7/20921: #0: ("events_unbound"){+.+.}, at: [] process_one_work+0x6b0/0x14a0 kernel/workqueue.c:2088 #1: ((&sub_info->work)){+.+.}, at: [] process_one_work+0x6e6/0x14a0 kernel/workqueue.c:2092 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 1534 Comm: khungtaskd Not tainted 4.14.262-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+0x1b2/0x281 lib/dump_stack.c:58 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x13a/0x180 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:140 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:195 [inline] watchdog+0x5b9/0xb40 kernel/hung_task.c:274 kthread+0x30d/0x420 kernel/kthread.c:232 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: 4615 Comm: systemd-journal Not tainted 4.14.262-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 task: ffff8880a1a1a600 task.stack: ffff8880a1a20000 RIP: 0010:preempt_count_add+0x1c/0x170 kernel/sched/core.c:3102 RSP: 0018:ffff8880a1a27b20 EFLAGS: 00000a02 RAX: dffffc0000000000 RBX: ffffffff8bec9d40 RCX: 1ffff11014344fa9 RDX: 1ffffffff17d93a8 RSI: 000000000000166a RDI: 0000000000000001 RBP: 0000000000000001 R08: ffffffff8b9c7388 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000002 R13: ffff8880a1a27d10 R14: ffff8880a1a27d10 R15: 0000000000000000 FS: 00007f83f9c7e8c0(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f83f720e000 CR3: 00000000a22ff000 CR4: 00000000003406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __raw_spin_lock include/linux/spinlock_api_smp.h:141 [inline] _raw_spin_lock+0xe/0x40 kernel/locking/spinlock.c:152 spin_lock include/linux/spinlock.h:317 [inline] lockref_get_not_dead+0x14/0x70 lib/lockref.c:180 legitimize_path.isra.0+0x78/0x190 fs/namei.c:642 unlazy_walk+0xea/0x4a0 fs/namei.c:694 complete_walk+0xa5/0x1f0 fs/namei.c:807 path_lookupat+0x23f/0x780 fs/namei.c:2351 filename_lookup+0x18a/0x510 fs/namei.c:2377 user_path_at include/linux/namei.h:57 [inline] SYSC_faccessat fs/open.c:403 [inline] SyS_faccessat+0x21b/0x680 fs/open.c:353 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x7f83f8f399c7 RSP: 002b:00007ffc8cabbc38 EFLAGS: 00000246 ORIG_RAX: 0000000000000015 RAX: ffffffffffffffda RBX: 00007ffc8cabeb50 RCX: 00007f83f8f399c7 RDX: 00007f83f99aaa00 RSI: 0000000000000000 RDI: 00005579fcaef9a3 RBP: 00007ffc8cabbc70 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000069 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007ffc8cabeb50 R15: 00007ffc8cabc160 Code: e9 72 ff ff ff 66 2e 0f 1f 84 00 00 00 00 00 48 b8 00 00 00 00 00 fc ff df 55 89 fd 53 48 c7 c3 40 9d ec 8b 48 89 da 48 c1 ea 03 <0f> b6 14 02 48 89 d8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 ---------------- Code disassembly (best guess): 0: e9 72 ff ff ff jmpq 0xffffff77 5: 66 2e 0f 1f 84 00 00 nopw %cs:0x0(%rax,%rax,1) c: 00 00 00 f: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax 16: fc ff df 19: 55 push %rbp 1a: 89 fd mov %edi,%ebp 1c: 53 push %rbx 1d: 48 c7 c3 40 9d ec 8b mov $0xffffffff8bec9d40,%rbx 24: 48 89 da mov %rbx,%rdx 27: 48 c1 ea 03 shr $0x3,%rdx * 2b: 0f b6 14 02 movzbl (%rdx,%rax,1),%edx <-- trapping instruction 2f: 48 89 d8 mov %rbx,%rax 32: 83 e0 07 and $0x7,%eax 35: 83 c0 03 add $0x3,%eax 38: 38 d0 cmp %dl,%al 3a: 7c 08 jl 0x44 3c: 84 d2 test %dl,%dl 3e: 0f .byte 0xf 3f: 85 .byte 0x85