__netdev_start_xmit include/linux/netdevice.h:4039 [inline] netdev_start_xmit include/linux/netdevice.h:4048 [inline] xmit_one net/core/dev.c:3005 [inline] dev_hard_start_xmit+0x188/0x890 net/core/dev.c:3021 sch_direct_xmit+0x251/0x500 net/sched/sch_generic.c:186 __dev_xmit_skb net/core/dev.c:3214 [inline] __dev_queue_xmit+0x1ab0/0x2480 net/core/dev.c:3489 INFO: task kworker/0:4:9248 blocked for more than 140 seconds. Not tainted 4.14.206-syzkaller #0 neigh_hh_output include/net/neighbour.h:490 [inline] neigh_output include/net/neighbour.h:498 [inline] ip6_finish_output2+0xc6a/0x1f10 net/ipv6/ip6_output.c:120 ip6_fragment+0x2516/0x2f40 net/ipv6/ip6_output.c:745 ip6_finish_output+0x62e/0xaf0 net/ipv6/ip6_output.c:152 NF_HOOK_COND include/linux/netfilter.h:239 [inline] ip6_output+0x1c5/0x660 net/ipv6/ip6_output.c:171 dst_output include/net/dst.h:470 [inline] ip6_local_out+0x93/0x170 net/ipv6/output_core.c:178 ip6_send_skb+0x9b/0x2f0 net/ipv6/ip6_output.c:1688 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. ip6_push_pending_frames+0xaf/0xd0 net/ipv6/ip6_output.c:1708 rawv6_push_pending_frames net/ipv6/raw.c:618 [inline] rawv6_sendmsg+0x230b/0x2df0 net/ipv6/raw.c:959 kworker/0:4 D inet_sendmsg+0x11a/0x4e0 net/ipv4/af_inet.c:762 sock_sendmsg_nosec net/socket.c:646 [inline] sock_sendmsg+0xb5/0x100 net/socket.c:656 sock_no_sendpage+0xe2/0x110 net/core/sock.c:2595 26224 9248 2 0x80000000 kernel_sendpage net/socket.c:3407 [inline] sock_sendpage+0xdf/0x140 net/socket.c:871 Workqueue: usb_hub_wq hub_event pipe_to_sendpage+0x226/0x2d0 fs/splice.c:451 splice_from_pipe_feed fs/splice.c:502 [inline] __splice_from_pipe+0x326/0x7a0 fs/splice.c:626 splice_from_pipe fs/splice.c:661 [inline] generic_splice_sendpage+0xc1/0x110 fs/splice.c:832 do_splice_from fs/splice.c:851 [inline] do_splice fs/splice.c:1147 [inline] SYSC_splice fs/splice.c:1402 [inline] SyS_splice+0xd59/0x1380 fs/splice.c:1382 Call Trace: do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292 context_switch kernel/sched/core.c:2808 [inline] __schedule+0x88b/0x1de0 kernel/sched/core.c:3384 entry_SYSCALL_64_after_hwframe+0x46/0xbb RIP: 0033:0x45deb9 RSP: 002b:00007fcda32d3c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000113 RAX: ffffffffffffffda RBX: 0000000000035140 RCX: 000000000045deb9 RDX: 0000000000000005 RSI: 0000000000000000 RDI: 0000000000000003 RBP: 00007fcda32d3ca0 R08: 000000000004ffe0 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000029 R13: 00007fffd0cb625f R14: 00007fcda32d49c0 R15: 000000000118bfd4 schedule+0x8d/0x1b0 kernel/sched/core.c:3428 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 usb_get_descriptor+0xc0/0x160 drivers/usb/core/message.c:652 usb_get_device_descriptor+0x71/0xd0 drivers/usb/core/message.c:924 hub_port_init+0x629/0x2970 drivers/usb/core/hub.c:4647 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+0x1923/0x3dc0 drivers/usb/core/hub.c:5274 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250 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: 1 lock held by khungtaskd/1531: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x7c/0x21a kernel/locking/lockdep.c:4548 1 lock held by in:imklog/7673: #0: (&f->f_pos_lock){+.+.}, at: [] __fdget_pos+0x1fb/0x2b0 fs/file.c:769 5 locks held by kworker/0:4/9248: #0: ("usb_hub_wq"){+.+.}, at: [] process_one_work+0x6b0/0x14a0 kernel/workqueue.c:2087 #1: ((&hub->events)){+.+.}, at: [] process_one_work+0x6e6/0x14a0 kernel/workqueue.c:2091 #2: (&dev->mutex){....}, at: [] device_lock include/linux/device.h:1081 [inline] #2: (&dev->mutex){....}, at: [] hub_event+0x108/0x3dc0 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+0x190e/0x3dc0 drivers/usb/core/hub.c:5274 #4: (hcd->address0_mutex){+.+.}, at: [] hub_port_init+0x15b/0x2970 drivers/usb/core/hub.c:4429 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1531 Comm: khungtaskd Not tainted 4.14.206-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+0x1b2/0x283 lib/dump_stack.c:58 nmi_cpu_backtrace.cold+0x57/0x93 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x13a/0x17f 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 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 5 Comm: kworker/u4:0 Not tainted 4.14.206-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: bat_events batadv_nc_worker task: ffff8880b5ff0140 task.stack: ffff8880b5ff8000 RIP: 0010:__lock_acquire+0x623/0x3f20 kernel/locking/lockdep.c:3468 RSP: 0018:ffff8880b5fffaa8 EFLAGS: 00000802 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 1ffff11016bfe147 RDX: 0000000000000004 RSI: ffff8880b5ff0a18 RDI: ffffffff8b9d0180 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000020012 R10: ffff8880b5ff0a18 R11: ffff8880b5ff0140 R12: ffff8880b5ff0a30 R13: 0000000000000012 R14: 0000000000000012 R15: ffffffff8beb2d40 FS: 0000000000000000(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f9122ef0000 CR3: 00000000665a8000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: lock_acquire+0x170/0x3f0 kernel/locking/lockdep.c:3998 rcu_lock_acquire include/linux/rcupdate.h:242 [inline] rcu_read_lock include/linux/rcupdate.h:629 [inline] batadv_nc_purge_orig_hash net/batman-adv/network-coding.c:416 [inline] batadv_nc_worker+0x124/0xc50 net/batman-adv/network-coding.c:726 process_one_work+0x793/0x14a0 kernel/workqueue.c:2116 worker_thread+0x5cc/0xff0 kernel/workqueue.c:2250 kthread+0x30d/0x420 kernel/kthread.c:232 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404 Code: 34 e3 ff ff 4c 8b 5c 24 20 85 c0 4c 8b 54 24 28 0f 84 70 fb ff ff 48 b8 00 00 00 00 00 fc ff df 4c 89 fa 48 c1 ea 03 0f b6 14 02 <4c> 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 8e 08 00 00