BUG: workqueue lockup - pool cpus=0 node=0 flags=0x0 nice=0 stuck for 205s! INFO: task kworker/u4:5:2247 blocked for more than 140 seconds. Not tainted 4.14.71+ #8 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/u4:5 D26160 2247 2 0x80000000 Workqueue: netns cleanup_net Call Trace: schedule+0x7f/0x1b0 kernel/sched/core.c:3490 schedule_timeout+0x710/0xe60 kernel/time/timer.c:1721 do_wait_for_common kernel/sched/completion.c:91 [inline] __wait_for_common kernel/sched/completion.c:112 [inline] wait_for_common+0x3bc/0x4e0 kernel/sched/completion.c:123 flush_work+0x3b8/0x6e0 kernel/workqueue.c:2885 flush_all_backlogs net/core/dev.c:4638 [inline] rollback_registered_many+0x505/0xac0 net/core/dev.c:7168 unregister_netdevice_many+0x43/0x210 net/core/dev.c:8231 ip6_tnl_destroy_tunnels net/ipv6/ip6_tunnel.c:2208 [inline] ip6_tnl_exit_net+0x3c8/0x580 net/ipv6/ip6_tunnel.c:2255 ops_exit_list.isra.3+0xa8/0x150 net/core/net_namespace.c:142 cleanup_net+0x3e9/0x880 net/core/net_namespace.c:483 process_one_work+0x86e/0x15c0 kernel/workqueue.c:2114 worker_thread+0xdc/0x1000 kernel/workqueue.c:2248 kthread+0x348/0x420 kernel/kthread.c:232 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:402 INFO: task kworker/1:3:5917 blocked for more than 140 seconds. Not tainted 4.14.71+ #8 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. kworker/1:3 D29312 5917 2 0x80000000 Workqueue: ipv6_addrconf addrconf_verify_work Call Trace: schedule+0x7f/0x1b0 kernel/sched/core.c:3490 schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3548 __mutex_lock_common kernel/locking/mutex.c:833 [inline] __mutex_lock+0x521/0x1480 kernel/locking/mutex.c:893 addrconf_verify_work+0xa/0x20 net/ipv6/addrconf.c:4432 process_one_work+0x86e/0x15c0 kernel/workqueue.c:2114 worker_thread+0xdc/0x1000 kernel/workqueue.c:2248 kthread+0x348/0x420 kernel/kthread.c:232 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:402 Showing all locks held in the system: 1 lock held by khungtaskd/23: #0: (tasklist_lock){.+.+}, at: [] debug_show_all_locks+0x74/0x20f kernel/locking/lockdep.c:4541 1 lock held by rsyslogd/1627: #0: (&f->f_pos_lock){+.+.}, at: [] __fdget_pos+0xa2/0xc0 fs/file.c:768 2 locks held by getty/1755: #0: (&tty->ldisc_sem){++++}, at: [] tty_ldisc_ref_wait+0x20/0x80 drivers/tty/tty_ldisc.c:275 #1: (&ldata->atomic_read_lock){+.+.}, at: [] n_tty_read+0x1ff/0x15e0 drivers/tty/n_tty.c:2142 5 locks held by kworker/u4:5/2247: #0: ("%s""netns"){+.+.}, at: [] process_one_work+0x787/0x15c0 kernel/workqueue.c:2085 #1: (net_cleanup_work){+.+.}, at: [] process_one_work+0x7bf/0x15c0 kernel/workqueue.c:2089 #2: (net_mutex){+.+.}, at: [] cleanup_net+0x14c/0x880 net/core/net_namespace.c:449 #3: (rtnl_mutex){+.+.}, at: [] ip6_tnl_exit_net+0x77/0x580 net/ipv6/ip6_tunnel.c:2254 #4: (cpu_hotplug_lock.rw_sem){++++}, at: [] get_online_cpus include/linux/cpu.h:138 [inline] #4: (cpu_hotplug_lock.rw_sem){++++}, at: [] flush_all_backlogs net/core/dev.c:4631 [inline] #4: (cpu_hotplug_lock.rw_sem){++++}, at: [] rollback_registered_many+0x416/0xac0 net/core/dev.c:7168 3 locks held by kworker/1:3/5917: #0: ("%s"("ipv6_addrconf")){+.+.}, at: [] process_one_work+0x787/0x15c0 kernel/workqueue.c:2085 #1: ((addr_chk_work).work){+.+.}, at: [] process_one_work+0x7bf/0x15c0 kernel/workqueue.c:2089 #2: (rtnl_mutex){+.+.}, at: [] addrconf_verify_work+0xa/0x20 net/ipv6/addrconf.c:4432 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 23 Comm: khungtaskd Not tainted 4.14.71+ #8 Call Trace: __dump_stack lib/dump_stack.c:17 [inline] dump_stack+0xb9/0x11b lib/dump_stack.c:53 nmi_cpu_backtrace.cold.0+0x47/0x85 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x121/0x146 lib/nmi_backtrace.c:62 trigger_all_cpu_backtrace include/linux/nmi.h:138 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:196 [inline] watchdog+0x574/0xa70 kernel/hung_task.c:252 kthread+0x348/0x420 kernel/kthread.c:232 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:402 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 11808 Comm: syz-executor4 Not tainted 4.14.71+ #8 task: ffff8801a1332f00 task.stack: ffff8801a14a0000 RIP: 0010:rdtsc arch/x86/include/asm/msr.h:191 [inline] RIP: 0010:rdtsc_ordered arch/x86/include/asm/msr.h:218 [inline] RIP: 0010:delay_tsc+0x47/0xb0 arch/x86/lib/delay.c:61 RSP: 0000:ffff8801dba078e0 EFLAGS: 00000046 RAX: 00000000e418aeef RBX: 000000e6e418ae80 RCX: 0000000000000000 RDX: 00000000000000e6 RSI: ffffffffb8550080 RDI: ffffffffb85500c0 RBP: 000000e6e418aaa9 R08: 1ffffffff73c4c01 R09: 0000000000000002 R10: 0000000000000000 R11: 0000000000000001 R12: 00000000000008fd R13: 0000000000000000 R14: fffffbfff7523b35 R15: ffffffffba91db92 FS: 00007faee635e700(0000) GS:ffff8801dba00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000002334978 CR3: 00000001d483c004 CR4: 00000000001606b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: wait_for_xmitr+0x66/0x1e0 drivers/tty/serial/8250/8250_port.c:2040 serial8250_console_putchar+0x19/0x50 drivers/tty/serial/8250/8250_port.c:3184 uart_console_write+0x4b/0xd0 drivers/tty/serial/serial_core.c:1883 serial8250_console_write+0x51b/0x800 drivers/tty/serial/8250/8250_port.c:3250 call_console_drivers kernel/printk/printk.c:1574 [inline] console_unlock+0x5b9/0xb50 kernel/printk/printk.c:2242 vprintk_emit+0x112/0x150 kernel/printk/printk.c:1766 vprintk_func+0x58/0x159 kernel/printk/printk_safe.c:401 printk+0xa7/0xcf kernel/printk/printk.c:1838 wq_watchdog_timer_fn.cold.24+0x4b/0x70 kernel/workqueue.c:5473 call_timer_fn+0x163/0x6a0 kernel/time/timer.c:1279 expire_timers+0x1f3/0x4a0 kernel/time/timer.c:1318 __run_timers kernel/time/timer.c:1634 [inline] run_timer_softirq+0x3a5/0x560 kernel/time/timer.c:1649 __do_softirq+0x215/0x997 kernel/softirq.c:288 invoke_softirq kernel/softirq.c:368 [inline] irq_exit+0x10f/0x150 kernel/softirq.c:409 exiting_irq arch/x86/include/asm/apic.h:648 [inline] smp_apic_timer_interrupt+0x188/0x5f0 arch/x86/kernel/apic/apic.c:1064 apic_timer_interrupt+0x84/0x90 arch/x86/entry/entry_64.S:787 RIP: 0033:0x40157b RSP: 002b:00007faee635d690 EFLAGS: 00000286 ORIG_RAX: ffffffffffffff10 RAX: 00000000cf96c6d1 RBX: 0000000000000007 RCX: 0000000000457679 RDX: 0000000000000000 RSI: 00007faee635d6c0 RDI: 0000000000000007 RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff R13: 00000000004d7950 R14: 00000000004c48c6 R15: 0000000000000000 Code: ae e8 0f 31 48 c1 e2 20 48 09 c2 48 89 d5 eb 16 f3 90 bf 01 00 00 00 e8 98 f3 92 fe e8 a3 4b 34 ff 44 39 e8 75 36 0f ae e8 0f 31 <48> c1 e2 20 48 89 d3 48 09 c3 48 89 d8 48 29 e8 4c 39 e0 73 24