INFO: task hung in __l2tp_session

loop_reread_partitions: partition scan of loop0 (mñs=zŠ$/Ø™àc?_Î¨ûZUØ»¤Ù	Ç¡$Ø¬9Ñ=É:€ò/ùý5¨Dóèµäå“Q7¯oâQ4C]) failed (rc=-13)
INFO: task kworker/u4:2:30 blocked for more than 120 seconds.
      Not tainted 4.16.0+ #4
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kworker/u4:2    D12728    30      2 0x80000000
Workqueue: l2tp l2tp_tunnel_del_work
Call Trace:
 context_switch kernel/sched/core.c:2848 [inline]
 __schedule+0x807/0x1e40 kernel/sched/core.c:3490
 schedule+0xef/0x430 kernel/sched/core.c:3549
 schedule_timeout+0x1b5/0x240 kernel/time/timer.c:1777
 do_wait_for_common kernel/sched/completion.c:83 [inline]
 __wait_for_common kernel/sched/completion.c:104 [inline]
 wait_for_common kernel/sched/completion.c:115 [inline]
 wait_for_completion+0x3e7/0x870 kernel/sched/completion.c:136
 __wait_rcu_gp+0x257/0x350 kernel/rcu/update.c:414
 synchronize_sched.part.64+0xe3/0xf0 kernel/rcu/tree.c:3209
 synchronize_sched+0x76/0xf0 kernel/rcu/tree.c:3210
 synchronize_rcu include/linux/rcupdate.h:94 [inline]
 __l2tp_session_unhash+0x59b/0x8d0 net/l2tp/l2tp_core.c:1639
 l2tp_tunnel_closeall+0x29e/0x430 net/l2tp/l2tp_core.c:1245
 l2tp_tunnel_del_work+0xdf/0x830 net/l2tp/l2tp_core.c:1285
 process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145
 worker_thread+0x1cc/0x1440 kernel/workqueue.c:2279
 kthread+0x345/0x410 kernel/kthread.c:238
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:411

Showing all locks held in the system:
2 locks held by kworker/u4:2/30:
 #0: 000000003a29d90f ((wq_completion)"l2tp"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline]
 #0: 000000003a29d90f ((wq_completion)"l2tp"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline]
 #0: 000000003a29d90f ((wq_completion)"l2tp"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline]
 #0: 000000003a29d90f ((wq_completion)"l2tp"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:57 [inline]
 #0: 000000003a29d90f ((wq_completion)"l2tp"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline]
 #0: 000000003a29d90f ((wq_completion)"l2tp"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline]
 #0: 000000003a29d90f ((wq_completion)"l2tp"){+.+.}, at: process_one_work+0xaef/0x1b50 kernel/workqueue.c:2116
 #1: 000000008f9beb62 ((work_completion)(&tunnel->del_work)){+.+.}, at: process_one_work+0xb46/0x1b50 kernel/workqueue.c:2120
2 locks held by khungtaskd/882:
 #0: 0000000078c69238 (rcu_read_lock){....}, at: check_hung_uninterruptible_tasks kernel/hung_task.c:175 [inline]
 #0: 0000000078c69238 (rcu_read_lock){....}, at: watchdog+0x1ff/0xf60 kernel/hung_task.c:249
 #1: 000000004baf3b67 (tasklist_lock){.+.+}, at: debug_show_all_locks+0xde/0x34a kernel/locking/lockdep.c:4470
2 locks held by getty/4423:
 #0: 00000000d1016494 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 0000000049828d71 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4424:
 #0: 00000000fbbead26 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 000000001462df95 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4425:
 #0: 00000000e1d92176 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 00000000d0f0bad1 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4426:
 #0: 000000005ca596b8 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
INFO: rcu_sched self-detected stall on CPU
 #1: 0000000001ff906a (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
	0-....: (124999 ticks this GP) idle=4b2/1/4611686018427387906 softirq=148537/148537 fqs=31050 
2 locks held by getty/4427:
 #0: 000000004db9550f (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 0000000084a2d425 (
	 (t=125000 jiffies g=85329 c=85328 q=1249)
NMI backtrace for cpu 0
&ldata->atomic_read_lock
CPU: 0 PID: 3602 Comm: syz-executor0 Not tainted 4.16.0+ #4
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
){+.+.}
Call Trace:
 <IRQ>
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1b9/0x294 lib/dump_stack.c:113
, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
2 locks held by getty/4428:
 nmi_cpu_backtrace.cold.4+0x19/0xce lib/nmi_backtrace.c:103
 #0: 
 nmi_trigger_cpumask_backtrace+0x151/0x192 lib/nmi_backtrace.c:62
 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38
00000000f6347a6c
 trigger_single_cpu_backtrace include/linux/nmi.h:156 [inline]
 rcu_dump_cpu_stacks+0x175/0x1c2 kernel/rcu/tree.c:1376
 (
 print_cpu_stall kernel/rcu/tree.c:1525 [inline]
 check_cpu_stall.isra.61.cold.80+0x36c/0x59a kernel/rcu/tree.c:1593
&tty->ldisc_sem
){++++}
, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 #1: 
0000000034756510
 (
&ldata->atomic_read_lock
){+.+.}
, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131
 __rcu_pending kernel/rcu/tree.c:3356 [inline]
 rcu_pending kernel/rcu/tree.c:3401 [inline]
 rcu_check_callbacks+0x21b/0xad0 kernel/rcu/tree.c:2763
2 locks held by getty/4429:
 #0: 
00000000e988b65f
 (
&tty->ldisc_sem
){++++}
, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:365
 update_process_times+0x2d/0x70 kernel/time/timer.c:1636
 tick_sched_handle+0xa0/0x180 kernel/time/tick-sched.c:171
 #1: 
 tick_sched_timer+0x42/0x130 kernel/time/tick-sched.c:1179
 __run_hrtimer kernel/time/hrtimer.c:1337 [inline]
 __hrtimer_run_queues+0x3e3/0x10a0 kernel/time/hrtimer.c:1399
00000000e4ece6ab
 (
&ldata->atomic_read_lock
){+.+.}
, at: n_tty_read+0x321/0x1cc0 drivers/tty/n_tty.c:2131

 hrtimer_interrupt+0x286/0x650 kernel/time/hrtimer.c:1457
=============================================

 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1025 [inline]
 smp_apic_timer_interrupt+0x15d/0x710 arch/x86/kernel/apic/apic.c:1050