------------[ cut here ]------------
WARNING: CPU: 1 PID: 0 at net/ipv4/af_inet.c:167 inet_sock_destruct+0x5f6/0x7b0 net/ipv4/af_inet.c:167
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.9.77-g9c3804b #26
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
 ffff8801db307cb8 ffffffff81d941c9 ffffffff83a47bc0 ffff8801db307d90
 ffffffff83f2f000 ffffffff832ebc36 0000000000000009 ffff8801db307d80
 ffffffff8142f3c1 0000000041b58ab3 ffffffff8418ab70 ffffffff8142f205
Call Trace:
 <IRQ> [   24.190280]  [<ffffffff81d941c9>] __dump_stack lib/dump_stack.c:15 [inline]
 <IRQ> [   24.190280]  [<ffffffff81d941c9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff8142f3c1>] panic+0x1bc/0x3a8 kernel/panic.c:179
 [<ffffffff81131144>] __warn+0x1c4/0x1e0 kernel/panic.c:542
 [<ffffffff811313ac>] warn_slowpath_null+0x2c/0x40 kernel/panic.c:585
 [<ffffffff832ebc36>] inet_sock_destruct+0x5f6/0x7b0 net/ipv4/af_inet.c:167
 [<ffffffff835849d2>] l2tp_tunnel_destruct+0x352/0x5a0 net/l2tp/l2tp_core.c:1329
 [<ffffffff82ee5033>] __sk_destruct+0x53/0x570 net/core/sock.c:1428
 [<ffffffff812930f8>] __rcu_reclaim kernel/rcu/rcu.h:118 [inline]
 [<ffffffff812930f8>] rcu_do_batch kernel/rcu/tree.c:2789 [inline]
 [<ffffffff812930f8>] invoke_rcu_callbacks kernel/rcu/tree.c:3053 [inline]
 [<ffffffff812930f8>] __rcu_process_callbacks kernel/rcu/tree.c:3020 [inline]
 [<ffffffff812930f8>] rcu_process_callbacks+0x898/0x1300 kernel/rcu/tree.c:3037
 [<ffffffff838b9846>] __do_softirq+0x206/0x951 kernel/softirq.c:284
 [<ffffffff81146bc5>] invoke_softirq kernel/softirq.c:364 [inline]
 [<ffffffff81146bc5>] irq_exit+0x165/0x190 kernel/softirq.c:405
 [<ffffffff838b845b>] exiting_irq arch/x86/include/asm/apic.h:659 [inline]
 [<ffffffff838b845b>] smp_apic_timer_interrupt+0x7b/0xa0 arch/x86/kernel/apic/apic.c:960
 [<ffffffff838b46e0>] apic_timer_interrupt+0xa0/0xb0 arch/x86/entry/entry_64.S:741
 <EOI> [   24.265869]  [<ffffffff838b1886>] ? native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:53
 [<ffffffff838b0eb5>] arch_safe_halt arch/x86/include/asm/paravirt.h:103 [inline]
 [<ffffffff838b0eb5>] default_idle+0x55/0x360 arch/x86/kernel/process.c:295
 [<ffffffff8106bc9a>] arch_cpu_idle+0xa/0x10 arch/x86/kernel/process.c:286
 [<ffffffff838b1cc6>] default_idle_call+0x36/0x60 kernel/sched/idle.c:97
 [<ffffffff81226500>] cpuidle_idle_call kernel/sched/idle.c:155 [inline]
 [<ffffffff81226500>] cpu_idle_loop kernel/sched/idle.c:248 [inline]
 [<ffffffff81226500>] cpu_startup_entry+0x2b0/0x380 kernel/sched/idle.c:303
 [<ffffffff810afc93>] start_secondary+0x303/0x3e0 arch/x86/kernel/smpboot.c:254
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..