WARNING: CPU: 1 PID: 1851 at net/ipv6/xfrm6_tunnel.c:345 xfrm6_tunnel_net_exit+0x2c0/0x4f0 net/ipv6/xfrm6_tunnel.c:345
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 1851 Comm: kworker/u4:4 Not tainted 4.17.0-rc4+ #40
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1b9/0x294 lib/dump_stack.c:113
 panic+0x22f/0x4de kernel/panic.c:184
 __warn.cold.8+0x163/0x1b3 kernel/panic.c:536
 report_bug+0x252/0x2d0 lib/bug.c:186
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x1de/0x490 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
RIP: 0010:xfrm6_tunnel_net_exit+0x2c0/0x4f0 net/ipv6/xfrm6_tunnel.c:345
RSP: 0018:ffff8801cec4f3d8 EFLAGS: 00010293
RAX: ffff8801cf2f8640 RBX: ffff8801aec75970 RCX: ffffffff868fefd6
RDX: 0000000000000000 RSI: ffffffff868fefe0 RDI: 0000000000000007
RBP: ffff8801cec4f4f8 R08: ffff8801cf2f8640 R09: ffffed003b5e46c2
R10: 0000000000000003 R11: 0000000000000003 R12: 0000000000000006
R13: ffffed0039d89e82 R14: ffff8801cec4f4d0 R15: ffff8801acdbb780
hfs: can't find a HFS filesystem on dev loop3
 ops_exit_list.isra.7+0xb0/0x160 net/core/net_namespace.c:152
 cleanup_net+0x51d/0xb20 net/core/net_namespace.c:523
 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:412
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..