WARNING: CPU: 1 PID: 21 at net/xfrm/xfrm_state.c:2341 xfrm_state_fini+0x46a/0x620 net/xfrm/xfrm_state.c:2341
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 21 Comm: kworker/u4:1 Not tainted 4.16.0-rc2+ #242
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:17 [inline]
 dump_stack+0x194/0x24d lib/dump_stack.c:53
 panic+0x1e4/0x41c kernel/panic.c:183
 __warn+0x1dc/0x200 kernel/panic.c:547
 report_bug+0x211/0x2d0 lib/bug.c:184
 fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:178
 fixup_bug arch/x86/kernel/traps.c:247 [inline]
 do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
 invalid_op+0x58/0x80 arch/x86/entry/entry_64.S:957
RIP: 0010:xfrm_state_fini+0x46a/0x620 net/xfrm/xfrm_state.c:2341
RSP: 0018:ffff8801d9447150 EFLAGS: 00010293
RAX: ffff8801d9436580 RBX: ffff8801cd526200 RCX: ffffffff84e9ea7a
RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffffff86ec96b8
RBP: ffff8801d94472a8 R08: 1ffff1003b288dbd R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff1003b288e2c
R13: ffff8801d9447280 R14: 1ffff1003b288e30 R15: ffff8801cd527600
 xfrm_net_exit+0x25/0x70 net/xfrm/xfrm_policy.c:2978
 ops_exit_list.isra.6+0xae/0x150 net/core/net_namespace.c:146
 cleanup_net+0x5a3/0xbf0 net/core/net_namespace.c:539
 process_one_work+0xbbf/0x1af0 kernel/workqueue.c:2113
 worker_thread+0x223/0x1990 kernel/workqueue.c:2247
 kthread+0x33c/0x400 kernel/kthread.c:238
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:407
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..