------------[ cut here ]------------
WARNING: CPU: 0 PID: 31708 at net/xfrm/xfrm_state.c:2192 xfrm_state_fini+0x2a0/0x340 net/xfrm/xfrm_state.c:2192
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 31708 Comm: kworker/u4:0 Not tainted 4.9.192+ #0
Workqueue: netns cleanup_net
 ffff8801cf83f900 ffffffff81b67081 0000000000000000 ffffffff82a3b340
 00000000ffffffff 0000000000000000 0000000000000009 ffff8801cf83f9e0
 ffffffff813fefda 0000000041b58ab3 ffffffff82e32ec5 ffffffff813fee01
Call Trace:
 [<00000000ddb42f13>] __dump_stack lib/dump_stack.c:15 [inline]
 [<00000000ddb42f13>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<00000000f2687e27>] panic+0x1d9/0x3bd kernel/panic.c:180
 [<0000000041233d8c>] __warn.cold+0x2f/0x2f kernel/panic.c:546
 [<00000000ae22f468>] warn_slowpath_null+0x2d/0x40 kernel/panic.c:589
 [<0000000099ffe341>] xfrm_state_fini+0x2a0/0x340 net/xfrm/xfrm_state.c:2192
 [<0000000092f36e68>] xfrm_net_exit+0x2e/0x40 net/xfrm/xfrm_policy.c:3122
 [<000000006af6c5ca>] ops_exit_list.isra.0+0xb0/0x160 net/core/net_namespace.c:136
 [<000000003c408af9>] cleanup_net+0x3d6/0x8a0 net/core/net_namespace.c:474
 [<00000000589e8ab1>] process_one_work+0x88b/0x1600 kernel/workqueue.c:2114
 [<00000000f7eb5eea>] worker_thread+0x5df/0x11d0 kernel/workqueue.c:2251
 [<000000003e78fdce>] kthread+0x278/0x310 kernel/kthread.c:211
 [<00000000e17cf189>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:375
Kernel Offset: disabled
Rebooting in 86400 seconds..