------------[ cut here ]------------
WARNING: CPU: 1 PID: 8768 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: 1 PID: 8768 Comm: kworker/u4:13 Not tainted 4.9.191+ #0
Workqueue: netns cleanup_net
 ffff8801a7fa7900 ffffffff81b67171 0000000000000000 ffffffff82a3b340
 00000000ffffffff 0000000000000001 0000000000000009 ffff8801a7fa79e0
 ffffffff813ff0ca 0000000041b58ab3 ffffffff82e32ec5 ffffffff813feef1
Call Trace:
 [<0000000060c8e9c7>] __dump_stack lib/dump_stack.c:15 [inline]
 [<0000000060c8e9c7>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<0000000026534d3a>] panic+0x1d9/0x3bd kernel/panic.c:180
 [<00000000d82d0781>] __warn.cold+0x2f/0x2f kernel/panic.c:546
 [<00000000ffa6dd1f>] warn_slowpath_null+0x2d/0x40 kernel/panic.c:589
 [<000000006e205563>] xfrm_state_fini+0x2a0/0x340 net/xfrm/xfrm_state.c:2192
 [<0000000076a42979>] xfrm_net_exit+0x2e/0x40 net/xfrm/xfrm_policy.c:3122
 [<00000000d14ff54e>] ops_exit_list.isra.0+0xb0/0x160 net/core/net_namespace.c:136
 [<00000000d22207de>] cleanup_net+0x3d6/0x8a0 net/core/net_namespace.c:474
 [<0000000008b9a9a5>] process_one_work+0x88b/0x1600 kernel/workqueue.c:2114
 [<00000000c1045e73>] worker_thread+0x5df/0x11d0 kernel/workqueue.c:2251
 [<000000004d5f6e52>] kthread+0x278/0x310 kernel/kthread.c:211
 [<0000000088502888>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:375
Kernel Offset: disabled
Rebooting in 86400 seconds..