------------[ cut here ]------------
WARNING: CPU: 1 PID: 2218 at net/xfrm/xfrm_state.c:2175 xfrm_state_fini+0x2a0/0x340 net/xfrm/xfrm_state.c:2175
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 2218 Comm: kworker/u4:5 Not tainted 4.9.131+ #50
Workqueue: netns cleanup_net
 ffff8801cb2b7940 ffffffff81b37029 ffffffff82a38c20 00000000ffffffff
 0000000000000000 0000000000000001 000000000000087f ffff8801cb2b7a00
 ffffffff813f6b25 0000000041b58ab3 ffffffff82e298d3 ffffffff813f6966
Call Trace:
 [<ffffffff81b37029>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b37029>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff813f6b25>] panic+0x1bf/0x39f kernel/panic.c:179
 [<ffffffff813f6df4>] __warn.cold.9+0xc1/0x17f kernel/panic.c:542
 [<ffffffff810dbf4c>] warn_slowpath_null+0x2c/0x40 kernel/panic.c:585
 [<ffffffff826451c0>] xfrm_state_fini+0x2a0/0x340 net/xfrm/xfrm_state.c:2175
 [<ffffffff82626dbd>] xfrm_net_exit+0x2d/0x30 net/xfrm/xfrm_policy.c:3072
 [<ffffffff822d1520>] ops_exit_list.isra.0+0xb0/0x160 net/core/net_namespace.c:136
 [<ffffffff822d4282>] cleanup_net+0x3f2/0x8b0 net/core/net_namespace.c:473
 [<ffffffff81130e81>] process_one_work+0x831/0x1530 kernel/workqueue.c:2092
 [<ffffffff81131c56>] worker_thread+0xd6/0x1140 kernel/workqueue.c:2226
 [<ffffffff811429fd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff8280399c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Kernel Offset: disabled
Rebooting in 86400 seconds..