------------[ cut here ]------------
WARNING: CPU: 1 PID: 9673 at net/xfrm/xfrm_policy.c:3057 xfrm_policy_fini+0x26f/0x2f0 net/xfrm/xfrm_policy.c:3057
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 9673 Comm: kworker/u4:24 Not tainted 4.9.146+ #83
Workqueue: netns cleanup_net
 ffff88018d91f928 ffffffff81b43aa9 ffffffff82a39060 00000000ffffffff
 ffffffff82cb7c00 0000000000000001 0000000000000009 ffff88018d91f9e8
 ffffffff813f7605 0000000041b58ab3 ffffffff82e2aab3 ffffffff813f7446
Call Trace:
 [<ffffffff81b43aa9>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b43aa9>] dump_stack+0xc1/0x128 lib/dump_stack.c:51
 [<ffffffff813f7605>] panic+0x1bf/0x39f kernel/panic.c:179
 [<ffffffff813f7842>] __warn.cold.8+0x2f/0x2f kernel/panic.c:542
 [<ffffffff810dc0bc>] warn_slowpath_null+0x2c/0x40 kernel/panic.c:585
 [<ffffffff8263bf2f>] xfrm_policy_fini+0x26f/0x2f0 net/xfrm/xfrm_policy.c:3057
 [<ffffffff8263bfd5>] xfrm_net_exit+0x25/0x30 net/xfrm/xfrm_policy.c:3118
 [<ffffffff822e5de0>] ops_exit_list.isra.0+0xb0/0x160 net/core/net_namespace.c:136
 [<ffffffff822e8b42>] cleanup_net+0x3f2/0x8b0 net/core/net_namespace.c:473
 [<ffffffff81131091>] process_one_work+0x831/0x15f0 kernel/workqueue.c:2092
 [<ffffffff81131f26>] worker_thread+0xd6/0x1140 kernel/workqueue.c:2226
 [<ffffffff81142ccd>] kthread+0x26d/0x300 kernel/kthread.c:211
 [<ffffffff8281a55c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Kernel Offset: disabled
Rebooting in 86400 seconds..