------------[ cut here ]------------
WARNING: CPU: 1 PID: 9246 at net/xfrm/xfrm_policy.c:3057 xfrm_policy_fini+0x28b/0x320 net/xfrm/xfrm_policy.c:3057
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 9246 Comm: kworker/u4:18 Not tainted 4.9.150+ #6
Workqueue: netns cleanup_net
 ffff8801d4a7f8e8 ffffffff81b47ee1 0000000000000000 ffffffff82a39be0
 00000000ffffffff 0000000000000001 0000000000000009 ffff8801d4a7f9c8
 ffffffff813f725a 0000000041b58ab3 ffffffff82e35992 ffffffff813f7081
Call Trace:
 [<ffffffff81b47ee1>] __dump_stack lib/dump_stack.c:15 [inline]
 [<ffffffff81b47ee1>] dump_stack+0xc1/0x120 lib/dump_stack.c:51
 [<ffffffff813f725a>] panic+0x1d9/0x3bd kernel/panic.c:180
 [<ffffffff813f749b>] __warn.cold+0x2f/0x2f kernel/panic.c:546
 [<ffffffff810dae7d>] warn_slowpath_null+0x2d/0x40 kernel/panic.c:589
 [<ffffffff82638eeb>] xfrm_policy_fini+0x28b/0x320 net/xfrm/xfrm_policy.c:3057
 [<ffffffff82638fa6>] xfrm_net_exit+0x26/0x40 net/xfrm/xfrm_policy.c:3118
 [<ffffffff822e6a30>] ops_exit_list.isra.0+0xb0/0x160 net/core/net_namespace.c:136
 [<ffffffff822e97c6>] cleanup_net+0x3d6/0x8a0 net/core/net_namespace.c:473
 [<ffffffff8113001b>] process_one_work+0x88b/0x15c0 kernel/workqueue.c:2092
 [<ffffffff8113132f>] worker_thread+0x5df/0x11d0 kernel/workqueue.c:2226
 [<ffffffff81141e18>] kthread+0x278/0x310 kernel/kthread.c:211
 [<ffffffff8281639c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373
Kernel Offset: disabled
Rebooting in 86400 seconds..