WARNING in xfrm_policy_fini

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    3eb2ce825ea1 Linux 4.16-rc7
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1132989b800000
kernel config:  https://syzkaller.appspot.com/x/.config?x=8addcf4530d93e53
dashboard link: https://syzkaller.appspot.com/bug?extid=9bce6db6c82f06b85d8b
compiler:       gcc (GCC) 7.1.1 20170620

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+9bce6db6c82f06b85d8b@xxxxxxxxxxxxxxxxxxxxxxxxx

bond0 (unregistering): Released all slaves
WARNING: CPU: 1 PID: 7312 at net/xfrm/xfrm_policy.c:2925  
xfrm_policy_fini+0x414/0x560 net/xfrm/xfrm_policy.c:2925
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 7312 Comm: kworker/u4:7 Not tainted 4.16.0-rc7+ #3
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: netns cleanup_net
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x194/0x24d lib/dump_stack.c:53
 panic+0x1e4/0x41c kernel/panic.c:183
 __warn+0x1dc/0x200 kernel/panic.c:547
 report_bug+0x1f4/0x2b0 lib/bug.c:186
 fixup_bug.part.11+0x37/0x80 arch/x86/kernel/traps.c:178
 fixup_bug arch/x86/kernel/traps.c:247 [inline]
 do_error_trap+0x2d7/0x3e0 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
 invalid_op+0x1b/0x40 arch/x86/entry/entry_64.S:986
RIP: 0010:xfrm_policy_fini+0x414/0x560 net/xfrm/xfrm_policy.c:2925
RSP: 0018:ffff8801b25d70d8 EFLAGS: 00010293
RAX: ffff8801b129c540 RBX: ffff8801b5608200 RCX: ffffffff8587ff74
RDX: 0000000000000000 RSI: 1ffff100362539c5 RDI: ffffffff87acabf8
RBP: ffff8801b25d7260 R08: 1ffff100364badd1 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 1ffff100364bae27
R13: ffff8801b25d7238 R14: ffff8801b56096f0 R15: ffff8801d71c5820
 xfrm_net_exit+0x1d/0x70 net/xfrm/xfrm_policy.c:2980
 ops_exit_list.isra.6+0xae/0x150 net/core/net_namespace.c:142
 cleanup_net+0x6a1/0xcb0 net/core/net_namespace.c:517
 process_one_work+0xc47/0x1bb0 kernel/workqueue.c:2113
 worker_thread+0x223/0x1990 kernel/workqueue.c:2247
 kthread+0x33c/0x400 kernel/kthread.c:238
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:406
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxxx

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with  
syzbot.