WARNING in xfrm6_tunnel_net_exit (2)

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit:    2c71d338bef2 Merge tag 'powerpc-4.17-6' of git://git.kerne..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12a7bd57800000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f3b4e30da84ec1ed
dashboard link: https://syzkaller.appspot.com/bug?extid=e9aebef558e3ed673934
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
syzkaller repro:https://syzkaller.appspot.com/x/repro.syz?x=17409d57800000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+e9aebef558e3ed673934@xxxxxxxxxxxxxxxxxxxxxxxxx

bond0: Enslaving bond_slave_1 as an active interface with an up link
IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready
IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready
IPv6: ADDRCONF(NETDEV_UP): veth1_to_bond: link is not ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bond: link becomes ready
WARNING: CPU: 1 PID: 6 at net/ipv6/xfrm6_tunnel.c:348  
xfrm6_tunnel_net_exit+0x2df/0x510 net/ipv6/xfrm6_tunnel.c:348
IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bond: link becomes ready
Kernel panic - not syncing: panic_on_warn set ...

CPU: 1 PID: 6 Comm: kworker/u4:0 Not tainted 4.17.0-rc5+ #57
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bond: link becomes ready
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Workqueue: netns cleanup_net
IPv6: ADDRCONF(NETDEV_CHANGE): veth0_to_bond: link becomes ready
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x1b9/0x294 lib/dump_stack.c:113
 panic+0x22f/0x4de kernel/panic.c:184
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bond: link becomes ready
IPv6: ADDRCONF(NETDEV_CHANGE): veth1_to_bond: link becomes ready
 __warn.cold.8+0x163/0x1b3 kernel/panic.c:536
 report_bug+0x252/0x2d0 lib/bug.c:186
IPv6: ADDRCONF(NETDEV_UP): veth0_to_bond: link is not ready
 fixup_bug arch/x86/kernel/traps.c:178 [inline]
 do_error_trap+0x1de/0x490 arch/x86/kernel/traps.c:296
 do_invalid_op+0x1b/0x20 arch/x86/kernel/traps.c:315
 invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:992
RIP: 0010:xfrm6_tunnel_net_exit+0x2df/0x510 net/ipv6/xfrm6_tunnel.c:348
RSP: 0018:ffff8801d9a973d8 EFLAGS: 00010293
RAX: ffff8801d9a88180 RBX: ffff8801b6eda2b8 RCX: ffffffff868ff5f5
RDX: 0000000000000000 RSI: ffffffff868ff5ff RDI: 0000000000000007
RBP: ffff8801d9a974f8 R08: ffff8801d9a88180 R09: 0000000000000006
R10: ffff8801d9a88180 R11: 0000000000000000 R12: 00000000000000ff
R13: ffffed003b352e82 R14: ffff8801d9a974d0 R15: ffff8801b32f0700
 ops_exit_list.isra.7+0xb0/0x160 net/core/net_namespace.c:152
 cleanup_net+0x51d/0xb20 net/core/net_namespace.c:523
 process_one_work+0xc1e/0x1b50 kernel/workqueue.c:2145
 worker_thread+0x1cc/0x1440 kernel/workqueue.c:2279
 kthread+0x345/0x410 kernel/kthread.c:240
 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:412
Dumping ftrace buffer:
   (ftrace buffer empty)
Kernel Offset: disabled
Rebooting in 86400 seconds..


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