unregister_netdevice: waiting for bridge0 to become free

[syzbot]

Hello,

syzbot hit the following crash on net-next commit
0565de29cbd65b378147d36f9642f93a046240dc (Wed Apr 18 03:41:18 2018 +0000)
Merge branch 'ipv6-Separate-data-structures-for-FIB-and-data-path'
syzbot dashboard link:
https://syzkaller.appspot.com/bug?extid=47d81cf381dfdd73bab9

Unfortunately, I don't have any reproducer for this crash yet.
Raw console output:
https://syzkaller.appspot.com/x/log.txt?id=4541517133774848
Kernel config:
https://syzkaller.appspot.com/x/.config?id=-5947642240294114534
compiler: gcc (GCC) 8.0.1 20180413 (experimental)
CC: []

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+47d81c...@syzkaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for
details.
If you forward the report, please keep this part and the footer.

device bridge_slave_1 left promiscuous mode
bridge0: port 2(bridge_slave_1) entered disabled state
device bridge_slave_0 left promiscuous mode
bridge0: port 1(bridge_slave_0) entered disabled state
unregister_netdevice: waiting for bridge0 to become free. Usage count = 3


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[Dmitry Vyukov]

superceded by "unregister_netdevice: waiting for DEV to become free"

#syz invalid

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