WARNING: locking bug in inet_autobind

[syzbot]

syzbot has bisected this bug to:

commit c0d9271ecbd891cdeb0fad1edcdd99ee717a655f
Author: Yong Zhao <Yong.Zhao at amd.com>
Date:   Fri Feb 1 23:36:21 2019 +0000

     drm/amdgpu: Delete user queue doorbell variables

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1433ece4a00000
start commit:   f49aa1de Merge tag 'for-5.2-rc1-tag' of git://git.kernel.o..
git tree:       net-next
final crash:    https://syzkaller.appspot.com/x/report.txt?x=1633ece4a00000
console output: https://syzkaller.appspot.com/x/log.txt?x=1233ece4a00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=fc045131472947d7
dashboard link: https://syzkaller.appspot.com/bug?extid=94cc2a66fc228b23f360
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=163731f8a00000

Reported-by: syzbot+94cc2a66fc228b23f360 at syzkaller.appspotmail.com
Fixes: c0d9271ecbd8 ("drm/amdgpu: Delete user queue doorbell variables")

For information about bisection process see: https://goo.gl/tpsmEJ#bisection