Re: general protection fault in __x86_indirect_thunk_rbx

[syzbot]

syzbot has bisected this bug to:

commit dee160df820de41ff2f59a715643680822a0ab06
Author: NeilBrown <neilb@xxxxxxxx>
Date:   Mon Nov 5 01:30:47 2018 +0000

    locks: use properly initialized file_lock when unlocking.

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=13f39fd7200000
start commit:   dee160df locks: use properly initialized file_lock when un..
git tree:       linux-next
final crash:    https://syzkaller.appspot.com/x/report.txt?x=100b9fd7200000
console output: https://syzkaller.appspot.com/x/log.txt?x=17f39fd7200000
kernel config:  https://syzkaller.appspot.com/x/.config?x=caa433e1c8778437
dashboard link: https://syzkaller.appspot.com/bug?extid=83e12cf81d2c14842146
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=15bd9447400000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=1121d82b400000

Reported-by: syzbot+83e12cf81d2c14842146@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: dee160df ("locks: use properly initialized file_lock when  
unlocking.")