Re: WARNING: refcount bug in blk_mq_free_request (2)

[syzbot]

syzbot has bisected this bug to:

commit 12f5b93145450c750f315657ef239a314811aeeb
Author: Keith Busch <keith.busch@xxxxxxxxx>
Date:   Tue May 29 13:52:28 2018 +0000

    blk-mq: Remove generation seqeunce

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1263808c600000
start commit:   e21a712a Linux 5.3-rc3
git tree:       upstream
final crash:    https://syzkaller.appspot.com/x/report.txt?x=1163808c600000
console output: https://syzkaller.appspot.com/x/log.txt?x=1663808c600000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a4c9e9f08e9e8960
dashboard link: https://syzkaller.appspot.com/bug?extid=f4316dab9d4518b755eb
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=117a1906600000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=11aa11aa600000

Reported-by: syzbot+f4316dab9d4518b755eb@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 12f5b9314545 ("blk-mq: Remove generation seqeunce")

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