Re: kernel BUG at fs/buffer.c:LINE!

[syzbot]

syzbot has bisected this bug to:

commit 5db470e229e22b7eda6e23b5566e532c96fb5bc3
Author: Jaegeuk Kim <jaegeuk@xxxxxxxxxx>
Date:   Thu Jan 10 03:17:14 2019 +0000

    loop: drop caches if offset or block_size are changed

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=13f3ca8ee00000
start commit:   2187f215 Merge tag 'for-5.5-rc2-tag' of git://git.kernel.o..
git tree:       upstream
final crash:    https://syzkaller.appspot.com/x/report.txt?x=100bca8ee00000
console output: https://syzkaller.appspot.com/x/log.txt?x=17f3ca8ee00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=dcf10bf83926432a
dashboard link: https://syzkaller.appspot.com/bug?extid=cfed5b56649bddf80d6e
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1171ba8ee00000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=107440aee00000

Reported-by: syzbot+cfed5b56649bddf80d6e@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 5db470e229e2 ("loop: drop caches if offset or block_size are  
changed")

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