Re: [syzbot] BUG: unable to handle kernel NULL pointer dereference in f2fs_stop_discard_thread

[syzbot]

syzbot has bisected this issue to:

commit 4d67490498acb4ffcef5ba7bc44990d46e66a44c
Author: Fengnan Chang <changfengnan@xxxxxxxx>
Date:   Thu Aug 19 08:02:37 2021 +0000

    f2fs: Don't create discard thread when device doesn't support realtime discard

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=17da7522880000
start commit:   247f34f7b803 Linux 6.1-rc2
git tree:       upstream
final oops:     https://syzkaller.appspot.com/x/report.txt?x=143a7522880000
console output: https://syzkaller.appspot.com/x/log.txt?x=103a7522880000
kernel config:  https://syzkaller.appspot.com/x/.config?x=a66c6c673fb555e8
dashboard link: https://syzkaller.appspot.com/bug?extid=035a381ea1afb63f098d
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=11d92d6a880000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=12e5dbba880000

Reported-by: syzbot+035a381ea1afb63f098d@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 4d67490498ac ("f2fs: Don't create discard thread when device doesn't support realtime discard")

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