syzbot has bisected this issue to:
commit 708fa01597fa002599756bf56a96d0de1677375c
Author: Miklos Szeredi <mszeredi@xxxxxxxxxx>
Date: Mon Apr 12 10:00:37 2021 +0000
ovl: allow upperdir inside lowerdir
bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=17ad11b2680000
start commit: 3aba70aed91f Merge tag 'gpio-fixes-for-v6.6-rc3' of git://..
git tree: upstream
final oops: https://syzkaller.appspot.com/x/report.txt?x=146d11b2680000
console output: https://syzkaller.appspot.com/x/log.txt?x=106d11b2680000
kernel config: https://syzkaller.appspot.com/x/.config?x=e4ca82a1bedd37e4
dashboard link: https://syzkaller.appspot.com/bug?extid=b42fe626038981fb7bfa
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1304fba6680000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=13cec0dc680000
Reported-by: syzbot+b42fe626038981fb7bfa@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 708fa01597fa ("ovl: allow upperdir inside lowerdir")
For information about bisection process see: https://goo.gl/tpsmEJ#bisection
