Re: [syzbot] [cgroups?] possible deadlock in cgroup_free

[syzbot]

syzbot has bisected this issue to:

commit 2d25a889601d2fbc87ec79b30ea315820f874b78
Author: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Date:   Sun Sep 17 11:24:21 2023 +0000

    ptrace: Convert ptrace_attach() to use lock guards

bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=130edb3f680000
start commit:   f31817cbcf48 Add linux-next specific files for 20231116
git tree:       linux-next
final oops:     https://syzkaller.appspot.com/x/report.txt?x=108edb3f680000
console output: https://syzkaller.appspot.com/x/log.txt?x=170edb3f680000
kernel config:  https://syzkaller.appspot.com/x/.config?x=f59345f1d0a928c
dashboard link: https://syzkaller.appspot.com/bug?extid=cef555184e66963dabc2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=13fd7920e80000
C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17d80920e80000

Reported-by: syzbot+cef555184e66963dabc2@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: 2d25a889601d ("ptrace: Convert ptrace_attach() to use lock guards")

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