Re: [syzbot] WARNING in __percpu_ref_exit (2)

[Dmitry Vyukov]

On Mon, 13 Sept 2021 at 11:22, syzbot
<syzbot+d6218cb2fae0b2411e9d@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
>
> syzbot suspects this issue was fixed by commit:
>
> commit 43016d02cf6e46edfc4696452251d34bba0c0435
> Author: Florian Westphal <fw@xxxxxxxxx>
> Date:   Mon May 3 11:51:15 2021 +0000
>
>     netfilter: arptables: use pernet ops struct during unregister
>
> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=10acd273300000
> start commit:   c98ff1d013d2 Merge tag 'scsi-fixes' of git://git.kernel.or..
> git tree:       upstream
> kernel config:  https://syzkaller.appspot.com/x/.config?x=1c70e618af4c2e92
> dashboard link: https://syzkaller.appspot.com/bug?extid=d6218cb2fae0b2411e9d
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=145cb2b6d00000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=157b72b1d00000
>
> If the result looks correct, please mark the issue as fixed by replying with:
>
> #syz fix: netfilter: arptables: use pernet ops struct during unregister
>
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection

I guess this is a wrong commit and it was fixed by something in io_uring.
Searching for refcount fixes I see
a298232ee6b9a1d5d732aa497ff8be0d45b5bd82 "io_uring: fix link timeout
refs".
Pavel, does it look right to you?