Re: WARNING: suspicious RCU usage in io_init_identity

[Dmitry Vyukov]

On Fri, Oct 16, 2020 at 5:05 PM Jens Axboe <axboe@xxxxxxxxx> wrote:
>
> On 10/16/20 9:02 AM, Qian Cai wrote:
> > On Fri, 2020-10-16 at 01:12 -0700, syzbot wrote:
> >> Hello,
> >>
> >> syzbot found the following issue on:
> >>
> >> HEAD commit:    b2926c10 Add linux-next specific files for 20201016
> >> git tree:       linux-next
> >> console output: https://syzkaller.appspot.com/x/log.txt?x=12fc877f900000
> >> kernel config:  https://syzkaller.appspot.com/x/.config?x=6160209582f55fb1
> >> dashboard link: https://syzkaller.appspot.com/bug?extid=4596e1fcf98efa7d1745
> >> compiler:       gcc (GCC) 10.1.0-syz 20200507
> >>
> >> Unfortunately, I don't have any reproducer for this issue yet.
> >>
> >> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> >> Reported-by: syzbot+4596e1fcf98efa7d1745@xxxxxxxxxxxxxxxxxxxxxxxxx
> >>
> >> =============================
> >> WARNING: suspicious RCU usage
> >> 5.9.0-next-20201016-syzkaller #0 Not tainted
> >> -----------------------------
> >> include/linux/cgroup.h:494 suspicious rcu_dereference_check() usage!
> >
> > Introduced by the linux-next commits:
> >
> > 07950f53f85b ("io_uring: COW io_identity on mismatch")
> >
> > Can't find the patchset was posted anywhere. Anyway, this should fix it?
>
> It's just in testing... I already folded in this change.

Now that it's in linux-next we can close this report:

#syz fix: io_uring: COW io_identity on mismatch