Re: [BUG? liburing] io_uring_register_files_update with liburing 2.0 on 5.13.17

[Victor Stewart <v@nametag.social>]

On Sun, Sep 19, 2021 at 12:40 AM Jens Axboe <axboe@kernel.dk> wrote:
>
> On 9/18/21 5:37 PM, Jens Axboe wrote:
> >> and it failed with the same as before...
> >>
> >> io_uring_register(13, IORING_REGISTER_FILES, [-1, -1, -1, 3, 4, 5, 6, 7, 8,
> >> 9, 10, 11, 12, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
> >> -1, -1, -1, -1,
> >> -1, ...], 32768) = -1 EMFILE (Too many open files)
> >>
> >> if you want i can debug it for you tomorrow? (in london)
> >
> > Nah that's fine, I think it's just because you have other files opened
> > too. We bump the cur limit _to_ 'nr', but that leaves no room for anyone
> > else. Would be my guess. It works fine for the test case I ran here, but
> > your case may be different. Does it work if you just make it:
> >
> > rlim.rlim_cur += nr;
> >
> > instead?
>
> Specifically, just something like the below incremental. If rlim_cur
> _seems_ big enough, leave it alone. If not, add the amount we need to
> cur. And don't do any error checking here, let's leave failure to the
> kernel.
>
> diff --git a/src/register.c b/src/register.c
> index bab42d0..7597ec1 100644
> --- a/src/register.c
> +++ b/src/register.c
> @@ -126,9 +126,7 @@ static int bump_rlimit_nofile(unsigned nr)
>         if (getrlimit(RLIMIT_NOFILE, &rlim) < 0)
>                 return -errno;
>         if (rlim.rlim_cur < nr) {
> -               if (nr > rlim.rlim_max)
> -                       return -EMFILE;
> -               rlim.rlim_cur = nr;
> +               rlim.rlim_cur += nr;
>                 setrlimit(RLIMIT_NOFILE, &rlim);
>         }
>

i just tried this patch and same failure. if you intend for this to remain
in the code i can debug what's going on?

>
> --
> Jens Axboe
>