linux-kernel - Re: [PATCH bpf-next] libbpf: Ignore the modules that failed to load BTF object

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Message-ID: <CAEf4Bzbp2FYvTVz6SStj_p_ok+LLeXEAxcUiCkyWRf3wyjwi_Q@mail.gmail.com>
Date: Tue, 28 Oct 2025 11:05:14 -0700
From: Andrii Nakryiko <andrii.nakryiko@...il.com>
To: Bixuan Cui <cuibixuan@...o.com>
Cc: ast@...nel.org, daniel@...earbox.net, andrii@...nel.org, 
	martin.lau@...ux.dev, bpf@...r.kernel.org, linux-kernel@...r.kernel.org, 
	eddyz87@...il.com, song@...nel.org, yonghong.song@...ux.dev, 
	john.fastabend@...il.com, kpsingh@...nel.org, sdf@...ichev.me, 
	haoluo@...gle.com, jolsa@...nel.org
Subject: Re: [PATCH bpf-next] libbpf: Ignore the modules that failed to load
 BTF object

On Tue, Oct 28, 2025 at 6:57 AM Bixuan Cui <cuibixuan@...o.com> wrote:
>
> Register kfunc in self-developed module but run error in other modules:
>     libbpf: btf: type [164451]: referenced type [164446] is not FUNC_PROTO
>     libbpf: failed to load module [syscon_reboot_mode]'s BTF object #2: -22
>
> It is usually skipping the error does not affect the search for the next module.
>
> Then ignoring the failed modules, load the bpf process:
>     libbpf: btf: type [164451]: referenced type [164446] is not FUNC_PROTO
>     libbpf: failed to load module [syscon_reboot_mode]'s BTF object #3: -22
>     libbpf: extern (func ksym) 'bpf_kfunc': resolved to bpf_module [164442]
>     ...
>
> Signed-off-by: Bixuan Cui <cuibixuan@...o.com>
> ---
>  tools/lib/bpf/libbpf.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c
> index 711173acbcef..0fa0d89da068 100644
> --- a/tools/lib/bpf/libbpf.c
> +++ b/tools/lib/bpf/libbpf.c
> @@ -5702,7 +5702,8 @@ static int load_module_btfs(struct bpf_object *obj)
>                 if (err) {
>                         pr_warn("failed to load module [%s]'s BTF object #%d: %d\n",
>                                 name, id, err);
> -                       goto err_out;
> +                       close(fd);
> +                       continue;
>                 }

It's not an expected condition to have kernel module with corrupted
BTF, so I don't think we should be doing this.

pw-bot: cr


>
>                 err = libbpf_ensure_mem((void **)&obj->btf_modules, &obj->btf_module_cap,
> --
> 2.39.0
>