linux-kernel - Re: [PATCH 1/2] module: Override -EEXISTS module return

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Message-ID: <k4oueia5w5hjzusdcmhvimvpjcpjq4blhwc37y2w2luagdywaq@vrnknn6gbydo>
Date: Sun, 2 Nov 2025 13:23:53 -0500
From: Aaron Tomlin <atomlin@...mlin.com>
To: Lucas De Marchi <lucas.demarchi@...el.com>
Cc: linux-modules@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Petr Pavlu <petr.pavlu@...e.com>
Subject: Re: [PATCH 1/2] module: Override -EEXISTS module return

On Mon, Oct 13, 2025 at 09:26:23AM -0700, Lucas De Marchi wrote:
> The -EEXIST errno is reserved by the module loading functionality. When
> userspace calls [f]init_module(), it expects a -EEXIST to mean that the
> module is already loaded in the kernel. If module_init() returns it,
> that is not true anymore.
> 
> Add a warning and override the return code to workaround modules
> currently returning the wrong code. It's expected that they eventually
> migrate to a better suited error.
> 
> Closes: https://lore.kernel.org/all/aKLzsAX14ybEjHfJ@orbyte.nwl.cc/
> Signed-off-by: Lucas De Marchi <lucas.demarchi@...el.com>
> ---
>  kernel/module/main.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/kernel/module/main.c b/kernel/module/main.c
> index c66b261849362..74ff87b13c517 100644
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -3038,6 +3038,11 @@ static noinline int do_init_module(struct module *mod)
>  	if (mod->init != NULL)
>  		ret = do_one_initcall(mod->init);
>  	if (ret < 0) {
> +		if (ret == -EEXIST) {
> +			pr_warn("%s: init suspiciously returned -EEXIST: Overriding with -EBUSY\n",
> +				mod->name);
> +			ret = -EBUSY;
> +		}
>  		goto fail_free_freeinit;
>  	}
>  	if (ret > 0) {
> 
> -- 
> 2.51.0
> 
> 

Reviewed-by: Aaron Tomlin <atomlin@...mlin.com>

-- 
Aaron Tomlin