linux-kernel - Re: [PATCH v4 4/4] selftest: Taint kernel when test module loaded

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Message-ID: <Yr92OngNsEOxszUA@bombadil.infradead.org>
Date:   Fri, 1 Jul 2022 15:33:30 -0700
From:   Luis Chamberlain <mcgrof@...nel.org>
To:     David Gow <davidgow@...gle.com>
Cc:     Brendan Higgins <brendanhiggins@...gle.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Jonathan Corbet <corbet@....net>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Kees Cook <keescook@...omium.org>,
        Shuah Khan <skhan@...uxfoundation.org>,
        Greg KH <gregkh@...uxfoundation.org>,
        Masahiro Yamada <masahiroy@...nel.org>,
        "Guilherme G . Piccoli" <gpiccoli@...lia.com>,
        Sebastian Reichel <sre@...nel.org>,
        John Ogness <john.ogness@...utronix.de>,
        Joe Fradley <joefradley@...gle.com>,
        Daniel Latypov <dlatypov@...gle.com>,
        kunit-dev@...glegroups.com, linux-kselftest@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Lucas De Marchi <lucas.demarchi@...el.com>,
        Aaron Tomlin <atomlin@...hat.com>,
        linux-fsdevel@...r.kernel.org, linux-block@...r.kernel.org,
        Michal Marek <michal.lkml@...kovi.net>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-kbuild@...r.kernel.org
Subject: Re: [PATCH v4 4/4] selftest: Taint kernel when test module loaded

On Fri, Jul 01, 2022 at 04:47:44PM +0800, David Gow wrote:
> Make any kselftest test module (using the kselftest_module framework)
> taint the kernel with TAINT_TEST on module load.
> 
> Note that several selftests use kernel modules which are not based on
> the kselftest_module framework, and so will not automatically taint the
> kernel.
> 
> This can be done in two ways:
> - Moving the module to the tools/testing directory. All modules under
>   this directory will taint the kernel.
> - Adding the 'test' module property with:
>   MODULE_INFO(test, "Y")

This just needs to be documented somewhere other than a commit log.
Otherwise I am not sure how we can be sure it will catch on.

> Similarly, selftests which do not load modules into the kernel generally
> should not taint the kernel (or possibly should only do so on failure),
> as it's assumed that testing from user-space should be safe. Regardless,
> they can write to /proc/sys/kernel/tainted if required.
> 
> Signed-off-by: David Gow <davidgow@...gle.com>

Looks good otherwise!

Reviewed-by: Luis Chamberlain <mcgrof@...nel.org>

Do we want this to go through selftest / kunit / modules tree?
Happy for it to through any. I can't predict a conflict.

  Luis