linux-kernel - Re: [PATCH] kasan, doc: note kasan.fault=panic_on

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Message-ID: <CA+fCnZe4cetv53bGM0cOxLGB+ZDiNU7eeSb2LKNkO2j4xCPkYQ@mail.gmail.com>
Date:   Tue, 20 Jun 2023 19:19:06 +0200
From:   Andrey Konovalov <andreyknvl@...il.com>
To:     Marco Elver <elver@...gle.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Taras Madan <tarasmadan@...gle.com>,
        Aleksandr Nogikh <nogikh@...gle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Jonathan Corbet <corbet@....net>, kasan-dev@...glegroups.com,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Catalin Marinas <catalin.marinas@....com>
Subject: Re: [PATCH] kasan, doc: note kasan.fault=panic_on_write behaviour for
 async modes

On Tue, Jun 20, 2023 at 7:17 PM Marco Elver <elver@...gle.com> wrote:
>
> Note the behaviour of kasan.fault=panic_on_write for async modes, since
> all asynchronous faults will result in panic (even if they are reads).
>
> Fixes: 452c03fdbed0 ("kasan: add support for kasan.fault=panic_on_write")
> Signed-off-by: Marco Elver <elver@...gle.com>
> ---
>  Documentation/dev-tools/kasan.rst | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
> index 7f37a46af574..f4acf9c2e90f 100644
> --- a/Documentation/dev-tools/kasan.rst
> +++ b/Documentation/dev-tools/kasan.rst
> @@ -110,7 +110,9 @@ parameter can be used to control panic and reporting behaviour:
>  - ``kasan.fault=report``, ``=panic``, or ``=panic_on_write`` controls whether
>    to only print a KASAN report, panic the kernel, or panic the kernel on
>    invalid writes only (default: ``report``). The panic happens even if
> -  ``kasan_multi_shot`` is enabled.
> +  ``kasan_multi_shot`` is enabled. Note that when using asynchronous mode of
> +  Hardware Tag-Based KASAN, ``kasan.fault=panic_on_write`` always panics on
> +  asynchronously checked accesses (including reads).
>
>  Software and Hardware Tag-Based KASAN modes (see the section about various
>  modes below) support altering stack trace collection behavior:
> --
> 2.41.0.185.g7c58973941-goog
>

Reviewed-by: Andrey Konovalov <andreyknvl@...il.com>