Re: [PATCH v5 14/15] mm/kasan: add document into kernel-parameters.txt

Samuel Holland
2026-03-17T03:50:07Z

On 2026-03-16 10:36 PM, Baoquan He wrote:
> On 03/12/26 at 07:53am, Samuel Holland wrote:
>> Hi Baoquan,
>>
>> On 2026-02-25 2:14 AM, Baoquan He wrote:
>>> And also remove the relevant description in dev-tools/kasan.rst
>>> which is hw_tags specificially.
>>>
>>> Signed-off-by: Baoquan He <bhe@redhat.com>
>>> ---
>>> Documentation/admin-guide/kernel-parameters.txt | 4 ++++
>>> Documentation/dev-tools/kasan.rst | 2 --
>>> 2 files changed, 4 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>>> index cb850e5290c2..e0115fad9e60 100644
>>> --- a/Documentation/admin-guide/kernel-parameters.txt
>>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>>> @@ -2899,6 +2899,10 @@ Kernel parameters
>>> js= [HW,JOY] Analog joystick
>>> See Documentation/input/joydev/joystick.rst.
>>>
>>> + kasan= [KNL] controls whether KASAN is enabled.
>>> + Format: off | on
>>> + default: on
>>> +
>>> kasan_multi_shot
>>> [KNL] Enforce KASAN (Kernel Address Sanitizer) to print
>>> report on every invalid memory access. Without this
>>> diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
>>> index a034700da7c4..eaae83fcb5e4 100644
>>> --- a/Documentation/dev-tools/kasan.rst
>>> +++ b/Documentation/dev-tools/kasan.rst
>>> @@ -129,8 +129,6 @@ Hardware Tag-Based KASAN mode is intended for use in production as a security
>>> mitigation. Therefore, it supports additional boot parameters that allow
>>> disabling KASAN altogether or controlling its features:
>>
>> The sentence above is now incorrect as well. I would recommend documenting the
>> parameter earlier in the "Boot parameters" section instead of removing it from
>> this document entirely.
>
> Good catch and the suggestion is good to me. Thanks.
>
> Is below change OK to you?
>
>
> From 317be48b9c1bf9d33b8d8fff5e401e3155531d81 Mon Sep 17 00:00:00 2001
> From: Baoquan He <bhe@redhat.com>
> Date: Tue, 17 Mar 2026 11:28:39 +0800
> Subject: [PATCH] mm/kasan: adjust documentation

I'd suggest something a bit more specific, maybe like "mm/kasan: document kasan=
for all modes".

> Content-type: text/plain
>
> To reflect the change of kasan=on|off.
>
> Signed-off-by: Baoquan He <bhe@redhat.com>
> ---
> Documentation/dev-tools/kasan.rst | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/Documentation/dev-tools/kasan.rst b/Documentation/dev-tools/kasan.rst
> index a034700da7c4..8e65bc04dbcd 100644
> --- a/Documentation/dev-tools/kasan.rst
> +++ b/Documentation/dev-tools/kasan.rst
> @@ -103,6 +103,9 @@ Boot parameters
> KASAN is affected by the generic ``panic_on_warn`` command line parameter.
> When it is enabled, KASAN panics the kernel after printing a bug report.
>
> +The generic ``kasan=off`` or ``=on`` command line parameter controls
> +whether KASAN is enabled (default: ``on``).
> +

This is in the middle of paragraphs describing the fault reporting options. I'd
suggest to move it to the beginning of the section.

With those fixes, you can add

Reviewed-by: Samuel Holland <samuel.holland@sifive.com>

> By default, KASAN prints a bug report only for the first invalid memory access.
> With ``kasan_multi_shot``, KASAN prints a report on every invalid access. This
> effectively disables ``panic_on_warn`` for KASAN reports.
> @@ -127,9 +130,7 @@ modes below) support altering stack trace collection behavior:
>
> Hardware Tag-Based KASAN mode is intended for use in production as a security
> mitigation. Therefore, it supports additional boot parameters that allow
> -disabling KASAN altogether or controlling its features:
> -
> -- ``kasan=off`` or ``=on`` controls whether KASAN is enabled (default: ``on``).
> +controlling its features:
>
> - ``kasan.mode=sync``, ``=async`` or ``=asymm`` controls whether KASAN
> is configured in synchronous, asynchronous or asymmetric mode of