Re: [PATCH] docs: proc: document ProtectionKey in smaps

[Lorenzo Stoakes]

On Tue, Apr 07, 2026 at 01:51:33PM +0100, Kevin Brodsky wrote:
> The ProtectionKey entry was added in v4.9; back then it was
> x86-specific, but it now lives in generic code and applies to all
> architectures supporting pkeys (currently x86, power, arm64).
>
> Time to document it: add a paragraph to proc.rst about the
> ProtectionKey entry.
>
> Reported-by: Yury Khrustalev <yury.khrustalev@xxxxxxx>
> Signed-off-by: Kevin Brodsky <kevin.brodsky@xxxxxxx>

LGTM, So:

Reviewed-by: Lorenzo Stoakes <ljs@xxxxxxxxxx>

> ---
> Cc: Jonathan Corbet <corbet@xxxxxxx>
> Cc: Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx>
> Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Lorenzo Stoakes <ljs@xxxxxxxxxx>
> Cc: Vlastimil Babka <vbabka@xxxxxxxxxx>
> Cc: David Hildenbrand <david@xxxxxxxxxx>
> Cc: Mark Rutland <mark.rutland@xxxxxxx>
> Cc: linux-fsdevel@xxxxxxxxxxxxxxx
> Cc: linux-mm@xxxxxxxxx
> ---
>  Documentation/filesystems/proc.rst | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/Documentation/filesystems/proc.rst b/Documentation/filesystems/proc.rst
> index b0c0d1b45b99..d673cad7dbe4 100644
> --- a/Documentation/filesystems/proc.rst
> +++ b/Documentation/filesystems/proc.rst
> @@ -549,6 +549,10 @@ does not take into account swapped out page of underlying shmem objects.
>  naturally aligned THP pages of any currently enabled size. 1 if true, 0
>  otherwise.
>
> +If both the kernel and the system support protection keys (pkeys),
> +"ProtectionKey" indicates the memory protection key associated with the
> +virtual memory area.
> +
>  "VmFlags" field deserves a separate description. This member represents the
>  kernel flags associated with the particular virtual memory area in two letter
>  encoded manner. The codes are the following:
> --
> 2.51.2
>