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

Vlastimil Babka (SUSE)
2026-04-07T13:00:19Z

On 4/7/26 14:51, 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@arm.com>
> Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>

Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>

> ---
> Cc: Jonathan Corbet <corbet@lwn.net>
> Cc: Shuah Khan <skhan@linuxfoundation.org>
> Cc: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Lorenzo Stoakes <ljs@kernel.org>
> Cc: Vlastimil Babka <vbabka@kernel.org>
> Cc: David Hildenbrand <david@kernel.org>
> Cc: Mark Rutland <mark.rutland@arm.com>
> Cc: linux-fsdevel@vger.kernel.org
> Cc: linux-mm@kvack.org
> ---
> 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: