Re: [PATCH] mm: Constify arguments in default pxdp_get()

[Lorenzo Stoakes (ARM)]

On Fri, Sep 18, 2026 at 12:19:28PM +0530, Anshuman Khandual wrote:
> Generic MM default pxdp_get() helpers fetch the values contained in pgtable
> entries via READ_ONCE() without modifying them. Just make their arguments
> explicitly 'const' for some additional protection.
>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: David Hildenbrand <david@xxxxxxxxxx>
> Cc: Lorenzo Stoakes <ljs@xxxxxxxxxx>
> Cc: linux-mm@xxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>

LGTM so:

Acked-by: Lorenzo Stoakes (ARM) <ljs@xxxxxxxxxx>

> ---
> This patch applies on v7.2-rc3 and builds on many platforms. Some earlier
> discussion could be found here. Platorm implementations for these helpers
> could convert into these "const" format later if required.
>
> https://lore.kernel.org/all/yjqldpl7il6uqfoqrszaopchqthhlffssprmlqjkljvpkbpwkt@zetb5hyvllsl/
>
>  include/linux/pgtable.h | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
>
> diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
> index 2981e386da7b3..f09a91ff5833b 100644
> --- a/include/linux/pgtable.h
> +++ b/include/linux/pgtable.h
> @@ -490,35 +490,35 @@ static inline int pudp_set_access_flags(struct vm_area_struct *vma,
>  #endif
>
>  #ifndef ptep_get
> -static inline pte_t ptep_get(pte_t *ptep)
> +static inline pte_t ptep_get(const pte_t *ptep)
>  {
>  	return READ_ONCE(*ptep);
>  }
>  #endif
>
>  #ifndef pmdp_get
> -static inline pmd_t pmdp_get(pmd_t *pmdp)
> +static inline pmd_t pmdp_get(const pmd_t *pmdp)
>  {
>  	return READ_ONCE(*pmdp);
>  }
>  #endif
>
>  #ifndef pudp_get
> -static inline pud_t pudp_get(pud_t *pudp)
> +static inline pud_t pudp_get(const pud_t *pudp)
>  {
>  	return READ_ONCE(*pudp);
>  }
>  #endif
>
>  #ifndef p4dp_get
> -static inline p4d_t p4dp_get(p4d_t *p4dp)
> +static inline p4d_t p4dp_get(const p4d_t *p4dp)
>  {
>  	return READ_ONCE(*p4dp);
>  }
>  #endif
>
>  #ifndef pgdp_get
> -static inline pgd_t pgdp_get(pgd_t *pgdp)
> +static inline pgd_t pgdp_get(const pgd_t *pgdp)
>  {
>  	return READ_ONCE(*pgdp);
>  }
> --
> 2.43.0
>

--
Cheers, Lorenzo