Re: [PATCH v5 6/7] mm: use BIT() for change_protection() flags

[Lorenzo Stoakes (ARM)]

On Tue, Nov 10, 2026 at 10:04:45AM -0500, Gregory Price (Meta) wrote:
> The MM_CP_* flags are individual bits expressed as open-coded shifts.
> Use BIT() consistently for the complete block.
>
> No functional change intended.
>
> Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
> Link: https://lore.kernel.org/r/9b5e1573-6fd8-48a5-a274-a6e7ff83d2fe@xxxxxxxxxx
> Assisted-by: LLM
> Acked-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>
> Signed-off-by: Gregory Price (Meta) <gourry@xxxxxxxxxx>

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

> ---
>  include/linux/mm.h | 14 +++++++-------
>  1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 55817dea7307f..da22750faddbd 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -3572,21 +3572,21 @@ int get_cmdline(struct task_struct *task, char *buffer, int buflen);
>   * because something (e.g., COW, uffd-wp) blocks that from happening for all
>   * PTEs automatically in a writable mapping.
>   */
> -#define  MM_CP_TRY_CHANGE_WRITABLE	   (1UL << 0)
> +#define  MM_CP_TRY_CHANGE_WRITABLE	   BIT(0)
>  /* Whether this protection change is for NUMA hints */
> -#define  MM_CP_PROT_NUMA                   (1UL << 1)
> +#define  MM_CP_PROT_NUMA                   BIT(1)
>  /* Whether this change is for write protecting */
> -#define  MM_CP_UFFD_WP                     (1UL << 2) /* do wp */
> -#define  MM_CP_UFFD_WP_RESOLVE             (1UL << 3) /* Resolve wp */
> +#define  MM_CP_UFFD_WP                     BIT(2) /* do wp */
> +#define  MM_CP_UFFD_WP_RESOLVE             BIT(3) /* Resolve wp */
>  #define  MM_CP_UFFD_WP_ALL                 (MM_CP_UFFD_WP | \
>  					    MM_CP_UFFD_WP_RESOLVE)
>  /* Whether this change is for uffd RWP */
> -#define  MM_CP_UFFD_RWP                    (1UL << 4) /* do rwp */
> -#define  MM_CP_UFFD_RWP_RESOLVE            (1UL << 5) /* resolve rwp */
> +#define  MM_CP_UFFD_RWP                    BIT(4) /* do rwp */
> +#define  MM_CP_UFFD_RWP_RESOLVE            BIT(5) /* resolve rwp */
>  #define  MM_CP_UFFD_RWP_ALL                (MM_CP_UFFD_RWP | \
>  					    MM_CP_UFFD_RWP_RESOLVE)
>  /* Whether a MM_CP_PROT_NUMA change is for promotion only */
> -#define  MM_CP_PROT_NUMA_PROMO_ONLY        (1UL << 6)
> +#define  MM_CP_PROT_NUMA_PROMO_ONLY        BIT(6)
>
>  bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
>  			     pte_t pte);
> --
> 2.53.0-Meta
>

--
Cheers, Lorenzo