Re: [PATCH mm-unstable v3 3/5] mm/khugepaged: define KHUGEPAGED_MAX_PTES_LIMIT as HPAGE_PMD_NR - 1

[Lorenzo Stoakes (Oracle)]

On Wed, Mar 11, 2026 at 03:13:13PM -0600, Nico Pache wrote:
> The value (HPAGE_PMD_NR - 1) is used often in the khugepaged code to
> signify the limit of the max_ptes_* values. Add a define for this to
> increase code readability and reuse.
>
> Acked-by: Pedro Falcato <pfalcato@xxxxxxx>
> Acked-by: David Hildenbrand (Arm) <david@xxxxxxxxxx>
> Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
> Reviewed-by: Zi Yan <ziy@xxxxxxxxxx>
> Signed-off-by: Nico Pache <npache@xxxxxxxxxx>

Hm didn't I suggest this? Or actually I can't remember :P

Anyway LGTM, so:

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

> ---
>  mm/khugepaged.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index d3bdec4ec61b..db77ab5b315e 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -89,6 +89,7 @@ static DECLARE_WAIT_QUEUE_HEAD(khugepaged_wait);
>   *
>   * Note that these are only respected if collapse was initiated by khugepaged.
>   */
> +#define KHUGEPAGED_MAX_PTES_LIMIT (HPAGE_PMD_NR - 1)
>  unsigned int khugepaged_max_ptes_none __read_mostly;
>  static unsigned int khugepaged_max_ptes_swap __read_mostly;
>  static unsigned int khugepaged_max_ptes_shared __read_mostly;
> @@ -259,7 +260,7 @@ static ssize_t max_ptes_none_store(struct kobject *kobj,
>  	unsigned long max_ptes_none;
>
>  	err = kstrtoul(buf, 10, &max_ptes_none);
> -	if (err || max_ptes_none > HPAGE_PMD_NR - 1)
> +	if (err || max_ptes_none > KHUGEPAGED_MAX_PTES_LIMIT)
>  		return -EINVAL;
>
>  	khugepaged_max_ptes_none = max_ptes_none;
> @@ -284,7 +285,7 @@ static ssize_t max_ptes_swap_store(struct kobject *kobj,
>  	unsigned long max_ptes_swap;
>
>  	err  = kstrtoul(buf, 10, &max_ptes_swap);
> -	if (err || max_ptes_swap > HPAGE_PMD_NR - 1)
> +	if (err || max_ptes_swap > KHUGEPAGED_MAX_PTES_LIMIT)
>  		return -EINVAL;
>
>  	khugepaged_max_ptes_swap = max_ptes_swap;
> @@ -310,7 +311,7 @@ static ssize_t max_ptes_shared_store(struct kobject *kobj,
>  	unsigned long max_ptes_shared;
>
>  	err  = kstrtoul(buf, 10, &max_ptes_shared);
> -	if (err || max_ptes_shared > HPAGE_PMD_NR - 1)
> +	if (err || max_ptes_shared > KHUGEPAGED_MAX_PTES_LIMIT)
>  		return -EINVAL;
>
>  	khugepaged_max_ptes_shared = max_ptes_shared;
> @@ -382,7 +383,7 @@ int __init khugepaged_init(void)
>  		return -ENOMEM;
>
>  	khugepaged_pages_to_scan = HPAGE_PMD_NR * 8;
> -	khugepaged_max_ptes_none = HPAGE_PMD_NR - 1;
> +	khugepaged_max_ptes_none = KHUGEPAGED_MAX_PTES_LIMIT;
>  	khugepaged_max_ptes_swap = HPAGE_PMD_NR / 8;
>  	khugepaged_max_ptes_shared = HPAGE_PMD_NR / 2;
>
> --
> 2.53.0
>