linux-kernel - Re: [PATCH v13 mm-new 05/16] khugepaged: introduce is_mthp

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Message-ID: <e01ef904-38b1-4c3b-8bad-cebdb4d0117c@lucifer.local>
Date: Thu, 8 Jan 2026 16:01:41 +0000
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Nico Pache <npache@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
        linux-mm@...ck.org, linux-doc@...r.kernel.org, david@...hat.com,
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Subject: Re: [PATCH v13 mm-new 05/16] khugepaged: introduce is_mthp_order
 helper

On Mon, Dec 01, 2025 at 10:46:16AM -0700, Nico Pache wrote:
> In order to add mTHP support, we will often be checking if a given order
> is a mTHP or PMD order. Lets create a simple helper function to keep the
> code clean and readable.
>
> Suggested-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> Signed-off-by: Nico Pache <npache@...hat.com>

Notwithstanding what Zi said re: using elsewhere (please do :), LGTM so:

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>

> ---
>  mm/khugepaged.c | 9 +++++++--
>  1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 8599c7fa112e..9c041141b2e3 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -338,6 +338,11 @@ static bool pte_none_or_zero(pte_t pte)
>  	return pte_present(pte) && is_zero_pfn(pte_pfn(pte));
>  }
>
> +static bool is_mthp_order(unsigned int order)
> +{
> +	return order != HPAGE_PMD_ORDER;
> +}
> +
>  int hugepage_madvise(struct vm_area_struct *vma,
>  		     vm_flags_t *vm_flags, int advice)
>  {
> @@ -1071,13 +1076,13 @@ static int alloc_charge_folio(struct folio **foliop, struct mm_struct *mm,
>  	folio = __folio_alloc(gfp, order, node, &cc->alloc_nmask);
>  	if (!folio) {
>  		*foliop = NULL;
> -		if (order == HPAGE_PMD_ORDER)
> +		if (!is_mthp_order(order))
>  			count_vm_event(THP_COLLAPSE_ALLOC_FAILED);
>  		count_mthp_stat(order, MTHP_STAT_COLLAPSE_ALLOC_FAILED);
>  		return SCAN_ALLOC_HUGE_PAGE_FAIL;
>  	}
>
> -	if (order == HPAGE_PMD_ORDER)
> +	if (!is_mthp_order(order))
>  		count_vm_event(THP_COLLAPSE_ALLOC);
>  	count_mthp_stat(order, MTHP_STAT_COLLAPSE_ALLOC);
>
> --
> 2.51.1
>