Re: [PATCH v4 2/7] mm/khugepaged: extract reference check into folio_pte_referenced() helper

[Baolin Wang <baolin.wang@linux.alibaba.com>]

On 8/11/26 8:48 PM, Nico Pache (Red Hat) wrote:
> This change deduplicates the "is this PTE/folio referenced enough to be
> considered for a collapse" condition that was repeated in both
> __collapse_huge_page_isolate() and collapse_scan_pmd(), extracting it into
> a single inline helper function.
> 
> Also move the comment and use it as the function header. While we are at
> it, updated the comment to clarify that a young pte is a recently accessed
> one.
> 
> Acked-by: Usama Arif <usama.arif@linux.dev>
> Signed-off-by: Nico Pache (Red Hat) <nico.pache@linux.dev>
> ---
>   mm/khugepaged.c | 32 ++++++++++++++++++--------------
>   1 file changed, 18 insertions(+), 14 deletions(-)
> 
> diff --git a/mm/khugepaged.c b/mm/khugepaged.c
> index 1e26ea97381a..8babd4c97db6 100644
> --- a/mm/khugepaged.c
> +++ b/mm/khugepaged.c
> @@ -672,6 +672,22 @@ static void release_pte_pages(pte_t *pte, pte_t *_pte,
>   	}
>   }
>   
> +/*
> + * folio_pte_referenced() - Check if a folio or its PTE mapping was recently used
> + *
> + * Return: true if recent access was observed through either the folio state
> + * or the current PTE mapping.
> + */
> +static inline bool folio_pte_referenced(struct folio *folio,
> +		struct vm_area_struct *vma, unsigned long addr, pte_t pteval)
> +{
> +	/* The folio was referenced previously ... */
> +	if (folio_test_young(folio) || folio_test_referenced(folio))
> +		return true;
> +	/* ... or the PTE mapping was recently used */
> +	return pte_young(pteval) || mmu_notifier_test_young(vma->vm_mm, addr);
> +}

Thanks David for asking again to move the 'cc->is_khugepaged' out of 
this helper. I also suggested this before[1]. So

Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>

[1] 
https://lore.kernel.org/all/62b2bd29-28d2-4440-a970-526dd5d5bbe0@linux.alibaba.com/