Re: [PATCH v3 10/13] mm/huge_memory: separate out the folio part of zap_huge_pmd()

[Baolin Wang]

On 3/21/26 2:07 AM, Lorenzo Stoakes (Oracle) wrote:
> Place the part of the logic that manipulates counters and possibly updates
> the accessed bit of the folio into its own function to make zap_huge_pmd()
> more readable.
>
> Also rename flush_needed to is_present as we only require a flush for
> present entries.
>
> Additionally add comments as to why we're doing what we're doing with
> respect to softleaf entries.
>
> This also lays the ground for further refactoring.
>
> Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@xxxxxxxxxx>
> ---
>   mm/huge_memory.c | 61 +++++++++++++++++++++++++++---------------------
>   1 file changed, 35 insertions(+), 26 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 673d0c4734ad..9ddf38d68406 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2325,6 +2325,37 @@ static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
>   	mm_dec_nr_ptes(mm);
>   }
>   
> +static void zap_huge_pmd_folio(struct mm_struct *mm, struct vm_area_struct *vma,
> +		pmd_t pmdval, struct folio *folio, bool is_present,
> +		bool *has_deposit)
> +{
> +	const bool is_device_private = folio_is_device_private(folio);
> +
> +	/* Present and device private folios are rmappable. */
> +	if (is_present || is_device_private)
> +		folio_remove_rmap_pmd(folio, &folio->page, vma);
> +
> +	if (folio_test_anon(folio)) {
> +		*has_deposit = true;
> +		add_mm_counter(mm, MM_ANONPAGES, -HPAGE_PMD_NR);
> +	} else {
> +		add_mm_counter(mm, mm_counter_file(folio),
> +			       -HPAGE_PMD_NR);
> +
> +		/*
> +		 * Use flush_needed to indicate whether the PMD entry
> +		 * is present, instead of checking pmd_present() again.
> +		 */
> +		if (is_present && pmd_young(pmdval) &&
> +		    likely(vma_has_recency(vma)))
> +			folio_mark_accessed(folio);

Nit: these comments were added by me to explain why 'flush_needed' was 
used:). Since it has been renamed to the more readable 'is_present', 
these comments are now redundant and can be removed.

With that,
Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>