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

Baolin Wang
2026-03-21T05:59:47Z

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@kernel.org>
> ---
> 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@linux.alibaba.com>