Re: [PATCH v3 07/13] mm/huge_memory: deduplicate zap deposited table call

[Suren Baghdasaryan <surenb@google.com>]

On Fri, Mar 20, 2026 at 11:07 AM Lorenzo Stoakes (Oracle)
<ljs@kernel.org> wrote:
>
> Rather than having separate logic for each case determining whether to zap
> the deposited table, simply track this via a boolean.
>
> We default this to whether the architecture requires it, and update it as
> required elsewhere.
>
> Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>

Reviewed-by: Suren Baghdasaryan <surenb@google.com>

> ---
>  mm/huge_memory.c | 22 ++++++++++------------
>  1 file changed, 10 insertions(+), 12 deletions(-)
>
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 4add863cd18f..fca44aec6022 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2337,6 +2337,7 @@ static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
>  bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
>                  pmd_t *pmd, unsigned long addr)
>  {
> +       bool has_deposit = arch_needs_pgtable_deposit();
>         struct folio *folio = NULL;
>         bool flush_needed = false;
>         spinlock_t *ptl;
> @@ -2357,23 +2358,19 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
>                                                 tlb->fullmm);
>         arch_check_zapped_pmd(vma, orig_pmd);
>         tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
> -       if (vma_is_special_huge(vma)) {
> -               if (arch_needs_pgtable_deposit())
> -                       zap_deposited_table(tlb->mm, pmd);
> +       if (vma_is_special_huge(vma))
>                 goto out;
> -       }
>         if (is_huge_zero_pmd(orig_pmd)) {
> -               if (!vma_is_dax(vma) || arch_needs_pgtable_deposit())
> -                       zap_deposited_table(tlb->mm, pmd);
> +               if (!vma_is_dax(vma))
> +                       has_deposit = true;
>                 goto out;
>         }
>
>         if (pmd_present(orig_pmd)) {
> -               struct page *page = pmd_page(orig_pmd);
> +               folio = pmd_folio(orig_pmd);
>
>                 flush_needed = true;
> -               folio = page_folio(page);
> -               folio_remove_rmap_pmd(folio, page, vma);
> +               folio_remove_rmap_pmd(folio, &folio->page, vma);
>                 WARN_ON_ONCE(folio_mapcount(folio) < 0);
>         } else if (pmd_is_valid_softleaf(orig_pmd)) {
>                 const softleaf_t entry = softleaf_from_pmd(orig_pmd);
> @@ -2388,11 +2385,9 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
>         }
>
>         if (folio_test_anon(folio)) {
> -               zap_deposited_table(tlb->mm, pmd);
> +               has_deposit = true;
>                 add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
>         } else {
> -               if (arch_needs_pgtable_deposit())
> -                       zap_deposited_table(tlb->mm, pmd);
>                 add_mm_counter(tlb->mm, mm_counter_file(folio),
>                                -HPAGE_PMD_NR);
>
> @@ -2412,6 +2407,9 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
>         }
>
>  out:
> +       if (has_deposit)
> +               zap_deposited_table(tlb->mm, pmd);
> +
>         spin_unlock(ptl);
>         if (flush_needed)
>                 tlb_remove_page_size(tlb, &folio->page, HPAGE_PMD_SIZE);
> --
> 2.53.0
>