Re: [PATCH v3 03/13] mm/huge_memory: have zap_huge_pmd return a boolean, add kdoc

[Suren Baghdasaryan <surenb@google.com>]

On Fri, Mar 20, 2026 at 11:07 AM Lorenzo Stoakes (Oracle)
<ljs@kernel.org> wrote:
>
> There's no need to use the ancient approach of returning an integer here,
> just return a boolean.
>
> Also update flush_needed to be a boolean, similarly.
>
> Also add a kdoc comment describing the function.
>
> No functional change intended.
>
> Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
> Acked-by: Qi Zheng <zhengqi.arch@bytedance.com>
> Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>

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

> ---
>  include/linux/huge_mm.h |  4 ++--
>  mm/huge_memory.c        | 23 ++++++++++++++++-------
>  2 files changed, 18 insertions(+), 9 deletions(-)
>
> diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
> index af726f0aa30d..1258fa37e85b 100644
> --- a/include/linux/huge_mm.h
> +++ b/include/linux/huge_mm.h
> @@ -27,8 +27,8 @@ static inline void huge_pud_set_accessed(struct vm_fault *vmf, pud_t orig_pud)
>  vm_fault_t do_huge_pmd_wp_page(struct vm_fault *vmf);
>  bool madvise_free_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
>                            pmd_t *pmd, unsigned long addr, unsigned long next);
> -int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, pmd_t *pmd,
> -                unsigned long addr);
> +bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, pmd_t *pmd,
> +                 unsigned long addr);
>  int zap_huge_pud(struct mmu_gather *tlb, struct vm_area_struct *vma, pud_t *pud,
>                  unsigned long addr);
>  bool move_huge_pmd(struct vm_area_struct *vma, unsigned long old_addr,
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 4e8df3a35cab..3c9e2ebaacfa 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2325,11 +2325,20 @@ static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)
>         mm_dec_nr_ptes(mm);
>  }
>
> -int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
> +/**
> + * zap_huge_pmd - Zap a huge THP which is of PMD size.
> + * @tlb: The MMU gather TLB state associated with the operation.
> + * @vma: The VMA containing the range to zap.
> + * @pmd: A pointer to the leaf PMD entry.
> + * @addr: The virtual address for the range to zap.
> + *
> + * Returns: %true on success, %false otherwise.
> + */
> +bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
>                  pmd_t *pmd, unsigned long addr)
>  {
>         struct folio *folio = NULL;
> -       int flush_needed = 1;
> +       bool flush_needed = true;
>         spinlock_t *ptl;
>         pmd_t orig_pmd;
>
> @@ -2337,7 +2346,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
>
>         ptl = __pmd_trans_huge_lock(pmd, vma);
>         if (!ptl)
> -               return 0;
> +               return false;
>         /*
>          * For architectures like ppc64 we look at deposited pgtable
>          * when calling pmdp_huge_get_and_clear. So do the
> @@ -2352,13 +2361,13 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
>                 if (arch_needs_pgtable_deposit())
>                         zap_deposited_table(tlb->mm, pmd);
>                 spin_unlock(ptl);
> -               return 1;
> +               return true;
>         }
>         if (is_huge_zero_pmd(orig_pmd)) {
>                 if (!vma_is_dax(vma) || arch_needs_pgtable_deposit())
>                         zap_deposited_table(tlb->mm, pmd);
>                 spin_unlock(ptl);
> -               return 1;
> +               return true;
>         }
>
>         if (pmd_present(orig_pmd)) {
> @@ -2372,7 +2381,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
>                 const softleaf_t entry = softleaf_from_pmd(orig_pmd);
>
>                 folio = softleaf_to_folio(entry);
> -               flush_needed = 0;
> +               flush_needed = false;
>
>                 if (!thp_migration_supported())
>                         WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");
> @@ -2406,7 +2415,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
>         if (flush_needed)
>                 tlb_remove_page_size(tlb, &folio->page, HPAGE_PMD_SIZE);
>
> -       return 1;
> +       return true;
>  }
>
>  #ifndef pmd_move_must_withdraw
> --
> 2.53.0
>