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

Lorenzo Stoakes (Oracle)
2026-03-20T18:07:56Z

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>
---
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