Use __GFP_PREZEROED and folio_test_clear_prezeroed() to skip folio_zero_user() in the PMD THP anonymous page allocation path when the page is already zeroed.
Signed-off-by: Michael S. Tsirkin <[email protected]> Assisted-by: Claude:claude-opus-4-6 --- mm/huge_memory.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 8e2746ea74ad..3b9b53fad0f1 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1256,7 +1256,7 @@ EXPORT_SYMBOL_GPL(thp_get_unmapped_area); static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma, unsigned long addr) { - gfp_t gfp = vma_thp_gfp_mask(vma); + gfp_t gfp = vma_thp_gfp_mask(vma) | __GFP_PREZEROED; const int order = HPAGE_PMD_ORDER; struct folio *folio; @@ -1285,7 +1285,7 @@ static struct folio *vma_alloc_anon_folio_pmd(struct vm_area_struct *vma, * make sure that the page corresponding to the faulting address will be * hot in the cache after zeroing. */ - if (user_alloc_needs_zeroing()) + if (user_alloc_needs_zeroing() && !folio_test_clear_prezeroed(folio)) folio_zero_user(folio, addr); /* * The memory barrier inside __folio_mark_uptodate makes sure that -- MST
