[PATCH v5 08/28] mm: use __GFP_ZERO in alloc_anon_folio

[Michael S. Tsirkin]

Convert alloc_anon_folio() to pass __GFP_ZERO instead of zeroing
at the callsite. post_alloc_hook uses the fault address passed
through vma_alloc_folio for cache-friendly zeroing.

Also convert alloc_swap_folio() to pass the raw fault address
for the same cache-friendly zeroing benefit on swap-in.

Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Assisted-by: Claude:claude-opus-4-6
---
 mm/memory.c | 11 +----------
 1 file changed, 1 insertion(+), 10 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 70ab8b3e3a29..bb24a14d97c2 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -5175,7 +5175,7 @@ static struct folio *alloc_anon_folio(struct vm_fault *vmf)
 		goto fallback;
 
 	/* Try allocating the highest of the remaining orders. */
-	gfp = vma_thp_gfp_mask(vma);
+	gfp = vma_thp_gfp_mask(vma) | __GFP_ZERO;
 	while (orders) {
 		folio = vma_alloc_folio(gfp, order, vma, vmf->address);
 		if (folio) {
@@ -5185,15 +5185,6 @@ static struct folio *alloc_anon_folio(struct vm_fault *vmf)
 				goto next;
 			}
 			folio_throttle_swaprate(folio, gfp);
-			/*
-			 * When a folio is not zeroed during allocation
-			 * (__GFP_ZERO not used) or user folios require special
-			 * handling, folio_zero_user() is used to make sure
-			 * that the page corresponding to the faulting address
-			 * will be hot in the cache after zeroing.
-			 */
-			if (user_alloc_needs_zeroing())
-				folio_zero_user(folio, vmf->address);
 			return folio;
 		}
 next:
-- 
MST