[PATCH 2/3] mm: mprotect: avoid unnecessary struct page accessing if pte_protnone()

[Kefeng Wang <wangkefeng.wang@huawei.com>]

If the pte_protnone() is true, we could avoid unnecessary struct page
accessing and reduce cache footprint when scanning page tables for prot
numa, the performance test of pmbench memory accessing benchmark
should be benifit, see more commit a818f5363a0e ("autonuma: reduce cache
footprint when scanning page tables").

Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 mm/mprotect.c | 21 +++++++++++----------
 1 file changed, 11 insertions(+), 10 deletions(-)

diff --git a/mm/mprotect.c b/mm/mprotect.c
index 51a28781de9d..0f31c09c1726 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -118,18 +118,13 @@ static int mprotect_folio_pte_batch(struct folio *folio, pte_t *ptep,
 	return folio_pte_batch_flags(folio, NULL, ptep, &pte, max_nr_ptes, flags);
 }
 
-static bool prot_numa_skip(struct vm_area_struct *vma, unsigned long addr,
-			   pte_t oldpte, pte_t *pte, int target_node,
-			   struct folio *folio)
+static bool prot_numa_skip(struct vm_area_struct *vma, int target_node,
+		struct folio *folio)
 {
 	bool ret = true;
 	bool toptier;
 	int nid;
 
-	/* Avoid TLB flush if possible */
-	if (pte_protnone(oldpte))
-		goto skip;
-
 	if (!folio)
 		goto skip;
 
@@ -307,17 +302,23 @@ static long change_pte_range(struct mmu_gather *tlb,
 			struct page *page;
 			pte_t ptent;
 
+			/*
+			 * Avoid TLB flush if possible and unnecessary struct
+			 * page accessing when prot numa.
+			 */
+			if (prot_numa && pte_protnone(oldpte))
+				continue;
+
 			page = vm_normal_page(vma, addr, oldpte);
 			if (page)
 				folio = page_folio(page);
+
 			/*
 			 * Avoid trapping faults against the zero or KSM
 			 * pages. See similar comment in change_huge_pmd.
 			 */
 			if (prot_numa) {
-				int ret = prot_numa_skip(vma, addr, oldpte, pte,
-							 target_node, folio);
-				if (ret) {
+				if (prot_numa_skip(vma, target_node, folio)) {
 
 					/* determine batch to skip */
 					nr_ptes = mprotect_folio_pte_batch(folio,
-- 
2.43.0