[PATCH v2 05/12] mm: hugetlb_vmemmap: unify writable vmemmap page preparation

@@ -199,6 +199,20 @@ static void free_vmemmap_page_list(struct list_head *list)
 		free_vmemmap_page(page);
 }
 
+static struct page *vmemmap_dup_page_from_list(const struct page *src,
+					       struct list_head *vmemmap_pages)
+{
+	struct page *dst = list_first_entry(vmemmap_pages, struct page, lru);
+
+	list_del(&dst->lru);
+	copy_page(page_address(dst), page_address(src));
+
+	/* Ensure updates to @dst page are visible before set_pte_at(). */
+	smp_wmb();
+
+	return dst;
+}
+
 static void vmemmap_remap_pte(pte_t *pte, unsigned long addr,
 			      struct vmemmap_remap_walk *walk)
 {

@@ -211,16 +225,7 @@ static void vmemmap_remap_pte(pte_t *pte, unsigned long addr,
 
 		VM_WARN_ON_ONCE(!PageHead((const struct page *)addr));
 
-		head = list_first_entry(walk->vmemmap_pages, struct page, lru);
-		list_del(&head->lru);
-
-		/*
-		 * Makes sure that preceding stores to the page contents from
-		 * vmemmap_remap_free() become visible before the set_pte_at()
-		 * write.
-		 */
-		smp_wmb();
-
+		head = vmemmap_dup_page_from_list(page, walk->vmemmap_pages);
 		entry = mk_pte(head, PAGE_KERNEL);
 	} else {
 		VM_WARN_ON_ONCE(!PageTail((const struct page *)addr));

@@ -253,15 +258,7 @@ static void vmemmap_restore_pte(pte_t *pte, unsigned long addr,
 
 	VM_WARN_ON_ONCE(PageHead((const struct page *)addr));
 
-	dst = list_first_entry(walk->vmemmap_pages, struct page, lru);
-	list_del(&dst->lru);
-	copy_page(page_to_virt(dst), page_to_virt(src));
-
-	/*
-	 * Makes sure that preceding stores to the page contents become visible
-	 * before the set_pte_at() write.
-	 */
-	smp_wmb();
+	dst = vmemmap_dup_page_from_list(src, walk->vmemmap_pages);
 	set_pte_at(&init_mm, addr, pte, mk_pte(dst, PAGE_KERNEL));
 }
 

@@ -499,7 +496,7 @@ static int __hugetlb_vmemmap_optimize_folio(const struct hstate *h,
 					    unsigned long flags)
 {
 	unsigned long vmemmap_start, vmemmap_end;
-	struct page *vmemmap_head, *vmemmap_tail;
+	struct page *vmemmap_tail;
 	int nid, ret = 0;
 
 	VM_WARN_ON_ONCE_FOLIO(!folio_test_hugetlb(folio), folio);

@@ -531,9 +528,6 @@ static int __hugetlb_vmemmap_optimize_folio(const struct hstate *h,
 		goto out;
 	}
 
-	vmemmap_head = list_first_entry(vmemmap_pages, struct page, lru);
-	copy_page(page_to_virt(vmemmap_head), folio);
-
 	vmemmap_start	= (unsigned long)&folio->page;
 	vmemmap_end	= vmemmap_start + hugetlb_vmemmap_size(h);