madvise: convert madvise_free_pte_range() to use a folio

Saves a lot of calls to compound_head().

Link: https://lkml.kernel.org/r/20220902194653.1739778-44-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/madvise.c

@@ -601,6 +601,7 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
 	struct vm_area_struct *vma = walk->vma;
 	spinlock_t *ptl;
 	pte_t *orig_pte, *pte, ptent;
+	struct folio *folio;
 	struct page *page;
 	int nr_swap = 0;
 	unsigned long next;
@@ -645,56 +646,56 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
 		page = vm_normal_page(vma, addr, ptent);
 		if (!page || is_zone_device_page(page))
 			continue;
+		folio = page_folio(page);
 
 		/*
-		 * If pmd isn't transhuge but the page is THP and
+		 * If pmd isn't transhuge but the folio is large and
 		 * is owned by only this process, split it and
 		 * deactivate all pages.
 		 */
-		if (PageTransCompound(page)) {
-			if (page_mapcount(page) != 1)
+		if (folio_test_large(folio)) {
+			if (folio_mapcount(folio) != 1)
 				goto out;
-			get_page(page);
-			if (!trylock_page(page)) {
-				put_page(page);
+			folio_get(folio);
+			if (!folio_trylock(folio)) {
+				folio_put(folio);
 				goto out;
 			}
 			pte_unmap_unlock(orig_pte, ptl);
-			if (split_huge_page(page)) {
-				unlock_page(page);
-				put_page(page);
+			if (split_folio(folio)) {
+				folio_unlock(folio);
+				folio_put(folio);
 				orig_pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
 				goto out;
 			}
-			unlock_page(page);
-			put_page(page);
+			folio_unlock(folio);
+			folio_put(folio);
 			orig_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
 			pte--;
 			addr -= PAGE_SIZE;
 			continue;
 		}
 
-		VM_BUG_ON_PAGE(PageTransCompound(page), page);
-
-		if (PageSwapCache(page) || PageDirty(page)) {
-			if (!trylock_page(page))
+		if (folio_test_swapcache(folio) || folio_test_dirty(folio)) {
+			if (!folio_trylock(folio))
 				continue;
 			/*
-			 * If page is shared with others, we couldn't clear
-			 * PG_dirty of the page.
+			 * If folio is shared with others, we mustn't clear
+			 * the folio's dirty flag.
 			 */
-			if (page_mapcount(page) != 1) {
-				unlock_page(page);
+			if (folio_mapcount(folio) != 1) {
+				folio_unlock(folio);
 				continue;
 			}
 
-			if (PageSwapCache(page) && !try_to_free_swap(page)) {
-				unlock_page(page);
+			if (folio_test_swapcache(folio) &&
+			    !folio_free_swap(folio)) {
+				folio_unlock(folio);
 				continue;
 			}
 
-			ClearPageDirty(page);
-			unlock_page(page);
+			folio_clear_dirty(folio);
+			folio_unlock(folio);
 		}
 
 		if (pte_young(ptent) || pte_dirty(ptent)) {
@@ -712,7 +713,7 @@ static int madvise_free_pte_range(pmd_t *pmd, unsigned long addr,
 			set_pte_at(mm, addr, pte, ptent);
 			tlb_remove_tlb_entry(tlb, pte, addr);
 		}
-		mark_page_lazyfree(page);
+		mark_page_lazyfree(&folio->page);
 	}
 out:
 	if (nr_swap) {