[PATCH 1/3] madvise: Convert madvise_cold_or_pageout_pte_range() to use folios

[Vishal Moola (Oracle)]

This change removes a number of calls to compound_head(), and saves 1319
bytes of kernel text.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@xxxxxxxxx>
---
 mm/madvise.c | 88 +++++++++++++++++++++++++++-------------------------
 1 file changed, 45 insertions(+), 43 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index 2baa93ca2310..59bfc6c9c548 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -332,8 +332,9 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
 	struct vm_area_struct *vma = walk->vma;
 	pte_t *orig_pte, *pte, ptent;
 	spinlock_t *ptl;
+	struct folio *folio = NULL;
 	struct page *page = NULL;
-	LIST_HEAD(page_list);
+	LIST_HEAD(folio_list);
 
 	if (fatal_signal_pending(current))
 		return -EINTR;
@@ -358,23 +359,23 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
 			goto huge_unlock;
 		}
 
-		page = pmd_page(orig_pmd);
+		folio = pfn_folio(pmd_pfn(orig_pmd));
 
-		/* Do not interfere with other mappings of this page */
-		if (page_mapcount(page) != 1)
+		/* Do not interfere with other mappings of this folio */
+		if (folio_mapcount(folio) != 1)
 			goto huge_unlock;
 
 		if (next - addr != HPAGE_PMD_SIZE) {
 			int err;
 
-			get_page(page);
+			folio_get(folio);
 			spin_unlock(ptl);
-			lock_page(page);
-			err = split_huge_page(page);
-			unlock_page(page);
-			put_page(page);
+			folio_lock(folio);
+			err = split_folio(folio);
+			folio_unlock(folio);
+			folio_put(folio);
 			if (!err)
-				goto regular_page;
+				goto regular_folio;
 			return 0;
 		}
 
@@ -386,25 +387,25 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
 			tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
 		}
 
-		ClearPageReferenced(page);
-		test_and_clear_page_young(page);
+		folio_clear_referenced(folio);
+		folio_test_clear_young(folio);
 		if (pageout) {
-			if (!isolate_lru_page(page)) {
-				if (PageUnevictable(page))
-					putback_lru_page(page);
+			if (!folio_isolate_lru(folio)) {
+				if (folio_test_unevictable(folio))
+					folio_putback_lru(folio);
 				else
-					list_add(&page->lru, &page_list);
+					list_add(&folio->lru, &folio_list);
 			}
 		} else
-			deactivate_page(page);
+			deactivate_page(&folio->page);
 huge_unlock:
 		spin_unlock(ptl);
 		if (pageout)
-			reclaim_pages(&page_list);
+			reclaim_pages(&folio_list);
 		return 0;
 	}
 
-regular_page:
+regular_folio:
 	if (pmd_trans_unstable(pmd))
 		return 0;
 #endif
@@ -424,28 +425,29 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
 		page = vm_normal_page(vma, addr, ptent);
 		if (!page || is_zone_device_page(page))
 			continue;
+		folio = page_folio(page);
 
 		/*
 		 * Creating a THP page is expensive so split it only if we
 		 * are sure it's worth. Split it if we are only owner.
 		 */
-		if (PageTransCompound(page)) {
-			if (page_mapcount(page) != 1)
+		if (folio_test_large(folio)) {
+			if (folio_mapcount(folio) != 1)
 				break;
-			get_page(page);
-			if (!trylock_page(page)) {
-				put_page(page);
+			folio_get(folio);
+			if (!folio_trylock(folio)) {
+				folio_put(folio);
 				break;
 			}
 			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);
 				break;
 			}
-			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;
@@ -453,13 +455,13 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
 		}
 
 		/*
-		 * Do not interfere with other mappings of this page and
-		 * non-LRU page.
+		 * Do not interfere with other mappings of this folio and
+		 * non-LRU folio.
 		 */
-		if (!PageLRU(page) || page_mapcount(page) != 1)
+		if (!folio_test_lru(folio))
 			continue;
 
-		VM_BUG_ON_PAGE(PageTransCompound(page), page);
+		VM_BUG_ON_PAGE(folio_test_large(folio), folio);
 
 		if (pte_young(ptent)) {
 			ptent = ptep_get_and_clear_full(mm, addr, pte,
@@ -470,28 +472,28 @@ static int madvise_cold_or_pageout_pte_range(pmd_t *pmd,
 		}
 
 		/*
-		 * We are deactivating a page for accelerating reclaiming.
-		 * VM couldn't reclaim the page unless we clear PG_young.
+		 * We are deactivating a folio for accelerating reclaiming.
+		 * VM couldn't reclaim the folio unless we clear PG_young.
 		 * As a side effect, it makes confuse idle-page tracking
 		 * because they will miss recent referenced history.
 		 */
-		ClearPageReferenced(page);
-		test_and_clear_page_young(page);
+		folio_clear_referenced(folio);
+		folio_test_clear_young(folio);
 		if (pageout) {
-			if (!isolate_lru_page(page)) {
-				if (PageUnevictable(page))
-					putback_lru_page(page);
+			if (!folio_isolate_lru(folio)) {
+				if (folio_test_unevictable(folio))
+					folio_putback_lru(folio);
 				else
-					list_add(&page->lru, &page_list);
+					list_add(&folio->lru, &folio_list);
 			}
 		} else
-			deactivate_page(page);
+			deactivate_page(&folio->page);
 	}
 
 	arch_leave_lazy_mmu_mode();
 	pte_unmap_unlock(orig_pte, ptl);
 	if (pageout)
-		reclaim_pages(&page_list);
+		reclaim_pages(&folio_list);
 	cond_resched();
 
 	return 0;
-- 
2.38.1