khugepaged: use a folio throughout hpage_collapse_scan_file()

Replace the use of pages with folios.  Saves a few calls to
compound_head() and removes some uses of obsolete functions.

Link: https://lkml.kernel.org/r/20240403171838.1445826-8-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/trace/events/huge_memory.h

@@ -174,10 +174,10 @@ TRACE_EVENT(mm_collapse_huge_page_swapin,
 
 TRACE_EVENT(mm_khugepaged_scan_file,
 
-	TP_PROTO(struct mm_struct *mm, struct page *page, struct file *file,
+	TP_PROTO(struct mm_struct *mm, struct folio *folio, struct file *file,
 		 int present, int swap, int result),
 
-	TP_ARGS(mm, page, file, present, swap, result),
+	TP_ARGS(mm, folio, file, present, swap, result),
 
 	TP_STRUCT__entry(
 		__field(struct mm_struct *, mm)
@@ -190,7 +190,7 @@ TRACE_EVENT(mm_khugepaged_scan_file,
 
 	TP_fast_assign(
 		__entry->mm = mm;
-		__entry->pfn = page ? page_to_pfn(page) : -1;
+		__entry->pfn = folio ? folio_pfn(folio) : -1;
 		__assign_str(filename, file->f_path.dentry->d_iname);
 		__entry->present = present;
 		__entry->swap = swap;

mm/khugepaged.c

@@ -2203,7 +2203,7 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr,
 				    struct file *file, pgoff_t start,
 				    struct collapse_control *cc)
 {
-	struct page *page = NULL;
+	struct folio *folio = NULL;
 	struct address_space *mapping = file->f_mapping;
 	XA_STATE(xas, &mapping->i_pages, start);
 	int present, swap;
@@ -2215,11 +2215,11 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr,
 	memset(cc->node_load, 0, sizeof(cc->node_load));
 	nodes_clear(cc->alloc_nmask);
 	rcu_read_lock();
-	xas_for_each(&xas, page, start + HPAGE_PMD_NR - 1) {
-		if (xas_retry(&xas, page))
+	xas_for_each(&xas, folio, start + HPAGE_PMD_NR - 1) {
+		if (xas_retry(&xas, folio))
 			continue;
 
-		if (xa_is_value(page)) {
+		if (xa_is_value(folio)) {
 			++swap;
 			if (cc->is_khugepaged &&
 			    swap > khugepaged_max_ptes_swap) {
@@ -2234,11 +2234,9 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr,
 		 * TODO: khugepaged should compact smaller compound pages
 		 * into a PMD sized page
 		 */
-		if (PageTransCompound(page)) {
-			struct page *head = compound_head(page);
-
-			result = compound_order(head) == HPAGE_PMD_ORDER &&
-					head->index == start
+		if (folio_test_large(folio)) {
+			result = folio_order(folio) == HPAGE_PMD_ORDER &&
+					folio->index == start
 					/* Maybe PMD-mapped */
 					? SCAN_PTE_MAPPED_HUGEPAGE
 					: SCAN_PAGE_COMPOUND;
@@ -2251,28 +2249,29 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr,
 			break;
 		}
 
-		node = page_to_nid(page);
+		node = folio_nid(folio);
 		if (hpage_collapse_scan_abort(node, cc)) {
 			result = SCAN_SCAN_ABORT;
 			break;
 		}
 		cc->node_load[node]++;
 
-		if (!PageLRU(page)) {
+		if (!folio_test_lru(folio)) {
 			result = SCAN_PAGE_LRU;
 			break;
 		}
 
-		if (page_count(page) !=
-		    1 + page_mapcount(page) + page_has_private(page)) {
+		if (folio_ref_count(folio) !=
+		    1 + folio_mapcount(folio) + folio_test_private(folio)) {
 			result = SCAN_PAGE_COUNT;
 			break;
 		}
 
 		/*
-		 * We probably should check if the page is referenced here, but
-		 * nobody would transfer pte_young() to PageReferenced() for us.
-		 * And rmap walk here is just too costly...
+		 * We probably should check if the folio is referenced
+		 * here, but nobody would transfer pte_young() to
+		 * folio_test_referenced() for us.  And rmap walk here
+		 * is just too costly...
 		 */
 
 		present++;
@@ -2294,7 +2293,7 @@ static int hpage_collapse_scan_file(struct mm_struct *mm, unsigned long addr,
 		}
 	}
 
-	trace_mm_khugepaged_scan_file(mm, page, file, present, swap, result);
+	trace_mm_khugepaged_scan_file(mm, folio, file, present, swap, result);
 	return result;
 }
 #else