mm/memcg: Convert mem_cgroup_move_account() to use a folio

This saves dozens of bytes of text by eliminating a lot of calls to
compound_head().
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: David Howells <dhowells@redhat.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>

mm/memcontrol.c

@@ -5567,38 +5567,39 @@ static int mem_cgroup_move_account(struct page *page,
 				   struct mem_cgroup *from,
 				   struct mem_cgroup *to)
 {
+	struct folio *folio = page_folio(page);
 	struct lruvec *from_vec, *to_vec;
 	struct pglist_data *pgdat;
-	unsigned int nr_pages = compound ? thp_nr_pages(page) : 1;
+	unsigned int nr_pages = compound ? folio_nr_pages(folio) : 1;
 	int nid, ret;
 
 	VM_BUG_ON(from == to);
-	VM_BUG_ON_PAGE(PageLRU(page), page);
-	VM_BUG_ON(compound && !PageTransHuge(page));
+	VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
+	VM_BUG_ON(compound && !folio_test_multi(folio));
 
 	/*
 	 * Prevent mem_cgroup_migrate() from looking at
 	 * page's memory cgroup of its source page while we change it.
 	 */
 	ret = -EBUSY;
-	if (!trylock_page(page))
+	if (!folio_trylock(folio))
 		goto out;
 
 	ret = -EINVAL;
-	if (page_memcg(page) != from)
+	if (folio_memcg(folio) != from)
 		goto out_unlock;
 
-	pgdat = page_pgdat(page);
+	pgdat = folio_pgdat(folio);
 	from_vec = mem_cgroup_lruvec(from, pgdat);
 	to_vec = mem_cgroup_lruvec(to, pgdat);
 
-	lock_page_memcg(page);
+	folio_memcg_lock(folio);
 
-	if (PageAnon(page)) {
-		if (page_mapped(page)) {
+	if (folio_test_anon(folio)) {
+		if (folio_mapped(folio)) {
 			__mod_lruvec_state(from_vec, NR_ANON_MAPPED, -nr_pages);
 			__mod_lruvec_state(to_vec, NR_ANON_MAPPED, nr_pages);
-			if (PageTransHuge(page)) {
+			if (folio_test_transhuge(folio)) {
 				__mod_lruvec_state(from_vec, NR_ANON_THPS,
 						   -nr_pages);
 				__mod_lruvec_state(to_vec, NR_ANON_THPS,
@@ -5609,18 +5610,18 @@ static int mem_cgroup_move_account(struct page *page,
 		__mod_lruvec_state(from_vec, NR_FILE_PAGES, -nr_pages);
 		__mod_lruvec_state(to_vec, NR_FILE_PAGES, nr_pages);
 
-		if (PageSwapBacked(page)) {
+		if (folio_test_swapbacked(folio)) {
 			__mod_lruvec_state(from_vec, NR_SHMEM, -nr_pages);
 			__mod_lruvec_state(to_vec, NR_SHMEM, nr_pages);
 		}
 
-		if (page_mapped(page)) {
+		if (folio_mapped(folio)) {
 			__mod_lruvec_state(from_vec, NR_FILE_MAPPED, -nr_pages);
 			__mod_lruvec_state(to_vec, NR_FILE_MAPPED, nr_pages);
 		}
 
-		if (PageDirty(page)) {
-			struct address_space *mapping = page_mapping(page);
+		if (folio_test_dirty(folio)) {
+			struct address_space *mapping = folio_mapping(folio);
 
 			if (mapping_can_writeback(mapping)) {
 				__mod_lruvec_state(from_vec, NR_FILE_DIRTY,
@@ -5631,7 +5632,7 @@ static int mem_cgroup_move_account(struct page *page,
 		}
 	}
 
-	if (PageWriteback(page)) {
+	if (folio_test_writeback(folio)) {
 		__mod_lruvec_state(from_vec, NR_WRITEBACK, -nr_pages);
 		__mod_lruvec_state(to_vec, NR_WRITEBACK, nr_pages);
 	}
@@ -5654,12 +5655,12 @@ static int mem_cgroup_move_account(struct page *page,
 	css_get(&to->css);
 	css_put(&from->css);
 
-	page->memcg_data = (unsigned long)to;
+	folio->memcg_data = (unsigned long)to;
 
 	__folio_memcg_unlock(from);
 
 	ret = 0;
-	nid = page_to_nid(page);
+	nid = folio_nid(folio);
 
 	local_irq_disable();
 	mem_cgroup_charge_statistics(to, nr_pages);
@@ -5668,7 +5669,7 @@ static int mem_cgroup_move_account(struct page *page,
 	memcg_check_events(from, nid);
 	local_irq_enable();
 out_unlock:
-	unlock_page(page);
+	folio_unlock(folio);
 out:
 	return ret;
 }