mm: migrate_device: use more folio in migrate_device_unmap()

The page for migrate_device_unmap() already has a reference, so it is safe
to convert the page to folio to save a few calls to compound_head(), which
removes the last isolate_lru_page() call.

Link: https://lkml.kernel.org/r/20240826065814.1336616-4-wangkefeng.wang@huawei.comSigned-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/migrate_device.c

@@ -379,33 +379,33 @@ static unsigned long migrate_device_unmap(unsigned long *src_pfns,
 			continue;
 		}
 
-		/* ZONE_DEVICE pages are not on LRU */
-		if (!is_zone_device_page(page)) {
-			if (!PageLRU(page) && allow_drain) {
+		folio =	page_folio(page);
+		/* ZONE_DEVICE folios are not on LRU */
+		if (!folio_is_zone_device(folio)) {
+			if (!folio_test_lru(folio) && allow_drain) {
 				/* Drain CPU's lru cache */
 				lru_add_drain_all();
 				allow_drain = false;
 			}
 
-			if (!isolate_lru_page(page)) {
+			if (!folio_isolate_lru(folio)) {
 				src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
 				restore++;
 				continue;
 			}
 
 			/* Drop the reference we took in collect */
-			put_page(page);
+			folio_put(folio);
 		}
 
-		folio = page_folio(page);
 		if (folio_mapped(folio))
 			try_to_migrate(folio, 0);
 
-		if (page_mapped(page) ||
+		if (folio_mapped(folio) ||
 		    !migrate_vma_check_page(page, fault_page)) {
-			if (!is_zone_device_page(page)) {
-				get_page(page);
-				putback_lru_page(page);
+			if (!folio_is_zone_device(folio)) {
+				folio_get(folio);
+				folio_putback_lru(folio);
 			}
 
 			src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;