treewide: remove MIGRATEPAGE_SUCCESS

At this point MIGRATEPAGE_SUCCESS is misnamed for all folio users,
and now that we remove MIGRATEPAGE_UNMAP, it's really the only "success"
return value that the code uses and expects.

Let's just get rid of MIGRATEPAGE_SUCCESS completely and just use "0"
for success.

Link: https://lkml.kernel.org/r/20250811143949.1117439-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>			[mm]
Acked-by: Dave Kleikamp <dave.kleikamp@oracle.com>	[jfs]
Acked-by: David Sterba <dsterba@suse.com>		[btrfs]
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Byungchul Park <byungchul@sk.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin LaHaise <bcrl@kvack.org>
Cc: Chris Mason <clm@fb.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Kleikamp <shaggy@kernel.org>
Cc: Eugenio Pé rez <eperezma@redhat.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jerrin Shaji George <jerrin.shaji-george@broadcom.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: Lance Yang <lance.yang@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

arch/powerpc/platforms/pseries/cmm.c

@@ -545,7 +545,7 @@ static int cmm_migratepage(struct balloon_dev_info *b_dev_info,
 	/* balloon page list reference */
 	put_page(page);
 
-	return MIGRATEPAGE_SUCCESS;
+	return 0;
 }
 
 static void cmm_balloon_compaction_init(void)

drivers/misc/vmw_balloon.c

@@ -1806,7 +1806,7 @@ static int vmballoon_migratepage(struct balloon_dev_info *b_dev_info,
 		 * the list after acquiring the lock.
 		 */
 		get_page(newpage);
-		ret = MIGRATEPAGE_SUCCESS;
+		ret = 0;
 	}
 
 	/* Update the balloon list under the @pages_lock */
@@ -1817,7 +1817,7 @@ static int vmballoon_migratepage(struct balloon_dev_info *b_dev_info,
 	 * If we succeed just insert it to the list and update the statistics
 	 * under the lock.
 	 */
-	if (ret == MIGRATEPAGE_SUCCESS) {
+	if (!ret) {
 		balloon_page_insert(&b->b_dev_info, newpage);
 		__count_vm_event(BALLOON_MIGRATE);
 	}

drivers/virtio/virtio_balloon.c

@@ -875,7 +875,7 @@ static int virtballoon_migratepage(struct balloon_dev_info *vb_dev_info,
 	balloon_page_finalize(page);
 	put_page(page); /* balloon reference */
 
-	return MIGRATEPAGE_SUCCESS;
+	return 0;
 }
 #endif /* CONFIG_BALLOON_COMPACTION */
 

fs/aio.c

@@ -445,7 +445,7 @@ static int aio_migrate_folio(struct address_space *mapping, struct folio *dst,
 	folio_get(dst);
 
 	rc = folio_migrate_mapping(mapping, dst, src, 1);
-	if (rc != MIGRATEPAGE_SUCCESS) {
+	if (rc) {
 		folio_put(dst);
 		goto out_unlock;
 	}

fs/btrfs/inode.c

@@ -7421,7 +7421,7 @@ static int btrfs_migrate_folio(struct address_space *mapping,
 {
 	int ret = filemap_migrate_folio(mapping, dst, src, mode);
 
-	if (ret != MIGRATEPAGE_SUCCESS)
+	if (ret)
 		return ret;
 
 	if (folio_test_ordered(src)) {
@@ -7429,7 +7429,7 @@ static int btrfs_migrate_folio(struct address_space *mapping,
 		folio_set_ordered(dst);
 	}
 
-	return MIGRATEPAGE_SUCCESS;
+	return 0;
 }
 #else
 #define btrfs_migrate_folio NULL

fs/hugetlbfs/inode.c

@@ -1052,7 +1052,7 @@ static int hugetlbfs_migrate_folio(struct address_space *mapping,
 	int rc;
 
 	rc = migrate_huge_page_move_mapping(mapping, dst, src);
-	if (rc != MIGRATEPAGE_SUCCESS)
+	if (rc)
 		return rc;
 
 	if (hugetlb_folio_subpool(src)) {
@@ -1063,7 +1063,7 @@ static int hugetlbfs_migrate_folio(struct address_space *mapping,
 
 	folio_migrate_flags(dst, src);
 
-	return MIGRATEPAGE_SUCCESS;
+	return 0;
 }
 #else
 #define hugetlbfs_migrate_folio NULL

fs/jfs/jfs_metapage.c

@@ -169,7 +169,7 @@ static int __metapage_migrate_folio(struct address_space *mapping,
 	}
 
 	rc = filemap_migrate_folio(mapping, dst, src, mode);
-	if (rc != MIGRATEPAGE_SUCCESS)
+	if (rc)
 		return rc;
 
 	for (i = 0; i < MPS_PER_PAGE; i++) {
@@ -199,7 +199,7 @@ static int __metapage_migrate_folio(struct address_space *mapping,
 		}
 	}
 
-	return MIGRATEPAGE_SUCCESS;
+	return 0;
 }
 #endif	/* CONFIG_MIGRATION */
 
@@ -242,7 +242,7 @@ static int __metapage_migrate_folio(struct address_space *mapping,
 		return -EAGAIN;
 
 	rc = filemap_migrate_folio(mapping, dst, src, mode);
-	if (rc != MIGRATEPAGE_SUCCESS)
+	if (rc)
 		return rc;
 
 	if (unlikely(insert_metapage(dst, mp)))
@@ -253,7 +253,7 @@ static int __metapage_migrate_folio(struct address_space *mapping,
 	mp->folio = dst;
 	remove_metapage(src, mp);
 
-	return MIGRATEPAGE_SUCCESS;
+	return 0;
 }
 #endif	/* CONFIG_MIGRATION */
 

include/linux/migrate.h

@@ -12,13 +12,6 @@ typedef void free_folio_t(struct folio *folio, unsigned long private);
 
 struct migration_target_control;
 
-/*
- * Return values from addresss_space_operations.migratepage():
- * - negative errno on page migration failure;
- * - zero on page migration success;
- */
-#define MIGRATEPAGE_SUCCESS		0
-
 /**
  * struct movable_operations - Driver page migration
  * @isolate_page:
@@ -34,8 +27,7 @@ struct migration_target_control;
  * @src page.  The driver should copy the contents of the
  * @src page to the @dst page and set up the fields of @dst page.
  * Both pages are locked.
- * If page migration is successful, the driver should
- * return MIGRATEPAGE_SUCCESS.
+ * If page migration is successful, the driver should return 0.
  * If the driver cannot migrate the page at the moment, it can return
  * -EAGAIN.  The VM interprets this as a temporary migration failure and
  * will retry it later.  Any other error value is a permanent migration

mm/migrate.c

@@ -231,18 +231,17 @@ static void putback_movable_ops_page(struct page *page)
  * src and dst are also released by migration core. These pages will not be
  * folios in the future, so that must be reworked.
  *
- * Returns MIGRATEPAGE_SUCCESS on success, otherwise a negative error
- * code.
+ * Returns 0 on success, otherwise a negative error code.
  */
 static int migrate_movable_ops_page(struct page *dst, struct page *src,
 		enum migrate_mode mode)
 {
-	int rc = MIGRATEPAGE_SUCCESS;
+	int rc;
 
 	VM_WARN_ON_ONCE_PAGE(!page_has_movable_ops(src), src);
 	VM_WARN_ON_ONCE_PAGE(!PageMovableOpsIsolated(src), src);
 	rc = page_movable_ops(src)->migrate_page(dst, src, mode);
-	if (rc == MIGRATEPAGE_SUCCESS)
+	if (!rc)
 		ClearPageMovableOpsIsolated(src);
 	return rc;
 }
@@ -587,7 +586,7 @@ static int __folio_migrate_mapping(struct address_space *mapping,
 		if (folio_test_swapbacked(folio))
 			__folio_set_swapbacked(newfolio);
 
-		return MIGRATEPAGE_SUCCESS;
+		return 0;
 	}
 
 	oldzone = folio_zone(folio);
@@ -688,7 +687,7 @@ static int __folio_migrate_mapping(struct address_space *mapping,
 	}
 	local_irq_enable();
 
-	return MIGRATEPAGE_SUCCESS;
+	return 0;
 }
 
 int folio_migrate_mapping(struct address_space *mapping,
@@ -737,7 +736,7 @@ int migrate_huge_page_move_mapping(struct address_space *mapping,
 
 	xas_unlock_irq(&xas);
 
-	return MIGRATEPAGE_SUCCESS;
+	return 0;
 }
 
 /*
@@ -853,14 +852,14 @@ static int __migrate_folio(struct address_space *mapping, struct folio *dst,
 		return rc;
 
 	rc = __folio_migrate_mapping(mapping, dst, src, expected_count);
-	if (rc != MIGRATEPAGE_SUCCESS)
+	if (rc)
 		return rc;
 
 	if (src_private)
 		folio_attach_private(dst, folio_detach_private(src));
 
 	folio_migrate_flags(dst, src);
-	return MIGRATEPAGE_SUCCESS;
+	return 0;
 }
 
 /**
@@ -967,7 +966,7 @@ recheck_buffers:
 	}
 
 	rc = filemap_migrate_folio(mapping, dst, src, mode);
-	if (rc != MIGRATEPAGE_SUCCESS)
+	if (rc)
 		goto unlock_buffers;
 
 	bh = head;
@@ -1071,7 +1070,7 @@ static int fallback_migrate_folio(struct address_space *mapping,
  *
  * Return value:
  *   < 0 - error code
- *  MIGRATEPAGE_SUCCESS - success
+ *     0 - success
  */
 static int move_to_new_folio(struct folio *dst, struct folio *src,
 				enum migrate_mode mode)
@@ -1099,7 +1098,7 @@ static int move_to_new_folio(struct folio *dst, struct folio *src,
 	else
 		rc = fallback_migrate_folio(mapping, dst, src, mode);
 
-	if (rc == MIGRATEPAGE_SUCCESS) {
+	if (!rc) {
 		/*
 		 * For pagecache folios, src->mapping must be cleared before src
 		 * is freed. Anonymous folios must stay anonymous until freed.
@@ -1449,7 +1448,7 @@ static int unmap_and_move_huge_page(new_folio_t get_new_folio,
 	if (folio_ref_count(src) == 1) {
 		/* page was freed from under us. So we are done. */
 		folio_putback_hugetlb(src);
-		return MIGRATEPAGE_SUCCESS;
+		return 0;
 	}
 
 	dst = get_new_folio(src, private);
@@ -1512,8 +1511,7 @@ static int unmap_and_move_huge_page(new_folio_t get_new_folio,
 		rc = move_to_new_folio(dst, src, mode);
 
 	if (page_was_mapped)
-		remove_migration_ptes(src,
-			rc == MIGRATEPAGE_SUCCESS ? dst : src, 0);
+		remove_migration_ptes(src, !rc ? dst : src, 0);
 
 unlock_put_anon:
 	folio_unlock(dst);
@@ -1522,7 +1520,7 @@ put_anon:
 	if (anon_vma)
 		put_anon_vma(anon_vma);
 
-	if (rc == MIGRATEPAGE_SUCCESS) {
+	if (!rc) {
 		move_hugetlb_state(src, dst, reason);
 		put_new_folio = NULL;
 	}
@@ -1530,7 +1528,7 @@ put_anon:
 out_unlock:
 	folio_unlock(src);
 out:
-	if (rc == MIGRATEPAGE_SUCCESS)
+	if (!rc)
 		folio_putback_hugetlb(src);
 	else if (rc != -EAGAIN)
 		list_move_tail(&src->lru, ret);
@@ -1640,7 +1638,7 @@ static int migrate_hugetlbs(struct list_head *from, new_folio_t get_new_folio,
 						      reason, ret_folios);
 			/*
 			 * The rules are:
-			 *	Success: hugetlb folio will be put back
+			 *	0: hugetlb folio will be put back
 			 *	-EAGAIN: stay on the from list
 			 *	-ENOMEM: stay on the from list
 			 *	Other errno: put on ret_folios list
@@ -1657,7 +1655,7 @@ static int migrate_hugetlbs(struct list_head *from, new_folio_t get_new_folio,
 				retry++;
 				nr_retry_pages += nr_pages;
 				break;
-			case MIGRATEPAGE_SUCCESS:
+			case 0:
 				stats->nr_succeeded += nr_pages;
 				break;
 			default:
@@ -1711,7 +1709,7 @@ static void migrate_folios_move(struct list_head *src_folios,
 				reason, ret_folios);
 		/*
 		 * The rules are:
-		 *	Success: folio will be freed
+		 *	0: folio will be freed
 		 *	-EAGAIN: stay on the unmap_folios list
 		 *	Other errno: put on ret_folios list
 		 */
@@ -1721,7 +1719,7 @@ static void migrate_folios_move(struct list_head *src_folios,
 			*thp_retry += is_thp;
 			*nr_retry_pages += nr_pages;
 			break;
-		case MIGRATEPAGE_SUCCESS:
+		case 0:
 			stats->nr_succeeded += nr_pages;
 			stats->nr_thp_succeeded += is_thp;
 			break;

mm/migrate_device.c

@@ -778,7 +778,7 @@ static void __migrate_device_pages(unsigned long *src_pfns,
 		if (migrate && migrate->fault_page == page)
 			extra_cnt = 1;
 		r = folio_migrate_mapping(mapping, newfolio, folio, extra_cnt);
-		if (r != MIGRATEPAGE_SUCCESS)
+		if (r)
 			src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
 		else
 			folio_migrate_flags(newfolio, folio);

mm/zsmalloc.c

@@ -1746,7 +1746,7 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
 	 * instead.
 	 */
 	if (!zpdesc->zspage)
-		return MIGRATEPAGE_SUCCESS;
+		return 0;
 
 	/* The page is locked, so this pointer must remain valid */
 	zspage = get_zspage(zpdesc);
@@ -1813,7 +1813,7 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
 	reset_zpdesc(zpdesc);
 	zpdesc_put(zpdesc);
 
-	return MIGRATEPAGE_SUCCESS;
+	return 0;
 }
 
 static void zs_page_putback(struct page *page)