include/linux/migrate.h: remove unneeded externs

As suggested by Matthew.

Suggested-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/migrate.h

@@ -62,16 +62,16 @@ extern const char *migrate_reason_names[MR_TYPES];
 
 #ifdef CONFIG_MIGRATION
 
-extern void putback_movable_pages(struct list_head *l);
+void putback_movable_pages(struct list_head *l);
 int migrate_folio_extra(struct address_space *mapping, struct folio *dst,
 		struct folio *src, enum migrate_mode mode, int extra_count);
 int migrate_folio(struct address_space *mapping, struct folio *dst,
 		struct folio *src, enum migrate_mode mode);
-extern int migrate_pages(struct list_head *l, new_page_t new, free_page_t free,
-		unsigned long private, enum migrate_mode mode, int reason,
-		unsigned int *ret_succeeded);
-extern struct page *alloc_migration_target(struct page *page, unsigned long private);
-extern bool isolate_movable_page(struct page *page, isolate_mode_t mode);
+int migrate_pages(struct list_head *l, new_page_t new, free_page_t free,
+		  unsigned long private, enum migrate_mode mode, int reason,
+		  unsigned int *ret_succeeded);
+struct page *alloc_migration_target(struct page *page, unsigned long private);
+bool isolate_movable_page(struct page *page, isolate_mode_t mode);
 
 int migrate_huge_page_move_mapping(struct address_space *mapping,
 		struct folio *dst, struct folio *src);
@@ -142,8 +142,8 @@ const struct movable_operations *page_movable_ops(struct page *page)
 }
 
 #ifdef CONFIG_NUMA_BALANCING
-extern int migrate_misplaced_page(struct page *page,
-				  struct vm_area_struct *vma, int node);
+int migrate_misplaced_page(struct page *page, struct vm_area_struct *vma,
+			   int node);
 #else
 static inline int migrate_misplaced_page(struct page *page,
 					 struct vm_area_struct *vma, int node)