mm: generate PAGE_IDLE_FLAG definitions

If CONFIG_PAGE_IDLE_FLAG is not set, we can use FOLIO_FLAG_FALSE() to
generate these definitions.

Link: https://lkml.kernel.org/r/20240402201252.917342-5-willy@infradead.orgSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

include/linux/page-flags.h

@@ -626,12 +626,19 @@ PAGEFLAG_FALSE(HWPoison, hwpoison)
 #define __PG_HWPOISON 0
 #endif
 
-#if defined(CONFIG_PAGE_IDLE_FLAG) && defined(CONFIG_64BIT)
+#ifdef CONFIG_PAGE_IDLE_FLAG
+#ifdef CONFIG_64BIT
 FOLIO_TEST_FLAG(young, FOLIO_HEAD_PAGE)
 FOLIO_SET_FLAG(young, FOLIO_HEAD_PAGE)
 FOLIO_TEST_CLEAR_FLAG(young, FOLIO_HEAD_PAGE)
 FOLIO_FLAG(idle, FOLIO_HEAD_PAGE)
 #endif
+/* See page_idle.h for !64BIT workaround */
+#else /* !CONFIG_PAGE_IDLE_FLAG */
+FOLIO_FLAG_FALSE(young)
+FOLIO_TEST_CLEAR_FLAG_FALSE(young)
+FOLIO_FLAG_FALSE(idle)
+#endif
 
 /*
  * PageReported() is used to track reported free pages within the Buddy

include/linux/page_idle.h

@@ -6,9 +6,7 @@
 #include <linux/page-flags.h>
 #include <linux/page_ext.h>
 
-#ifdef CONFIG_PAGE_IDLE_FLAG
-
-#ifndef CONFIG_64BIT
+#if defined(CONFIG_PAGE_IDLE_FLAG) && !defined(CONFIG_64BIT)
 /*
  * If there is not enough space to store Idle and Young bits in page flags, use
  * page ext flags instead.
@@ -87,36 +85,5 @@ static inline void folio_clear_idle(struct folio *folio)
 	clear_bit(PAGE_EXT_IDLE, &page_ext->flags);
 	page_ext_put(page_ext);
 }
-#endif /* !CONFIG_64BIT */
-
-#else /* !CONFIG_PAGE_IDLE_FLAG */
-
-static inline bool folio_test_young(const struct folio *folio)
-{
-	return false;
-}
-
-static inline void folio_set_young(struct folio *folio)
-{
-}
-
-static inline bool folio_test_clear_young(struct folio *folio)
-{
-	return false;
-}
-
-static inline bool folio_test_idle(const struct folio *folio)
-{
-	return false;
-}
-
-static inline void folio_set_idle(struct folio *folio)
-{
-}
-
-static inline void folio_clear_idle(struct folio *folio)
-{
-}
-
-#endif /* CONFIG_PAGE_IDLE_FLAG */
+#endif /* CONFIG_PAGE_IDLE_FLAG && !64BIT */
 #endif /* _LINUX_MM_PAGE_IDLE_H */