[PATCH 2/3] slub: record page flag overlays explicitly

[Andy Whitcroft <apw@shadowen.org>]

SLUB reuses two page bits for internal purposes, it overlays PG_active
and PG_error.  This is hidden away in slub.c.  Document these overlays
explicitly in the main page-flags enum along with all the others.

Signed-off-by: Andy Whitcroft <apw@shadowen.org>
---
 include/linux/page-flags.h |    4 ++++
 mm/slub.c                  |    4 ++--
 2 files changed, 6 insertions(+), 2 deletions(-)
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 2cc1fb1..2e88df6 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -103,6 +103,10 @@ enum pageflags {
 
 	/* XEN */
 	PG_pinned = PG_owner_priv_1,
+
+	/* SLUB */
+	PG_slub_frozen = PG_active,
+	PG_slub_debug = PG_error,
 };
 
 #ifndef __GENERATING_BOUNDS_H
diff --git a/mm/slub.c b/mm/slub.c
index a505a82..fd7c61a 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -102,10 +102,10 @@
  * 			the fast path and disables lockless freelists.
  */
 
-#define FROZEN (1 << PG_active)
+#define FROZEN (1 << PG_slub_frozen)
 
 #ifdef CONFIG_SLUB_DEBUG
-#define SLABDEBUG (1 << PG_error)
+#define SLABDEBUG (1 << PG_slub_debug)
 #else
 #define SLABDEBUG 0
 #endif