slub: record page flag overlays explicitly

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>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 7d8db1233e44..3fc586b7b90b 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -104,6 +104,10 @@ enum pageflags {
         /* XEN */
         PG_pinned = PG_owner_priv_1,
         PG_savepinned = PG_dirty,
+
+        /* SLUB */
+        PG_slub_frozen = PG_active,
+        PG_slub_debug = PG_error,
 };
 
 #ifndef __GENERATING_BOUNDS_H
@@ -169,6 +173,9 @@ PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved)
 PAGEFLAG(Private, private) __CLEARPAGEFLAG(Private, private)
         __SETPAGEFLAG(Private, private)
 
+__PAGEFLAG(SlubFrozen, slub_frozen)
+__PAGEFLAG(SlubDebug, slub_debug)
+
 /*
  * Only test-and-set exist for PG_writeback.  The unconditional operators are
  * risky: they bypass page accounting.