mm: restore zone->all_unreclaimable to independence word

commit e815af95 ("change all_unreclaimable zone member to flags") changed
all_unreclaimable member to bit flag.  But it had an undesireble side
effect.  free_one_page() is one of most hot path in linux kernel and
increasing atomic ops in it can reduce kernel performance a bit.

Thus, this patch revert such commit partially. at least
all_unreclaimable shouldn't share memory word with other zone flags.

[akpm@linux-foundation.org: fix patch interaction]
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Cc: Huang Shijie <shijie8@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 6 deletions

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index a01a103341bd..bc209d8b7b5c 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -306,6 +306,7 @@ struct zone {
 	 * free areas of different sizes
 	 */
 	spinlock_t		lock;
+	int                     all_unreclaimable; /* All pages pinned */
 #ifdef CONFIG_MEMORY_HOTPLUG
 	/* see spanned/present_pages for more description */
 	seqlock_t		span_seqlock;
@@ -417,7 +418,6 @@ struct zone {
 } ____cacheline_internodealigned_in_smp;
 
 typedef enum {
-	ZONE_ALL_UNRECLAIMABLE,		/* all pages pinned */
 	ZONE_RECLAIM_LOCKED,		/* prevents concurrent reclaim */
 	ZONE_OOM_LOCKED,		/* zone is in OOM killer zonelist */
 } zone_flags_t;
@@ -437,11 +437,6 @@ static inline void zone_clear_flag(struct zone *zone, zone_flags_t flag)
 	clear_bit(flag, &zone->flags);
 }
 
-static inline int zone_is_all_unreclaimable(const struct zone *zone)
-{
-	return test_bit(ZONE_ALL_UNRECLAIMABLE, &zone->flags);
-}
-
 static inline int zone_is_reclaim_locked(const struct zone *zone)
 {
 	return test_bit(ZONE_RECLAIM_LOCKED, &zone->flags);