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, 3 insertions, 3 deletions

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 80bcee0c5034..0734bedabd9c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -530,7 +530,7 @@ static void free_pcppages_bulk(struct zone *zone, int count,
         int batch_free = 0;
 
         spin_lock(&zone->lock);
-        zone_clear_flag(zone, ZONE_ALL_UNRECLAIMABLE);
+        zone->all_unreclaimable = 0;
         zone->pages_scanned = 0;
 
         __mod_zone_page_state(zone, NR_FREE_PAGES, count);
@@ -568,7 +568,7 @@ static void free_one_page(struct zone *zone, struct page *page, int order,
                                 int migratetype)
 {
         spin_lock(&zone->lock);
-        zone_clear_flag(zone, ZONE_ALL_UNRECLAIMABLE);
+        zone->all_unreclaimable = 0;
         zone->pages_scanned = 0;
 
         __mod_zone_page_state(zone, NR_FREE_PAGES, 1 << order);
@@ -2262,7 +2262,7 @@ void show_free_areas(void)
                         K(zone_page_state(zone, NR_BOUNCE)),
                         K(zone_page_state(zone, NR_WRITEBACK_TEMP)),
                         zone->pages_scanned,
-                        (zone_is_all_unreclaimable(zone) ? "yes" : "no")
+                        (zone->all_unreclaimable ? "yes" : "no")
                         );
                 printk("lowmem_reserve[]:");
                 for (i = 0; i < MAX_NR_ZONES; i++)