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, 9 insertions, 13 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index bc0f8db8340f..5cbf64dd79c1 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1699,8 +1699,7 @@ static void shrink_zones(int priority, struct zonelist *zonelist,
                                 continue;
                         note_zone_scanning_priority(zone, priority);
 
-                        if (zone_is_all_unreclaimable(zone) &&
-                                                priority != DEF_PRIORITY)
+                        if (zone->all_unreclaimable && priority != DEF_PRIORITY)
                                 continue;       /* Let kswapd poll it */
                         sc->all_unreclaimable = 0;
                 } else {
@@ -1927,7 +1926,7 @@ static int sleeping_prematurely(pg_data_t *pgdat, int order, long remaining)
                 if (!populated_zone(zone))
                         continue;
 
-                if (zone_is_all_unreclaimable(zone))
+                if (zone->all_unreclaimable)
                         continue;
 
                 if (!zone_watermark_ok(zone, order, high_wmark_pages(zone),
@@ -2017,8 +2016,7 @@ loop_again:
                         if (!populated_zone(zone))
                                 continue;
 
-                        if (zone_is_all_unreclaimable(zone) &&
-                            priority != DEF_PRIORITY)
+                        if (zone->all_unreclaimable && priority != DEF_PRIORITY)
                                 continue;
 
                         /*
@@ -2061,8 +2059,7 @@ loop_again:
                         if (!populated_zone(zone))
                                 continue;
 
-                        if (zone_is_all_unreclaimable(zone) &&
-                                        priority != DEF_PRIORITY)
+                        if (zone->all_unreclaimable && priority != DEF_PRIORITY)
                                 continue;
 
                         temp_priority[i] = priority;
@@ -2089,12 +2086,11 @@ loop_again:
                                                 lru_pages);
                         sc.nr_reclaimed += reclaim_state->reclaimed_slab;
                         total_scanned += sc.nr_scanned;
-                        if (zone_is_all_unreclaimable(zone))
+                        if (zone->all_unreclaimable)
                                 continue;
-                        if (nr_slab == 0 && zone->pages_scanned >=
-                                        (zone_reclaimable_pages(zone) * 6))
-                                        zone_set_flag(zone,
-                                                      ZONE_ALL_UNRECLAIMABLE);
+                        if (nr_slab == 0 &&
+                            zone->pages_scanned >= (zone_reclaimable_pages(zone) * 6))
+                                zone->all_unreclaimable = 1;
                         /*
                          * If we've done a decent amount of scanning and
                          * the reclaim ratio is low, start doing writepage
@@ -2624,7 +2620,7 @@ int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
             zone_page_state(zone, NR_SLAB_RECLAIMABLE) <= zone->min_slab_pages)
                 return ZONE_RECLAIM_FULL;
 
-        if (zone_is_all_unreclaimable(zone))
+        if (zone->all_unreclaimable)
                 return ZONE_RECLAIM_FULL;
 
         /*