oom: change all_unreclaimable zone member to flags

Convert the int all_unreclaimable member of struct zone to unsigned long
flags.  This can now be used to specify several different zone flags such as
all_unreclaimable and reclaim_in_progress, which can now be removed and
converted to a per-zone flag.

Flags are set and cleared as follows:

	zone_set_flag(struct zone *zone, zone_flags_t flag)
	zone_clear_flag(struct zone *zone, zone_flags_t flag)

Defines the first zone flags, ZONE_ALL_UNRECLAIMABLE and ZONE_RECLAIM_LOCKED,
which have the same semantics as the old zone->all_unreclaimable and
zone->reclaim_in_progress, respectively.  Also converts all current users that
set or clear either flag to use the new interface.

Helper functions are defined to test the flags:

	int zone_is_all_unreclaimable(const struct zone *zone)
	int zone_is_reclaim_locked(const struct zone *zone)

All flag operators are of the atomic variety because there are currently
readers that are implemented that do not take zone->lock.

[akpm@linux-foundation.org: add needed include]
Cc: Andrea Arcangeli <andrea@suse.de>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 13 insertions, 12 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index bbd194630c5b..d8893dc2d4eb 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1108,7 +1108,7 @@ static unsigned long shrink_zone(int priority, struct zone *zone,
         unsigned long nr_to_scan;
         unsigned long nr_reclaimed = 0;
 
-        atomic_inc(&zone->reclaim_in_progress);
+        zone_set_flag(zone, ZONE_RECLAIM_LOCKED);
 
         /*
          * Add one to `nr_to_scan' just to make sure that the kernel will
@@ -1149,7 +1149,7 @@ static unsigned long shrink_zone(int priority, struct zone *zone,
 
         throttle_vm_writeout(sc->gfp_mask);
 
-        atomic_dec(&zone->reclaim_in_progress);
+        zone_clear_flag(zone, ZONE_RECLAIM_LOCKED);
         return nr_reclaimed;
 }
 
@@ -1187,7 +1187,7 @@ static unsigned long shrink_zones(int priority, struct zone **zones,
 
                 note_zone_scanning_priority(zone, priority);
 
-                if (zone->all_unreclaimable && priority != DEF_PRIORITY)
+                if (zone_is_all_unreclaimable(zone) && priority != DEF_PRIORITY)
                         continue;       /* Let kswapd poll it */
 
                 sc->all_unreclaimable = 0;
@@ -1368,7 +1368,8 @@ loop_again:
                         if (!populated_zone(zone))
                                 continue;
 
-                        if (zone->all_unreclaimable && priority != DEF_PRIORITY)
+                        if (zone_is_all_unreclaimable(zone) &&
+                            priority != DEF_PRIORITY)
                                 continue;
 
                         if (!zone_watermark_ok(zone, order, zone->pages_high,
@@ -1403,7 +1404,8 @@ loop_again:
                         if (!populated_zone(zone))
                                 continue;
 
-                        if (zone->all_unreclaimable && priority != DEF_PRIORITY)
+                        if (zone_is_all_unreclaimable(zone) &&
+                                        priority != DEF_PRIORITY)
                                 continue;
 
                         if (!zone_watermark_ok(zone, order, zone->pages_high,
@@ -1424,12 +1426,13 @@ loop_again:
                                                 lru_pages);
                         nr_reclaimed += reclaim_state->reclaimed_slab;
                         total_scanned += sc.nr_scanned;
-                        if (zone->all_unreclaimable)
+                        if (zone_is_all_unreclaimable(zone))
                                 continue;
                         if (nr_slab == 0 && zone->pages_scanned >=
                                 (zone_page_state(zone, NR_ACTIVE)
                                 + zone_page_state(zone, NR_INACTIVE)) * 6)
-                                        zone->all_unreclaimable = 1;
+                                        zone_set_flag(zone,
+                                                      ZONE_ALL_UNRECLAIMABLE);
                         /*
                          * If we've done a decent amount of scanning and
                          * the reclaim ratio is low, start doing writepage
@@ -1595,7 +1598,7 @@ static unsigned long shrink_all_zones(unsigned long nr_pages, int prio,
                 if (!populated_zone(zone))
                         continue;
 
-                if (zone->all_unreclaimable && prio != DEF_PRIORITY)
+                if (zone_is_all_unreclaimable(zone) && prio != DEF_PRIORITY)
                         continue;
 
                 /* For pass = 0 we don't shrink the active list */
@@ -1919,10 +1922,8 @@ int zone_reclaim(struct zone *zone, gfp_t gfp_mask, unsigned int order)
          * not have reclaimable pages and if we should not delay the allocation
          * then do not scan.
          */
-        if (!(gfp_mask & __GFP_WAIT) ||
-                zone->all_unreclaimable ||
-                atomic_read(&zone->reclaim_in_progress) > 0 ||
-                (current->flags & PF_MEMALLOC))
+        if (!(gfp_mask & __GFP_WAIT) || zone_is_all_unreclaimable(zone) ||
+                zone_is_reclaim_locked(zone) || (current->flags & PF_MEMALLOC))
                         return 0;
 
         /*