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>

4 files changed, 43 insertions, 21 deletions

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index f4bfe824834f..bad9486ee0cc 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -7,6 +7,7 @@
 #include <linux/spinlock.h>
 #include <linux/list.h>
 #include <linux/wait.h>
+#include <linux/bitops.h>
 #include <linux/cache.h>
 #include <linux/threads.h>
 #include <linux/numa.h>
@@ -262,10 +263,7 @@ struct zone {
         unsigned long           nr_scan_active;
         unsigned long           nr_scan_inactive;
         unsigned long           pages_scanned;     /* since last reclaim */
-        int                     all_unreclaimable; /* All pages pinned */
-
-        /* A count of how many reclaimers are scanning this zone */
-        atomic_t                reclaim_in_progress;
+        unsigned long           flags;             /* zone flags, see below */
 
         /* Zone statistics */
         atomic_long_t           vm_stat[NR_VM_ZONE_STAT_ITEMS];
@@ -343,6 +341,29 @@ struct zone {
         const char              *name;
 } ____cacheline_internodealigned_in_smp;
 
+typedef enum {
+        ZONE_ALL_UNRECLAIMABLE,         /* all pages pinned */
+        ZONE_RECLAIM_LOCKED,            /* prevents concurrent reclaim */
+} zone_flags_t;
+
+static inline void zone_set_flag(struct zone *zone, zone_flags_t flag)
+{
+        set_bit(flag, &zone->flags);
+}
+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);
+}
+
 /*
  * The "priority" of VM scanning is how much of the queues we will scan in one
  * go. A value of 12 for DEF_PRIORITY implies that we will scan 1/4096th of the
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 0e3a05fd4734..fd2df29cc645 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -490,7 +490,7 @@ static void free_pages_bulk(struct zone *zone, int count,
                                         struct list_head *list, int order)
 {
         spin_lock(&zone->lock);
-        zone->all_unreclaimable = 0;
+        zone_clear_flag(zone, ZONE_ALL_UNRECLAIMABLE);
         zone->pages_scanned = 0;
         while (count--) {
                 struct page *page;
@@ -507,7 +507,7 @@ static void free_pages_bulk(struct zone *zone, int count,
 static void free_one_page(struct zone *zone, struct page *page, int order)
 {
         spin_lock(&zone->lock);
-        zone->all_unreclaimable = 0;
+        zone_clear_flag(zone, ZONE_ALL_UNRECLAIMABLE);
         zone->pages_scanned = 0;
         __free_one_page(page, zone, order);
         spin_unlock(&zone->lock);
@@ -1851,7 +1851,7 @@ void show_free_areas(void)
                         K(zone_page_state(zone, NR_INACTIVE)),
                         K(zone->present_pages),
                         zone->pages_scanned,
-                        (zone->all_unreclaimable ? "yes" : "no")
+                        (zone_is_all_unreclaimable(zone) ? "yes" : "no")
                         );
                 printk("lowmem_reserve[]:");
                 for (i = 0; i < MAX_NR_ZONES; i++)
@@ -3372,7 +3372,7 @@ static void __meminit free_area_init_core(struct pglist_data *pgdat,
                 zone->nr_scan_active = 0;
                 zone->nr_scan_inactive = 0;
                 zap_zone_vm_stats(zone);
-                atomic_set(&zone->reclaim_in_progress, 0);
+                zone->flags = 0;
                 if (!size)
                         continue;
 
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;
 
         /*
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 3b5e9043e7db..4651bf153f35 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -704,7 +704,7 @@ static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
                    "\n  all_unreclaimable: %u"
                    "\n  prev_priority:     %i"
                    "\n  start_pfn:         %lu",
-                   zone->all_unreclaimable,
+                           zone_is_all_unreclaimable(zone),
                    zone->prev_priority,
                    zone->zone_start_pfn);
         seq_putc(m, '\n');