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, 25 insertions, 4 deletions

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index f4bfe82..bad9486 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