vmscan: protect reading of reclaim_stat with lru_lock
[sfrench/cifs-2.6.git] / mm / vmscan.c
index 1b4e4a597caa0a1a1b90f07cc940c0cf6801a5c9..a3d669f8e25ec2a96b7ea9925c2618971e2208df 100644 (file)
@@ -1627,6 +1627,13 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc,
                }
        }
 
+       /*
+        * With swappiness at 100, anonymous and file have the same priority.
+        * This scanning priority is essentially the inverse of IO cost.
+        */
+       anon_prio = sc->swappiness;
+       file_prio = 200 - sc->swappiness;
+
        /*
         * OK, so we have swap space and a fair amount of page cache
         * pages.  We use the recently rotated / recently scanned
@@ -1638,27 +1645,17 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc,
         *
         * anon in [0], file in [1]
         */
+       spin_lock_irq(&zone->lru_lock);
        if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) {
-               spin_lock_irq(&zone->lru_lock);
                reclaim_stat->recent_scanned[0] /= 2;
                reclaim_stat->recent_rotated[0] /= 2;
-               spin_unlock_irq(&zone->lru_lock);
        }
 
        if (unlikely(reclaim_stat->recent_scanned[1] > file / 4)) {
-               spin_lock_irq(&zone->lru_lock);
                reclaim_stat->recent_scanned[1] /= 2;
                reclaim_stat->recent_rotated[1] /= 2;
-               spin_unlock_irq(&zone->lru_lock);
        }
 
-       /*
-        * With swappiness at 100, anonymous and file have the same priority.
-        * This scanning priority is essentially the inverse of IO cost.
-        */
-       anon_prio = sc->swappiness;
-       file_prio = 200 - sc->swappiness;
-
        /*
         * The amount of pressure on anon vs file pages is inversely
         * proportional to the fraction of recently scanned pages on
@@ -1669,6 +1666,7 @@ static void get_scan_count(struct zone *zone, struct scan_control *sc,
 
        fp = (file_prio + 1) * (reclaim_stat->recent_scanned[1] + 1);
        fp /= reclaim_stat->recent_rotated[1] + 1;
+       spin_unlock_irq(&zone->lru_lock);
 
        fraction[0] = ap;
        fraction[1] = fp;