[PATCH] shrink_all_memory(): fix lru_pages handling

At the end of shrink_all_memory() we forget to recalculate lru_pages: it can
be zero.

Fix that up, and add a helper function for this operation too.

Also, recalculate lru_pages each time around the inner loop to get the
balancing correct.

Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 40fea4918390e6e69b96bc463b974a4ad31bb2bf..7430df68cb64aaf2856c7158920442c77fe1cf27 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1406,6 +1406,16 @@ static unsigned long shrink_all_zones(unsigned long nr_pages, int prio,
        return ret;
 }
 
+static unsigned long count_lru_pages(void)
+{
+       struct zone *zone;
+       unsigned long ret = 0;
+
+       for_each_zone(zone)
+               ret += zone->nr_active + zone->nr_inactive;
+       return ret;
+}
+
 /*
  * Try to free `nr_pages' of memory, system-wide, and return the number of
  * freed pages.
@@ -1420,7 +1430,6 @@ unsigned long shrink_all_memory(unsigned long nr_pages)
        unsigned long ret = 0;
        int pass;
        struct reclaim_state reclaim_state;
-       struct zone *zone;
        struct scan_control sc = {
                .gfp_mask = GFP_KERNEL,
                .may_swap = 0,
@@ -1431,10 +1440,7 @@ unsigned long shrink_all_memory(unsigned long nr_pages)
 
        current->reclaim_state = &reclaim_state;
 
-       lru_pages = 0;
-       for_each_zone(zone)
-               lru_pages += zone->nr_active + zone->nr_inactive;
-
+       lru_pages = count_lru_pages();
        nr_slab = global_page_state(NR_SLAB_RECLAIMABLE);
        /* If slab caches are huge, it's better to hit them first */
        while (nr_slab >= lru_pages) {
@@ -1461,13 +1467,6 @@ unsigned long shrink_all_memory(unsigned long nr_pages)
        for (pass = 0; pass < 5; pass++) {
                int prio;
 
-               /* Needed for shrinking slab caches later on */
-               if (!lru_pages)
-                       for_each_zone(zone) {
-                               lru_pages += zone->nr_active;
-                               lru_pages += zone->nr_inactive;
-                       }
-
                /* Force reclaiming mapped pages in the passes #3 and #4 */
                if (pass > 2) {
                        sc.may_swap = 1;
@@ -1483,7 +1482,8 @@ unsigned long shrink_all_memory(unsigned long nr_pages)
                                goto out;
 
                        reclaim_state.reclaimed_slab = 0;
-                       shrink_slab(sc.nr_scanned, sc.gfp_mask, lru_pages);
+                       shrink_slab(sc.nr_scanned, sc.gfp_mask,
+                                       count_lru_pages());
                        ret += reclaim_state.reclaimed_slab;
                        if (ret >= nr_pages)
                                goto out;
@@ -1491,20 +1491,19 @@ unsigned long shrink_all_memory(unsigned long nr_pages)
                        if (sc.nr_scanned && prio < DEF_PRIORITY - 2)
                                congestion_wait(WRITE, HZ / 10);
                }
-
-               lru_pages = 0;
        }
 
        /*
         * If ret = 0, we could not shrink LRUs, but there may be something
         * in slab caches
         */
-       if (!ret)
+       if (!ret) {
                do {
                        reclaim_state.reclaimed_slab = 0;
-                       shrink_slab(nr_pages, sc.gfp_mask, lru_pages);
+                       shrink_slab(nr_pages, sc.gfp_mask, count_lru_pages());
                        ret += reclaim_state.reclaimed_slab;
                } while (ret < nr_pages && reclaim_state.reclaimed_slab > 0);
+       }
 
 out:
        current->reclaim_state = NULL;