[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>

1 files changed, 16 insertions, 17 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 40fea4918390..7430df68cb64 100644
--- 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;