mm: shrink_all_memory(): use sc.nr_reclaimed

Commit a79311c14eae4bb946a97af25f3e1b17d625985d "vmscan: bail out of
direct reclaim after swap_cluster_max pages" moved the nr_reclaimed
counter into the scan control to accumulate the number of all reclaimed
pages in a reclaim invocation.

shrink_all_memory() can use the same mechanism. it increase code
consistency and redability.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: MinChan Kim <minchan.kim@gmail.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 24 insertions, 22 deletions

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 301f057fd115..b15dcbb9e174 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2050,16 +2050,15 @@ unsigned long global_lru_pages(void)
 #ifdef CONFIG_PM
 /*
  * Helper function for shrink_all_memory().  Tries to reclaim 'nr_pages' pages
- * from LRU lists system-wide, for given pass and priority, and returns the
- * number of reclaimed pages
+ * from LRU lists system-wide, for given pass and priority.
  *
  * For pass > 3 we also try to shrink the LRU lists that contain a few pages
  */
-static unsigned long shrink_all_zones(unsigned long nr_pages, int prio,
+static void shrink_all_zones(unsigned long nr_pages, int prio,
                                       int pass, struct scan_control *sc)
 {
         struct zone *zone;
-        unsigned long ret = 0;
+        unsigned long nr_reclaimed = 0;
 
         for_each_populated_zone(zone) {
                 enum lru_list l;
@@ -2082,14 +2081,16 @@ static unsigned long shrink_all_zones(unsigned long nr_pages, int prio,
 
                                 zone->lru[l].nr_scan = 0;
                                 nr_to_scan = min(nr_pages, lru_pages);
-                                ret += shrink_list(l, nr_to_scan, zone,
+                                nr_reclaimed += shrink_list(l, nr_to_scan, zone,
                                                                 sc, prio);
-                                if (ret >= nr_pages)
-                                        return ret;
+                                if (nr_reclaimed >= nr_pages) {
+                                        sc->nr_reclaimed = nr_reclaimed;
+                                        return;
+                                }
                         }
                 }
         }
-        return ret;
+        sc->nr_reclaimed = nr_reclaimed;
 }
 
 /*
@@ -2103,7 +2104,6 @@ static unsigned long shrink_all_zones(unsigned long nr_pages, int prio,
 unsigned long shrink_all_memory(unsigned long nr_pages)
 {
         unsigned long lru_pages, nr_slab;
-        unsigned long ret = 0;
         int pass;
         struct reclaim_state reclaim_state;
         struct scan_control sc = {
@@ -2125,8 +2125,8 @@ unsigned long shrink_all_memory(unsigned long nr_pages)
                 if (!reclaim_state.reclaimed_slab)
                         break;
 
-                ret += reclaim_state.reclaimed_slab;
-                if (ret >= nr_pages)
+                sc.nr_reclaimed += reclaim_state.reclaimed_slab;
+                if (sc.nr_reclaimed >= nr_pages)
                         goto out;
 
                 nr_slab -= reclaim_state.reclaimed_slab;
@@ -2148,18 +2148,18 @@ unsigned long shrink_all_memory(unsigned long nr_pages)
                         sc.may_unmap = 1;
 
                 for (prio = DEF_PRIORITY; prio >= 0; prio--) {
-                        unsigned long nr_to_scan = nr_pages - ret;
+                        unsigned long nr_to_scan = nr_pages - sc.nr_reclaimed;
 
                         sc.nr_scanned = 0;
-                        ret += shrink_all_zones(nr_to_scan, prio, pass, &sc);
-                        if (ret >= nr_pages)
+                        shrink_all_zones(nr_to_scan, prio, pass, &sc);
+                        if (sc.nr_reclaimed >= nr_pages)
                                 goto out;
 
                         reclaim_state.reclaimed_slab = 0;
                         shrink_slab(sc.nr_scanned, sc.gfp_mask,
                                         global_lru_pages());
-                        ret += reclaim_state.reclaimed_slab;
-                        if (ret >= nr_pages)
+                        sc.nr_reclaimed += reclaim_state.reclaimed_slab;
+                        if (sc.nr_reclaimed >= nr_pages)
                                 goto out;
 
                         if (sc.nr_scanned && prio < DEF_PRIORITY - 2)
@@ -2168,21 +2168,23 @@ unsigned long shrink_all_memory(unsigned long nr_pages)
         }
 
         /*
-         * If ret = 0, we could not shrink LRUs, but there may be something
-         * in slab caches
+         * If sc.nr_reclaimed = 0, we could not shrink LRUs, but there may be
+         * something in slab caches
          */
-        if (!ret) {
+        if (!sc.nr_reclaimed) {
                 do {
                         reclaim_state.reclaimed_slab = 0;
                         shrink_slab(nr_pages, sc.gfp_mask, global_lru_pages());
-                        ret += reclaim_state.reclaimed_slab;
-                } while (ret < nr_pages && reclaim_state.reclaimed_slab > 0);
+                        sc.nr_reclaimed += reclaim_state.reclaimed_slab;
+                } while (sc.nr_reclaimed < nr_pages &&
+                                reclaim_state.reclaimed_slab > 0);
         }
 
+
 out:
         current->reclaim_state = NULL;
 
-        return ret;
+        return sc.nr_reclaimed;
 }
 #endif