mm: vmscan: move call to shrink_slab() to shrink_zones()

This reduces the indentation level of do_try_to_free_pages() and removes
extra loop over all eligible zones counting the number of on-LRU pages.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Reviewed-by: Glauber Costa <glommer@gmail.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Cc: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 4acee0f..73d6fa7 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2291,13 +2291,16 @@ static inline bool compaction_ready(struct zone *zone, struct scan_control *sc)
  * the caller that it should consider retrying the allocation instead of
  * further reclaim.
  */
-static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
+static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc,
+                        struct shrink_control *shrink)
 {
        struct zoneref *z;
        struct zone *zone;
        unsigned long nr_soft_reclaimed;
        unsigned long nr_soft_scanned;
+       unsigned long lru_pages = 0;
        bool aborted_reclaim = false;
+       struct reclaim_state *reclaim_state = current->reclaim_state;
 
        /*
         * If the number of buffer_heads in the machine exceeds the maximum
@@ -2307,6 +2310,8 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
        if (buffer_heads_over_limit)
                sc->gfp_mask |= __GFP_HIGHMEM;
 
+       nodes_clear(shrink->nodes_to_scan);
+
        for_each_zone_zonelist_nodemask(zone, z, zonelist,
                                        gfp_zone(sc->gfp_mask), sc->nodemask) {
                if (!populated_zone(zone))
@@ -2318,6 +2323,10 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
                if (global_reclaim(sc)) {
                        if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
                                continue;
+
+                       lru_pages += zone_reclaimable_pages(zone);
+                       node_set(zone_to_nid(zone), shrink->nodes_to_scan);
+
                        if (sc->priority != DEF_PRIORITY &&
                            !zone_reclaimable(zone))
                                continue;       /* Let kswapd poll it */
@@ -2354,6 +2363,20 @@ static bool shrink_zones(struct zonelist *zonelist, struct scan_control *sc)
                shrink_zone(zone, sc);
        }
 
+       /*
+        * Don't shrink slabs when reclaiming memory from over limit cgroups
+        * but do shrink slab at least once when aborting reclaim for
+        * compaction to avoid unevenly scanning file/anon LRU pages over slab
+        * pages.
+        */
+       if (global_reclaim(sc)) {
+               shrink_slab(shrink, sc->nr_scanned, lru_pages);
+               if (reclaim_state) {
+                       sc->nr_reclaimed += reclaim_state->reclaimed_slab;
+                       reclaim_state->reclaimed_slab = 0;
+               }
+       }
+
        return aborted_reclaim;
 }
 
@@ -2398,9 +2421,6 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
                                        struct shrink_control *shrink)
 {
        unsigned long total_scanned = 0;
-       struct reclaim_state *reclaim_state = current->reclaim_state;
-       struct zoneref *z;
-       struct zone *zone;
        unsigned long writeback_threshold;
        bool aborted_reclaim;
 
@@ -2413,34 +2433,8 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
                vmpressure_prio(sc->gfp_mask, sc->target_mem_cgroup,
                                sc->priority);
                sc->nr_scanned = 0;
-               aborted_reclaim = shrink_zones(zonelist, sc);
-
-               /*
-                * Don't shrink slabs when reclaiming memory from over limit
-                * cgroups but do shrink slab at least once when aborting
-                * reclaim for compaction to avoid unevenly scanning file/anon
-                * LRU pages over slab pages.
-                */
-               if (global_reclaim(sc)) {
-                       unsigned long lru_pages = 0;
-
-                       nodes_clear(shrink->nodes_to_scan);
-                       for_each_zone_zonelist_nodemask(zone, z, zonelist,
-                                       gfp_zone(sc->gfp_mask), sc->nodemask) {
-                               if (!cpuset_zone_allowed_hardwall(zone, GFP_KERNEL))
-                                       continue;
-
-                               lru_pages += zone_reclaimable_pages(zone);
-                               node_set(zone_to_nid(zone),
-                                        shrink->nodes_to_scan);
-                       }
+               aborted_reclaim = shrink_zones(zonelist, sc, shrink);
 
-                       shrink_slab(shrink, sc->nr_scanned, lru_pages);
-                       if (reclaim_state) {
-                               sc->nr_reclaimed += reclaim_state->reclaimed_slab;
-                               reclaim_state->reclaimed_slab = 0;
-                       }
-               }
                total_scanned += sc->nr_scanned;
                if (sc->nr_reclaimed >= sc->nr_to_reclaim)
                        goto out;