mm/vmscan.c: generalize shrink_slab() calls in shrink_node()

The patch makes shrink_slab() be called for root_mem_cgroup in the same
way as it's called for the rest of cgroups.  This simplifies the logic
and improves the readability.

[[email protected]: wrote changelog]
Link: http://lkml.kernel.org/r/153063068338.1818.11496084754797453962.stgit@localhost.localdomain
Signed-off-by: Vladimir Davydov <[email protected]>
Signed-off-by: Kirill Tkhai <[email protected]>
Tested-by: Shakeel Butt <[email protected]>
Cc: Al Viro <[email protected]>
Cc: Andrey Ryabinin <[email protected]>
Cc: Chris Wilson <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Guenter Roeck <[email protected]>
Cc: "Huang, Ying" <[email protected]>
Cc: Johannes Weiner <[email protected]>
Cc: Josef Bacik <[email protected]>
Cc: Li RongQing <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Matthias Kaehlcke <[email protected]>
Cc: Mel Gorman <[email protected]>
Cc: Michal Hocko <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: Philippe Ombredanne <[email protected]>
Cc: Roman Gushchin <[email protected]>
Cc: Sahitya Tummala <[email protected]>
Cc: Stephen Rothwell <[email protected]>
Cc: Tetsuo Handa <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Waiman Long <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

diff --git a/mm/vmscan.c b/mm/vmscan.c
index d7a5b856686971ac4192a7e3e80907db1adc6036..2aa3cb760189a936a55ce1b400af84ced0a23647 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -627,10 +627,8 @@ static unsigned long shrink_slab_memcg(gfp_t gfp_mask, int nid,
  * @nid is passed along to shrinkers with SHRINKER_NUMA_AWARE set,
  * unaware shrinkers will receive a node id of 0 instead.
  *
- * @memcg specifies the memory cgroup to target. If it is not NULL,
- * only shrinkers with SHRINKER_MEMCG_AWARE set will be called to scan
- * objects from the memory cgroup specified. Otherwise, only unaware
- * shrinkers are called.
+ * @memcg specifies the memory cgroup to target. Unaware shrinkers
+ * are called only if it is the root cgroup.
  *
  * @priority is sc->priority, we take the number of objects and >> by priority
  * in order to get the scan target.
@@ -644,7 +642,7 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
        struct shrinker *shrinker;
        unsigned long freed = 0;
 
-       if (memcg && !mem_cgroup_is_root(memcg))
+       if (!mem_cgroup_is_root(memcg))
                return shrink_slab_memcg(gfp_mask, nid, memcg, priority);
 
        if (!down_read_trylock(&shrinker_rwsem))
@@ -657,9 +655,6 @@ static unsigned long shrink_slab(gfp_t gfp_mask, int nid,
                        .memcg = memcg,
                };
 
-               if (!!memcg != !!(shrinker->flags & SHRINKER_MEMCG_AWARE))
-                       continue;
-
                if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
                        sc.nid = 0;
 
@@ -689,6 +684,7 @@ void drop_slab_node(int nid)
                struct mem_cgroup *memcg = NULL;
 
                freed = 0;
+               memcg = mem_cgroup_iter(NULL, NULL, NULL);
                do {
                        freed += shrink_slab(GFP_KERNEL, nid, memcg, 0);
                } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);
@@ -2708,9 +2704,8 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
                        shrink_node_memcg(pgdat, memcg, sc, &lru_pages);
                        node_lru_pages += lru_pages;
 
-                       if (memcg)
-                               shrink_slab(sc->gfp_mask, pgdat->node_id,
-                                           memcg, sc->priority);
+                       shrink_slab(sc->gfp_mask, pgdat->node_id,
+                                   memcg, sc->priority);
 
                        /* Record the group's reclaim efficiency */
                        vmpressure(sc->gfp_mask, memcg, false,
@@ -2734,10 +2729,6 @@ static bool shrink_node(pg_data_t *pgdat, struct scan_control *sc)
                        }
                } while ((memcg = mem_cgroup_iter(root, memcg, &reclaim)));
 
-               if (global_reclaim(sc))
-                       shrink_slab(sc->gfp_mask, pgdat->node_id, NULL,
-                                   sc->priority);
-
                if (reclaim_state) {
                        sc->nr_reclaimed += reclaim_state->reclaimed_slab;
                        reclaim_state->reclaimed_slab = 0;