mm: vmscan: use per memcg nr_deferred of shrinker

Use per memcg's nr_deferred for memcg aware shrinkers.  The shrinker's
nr_deferred will be used in the following cases:

    1. Non memcg aware shrinkers
    2. !CONFIG_MEMCG
    3. memcg is disabled by boot parameter

Link: https://lkml.kernel.org/r/20210311190845.9708-11-shy828301@gmail.com
Signed-off-by: Yang Shi <shy828301@gmail.com>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
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 db668c4..19b134d 100644 (file)
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -376,6 +376,24 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker)
        idr_remove(&shrinker_idr, id);
 }
 
+static long xchg_nr_deferred_memcg(int nid, struct shrinker *shrinker,
+                                  struct mem_cgroup *memcg)
+{
+       struct shrinker_info *info;
+
+       info = shrinker_info_protected(memcg, nid);
+       return atomic_long_xchg(&info->nr_deferred[shrinker->id], 0);
+}
+
+static long add_nr_deferred_memcg(long nr, int nid, struct shrinker *shrinker,
+                                 struct mem_cgroup *memcg)
+{
+       struct shrinker_info *info;
+
+       info = shrinker_info_protected(memcg, nid);
+       return atomic_long_add_return(nr, &info->nr_deferred[shrinker->id]);
+}
+
 static bool cgroup_reclaim(struct scan_control *sc)
 {
        return sc->target_mem_cgroup;
@@ -414,6 +432,18 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker)
 {
 }
 
+static long xchg_nr_deferred_memcg(int nid, struct shrinker *shrinker,
+                                  struct mem_cgroup *memcg)
+{
+       return 0;
+}
+
+static long add_nr_deferred_memcg(long nr, int nid, struct shrinker *shrinker,
+                                 struct mem_cgroup *memcg)
+{
+       return 0;
+}
+
 static bool cgroup_reclaim(struct scan_control *sc)
 {
        return false;
@@ -425,6 +455,39 @@ static bool writeback_throttling_sane(struct scan_control *sc)
 }
 #endif
 
+static long xchg_nr_deferred(struct shrinker *shrinker,
+                            struct shrink_control *sc)
+{
+       int nid = sc->nid;
+
+       if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
+               nid = 0;
+
+       if (sc->memcg &&
+           (shrinker->flags & SHRINKER_MEMCG_AWARE))
+               return xchg_nr_deferred_memcg(nid, shrinker,
+                                             sc->memcg);
+
+       return atomic_long_xchg(&shrinker->nr_deferred[nid], 0);
+}
+
+
+static long add_nr_deferred(long nr, struct shrinker *shrinker,
+                           struct shrink_control *sc)
+{
+       int nid = sc->nid;
+
+       if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
+               nid = 0;
+
+       if (sc->memcg &&
+           (shrinker->flags & SHRINKER_MEMCG_AWARE))
+               return add_nr_deferred_memcg(nr, nid, shrinker,
+                                            sc->memcg);
+
+       return atomic_long_add_return(nr, &shrinker->nr_deferred[nid]);
+}
+
 /*
  * This misses isolated pages which are not accounted for to save counters.
  * As the data only determines if reclaim or compaction continues, it is
@@ -561,14 +624,10 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
        long freeable;
        long nr;
        long new_nr;
-       int nid = shrinkctl->nid;
        long batch_size = shrinker->batch ? shrinker->batch
                                          : SHRINK_BATCH;
        long scanned = 0, next_deferred;
 
-       if (!(shrinker->flags & SHRINKER_NUMA_AWARE))
-               nid = 0;
-
        freeable = shrinker->count_objects(shrinker, shrinkctl);
        if (freeable == 0 || freeable == SHRINK_EMPTY)
                return freeable;
@@ -578,7 +637,7 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
         * and zero it so that other concurrent shrinker invocations
         * don't also do this scanning work.
         */
-       nr = atomic_long_xchg(&shrinker->nr_deferred[nid], 0);
+       nr = xchg_nr_deferred(shrinker, shrinkctl);
 
        total_scan = nr;
        if (shrinker->seeks) {
@@ -669,14 +728,9 @@ static unsigned long do_shrink_slab(struct shrink_control *shrinkctl,
                next_deferred = 0;
        /*
         * move the unused scan count back into the shrinker in a
-        * manner that handles concurrent updates. If we exhausted the
-        * scan, there is no need to do an update.
+        * manner that handles concurrent updates.
         */
-       if (next_deferred > 0)
-               new_nr = atomic_long_add_return(next_deferred,
-                                               &shrinker->nr_deferred[nid]);
-       else
-               new_nr = atomic_long_read(&shrinker->nr_deferred[nid]);
+       new_nr = add_nr_deferred(next_deferred, shrinker, shrinkctl);
 
        trace_mm_shrink_slab_end(shrinker, shrinkctl->nid, freed, nr, new_nr, total_scan);
        return freed;