On 10.02.2021 02:33, Yang Shi wrote:

On Tue, Feb 9, 2021 at 12:50 PM Roman Gushchin [off-list ref] wrote:

quoted

On Tue, Feb 09, 2021 at 09:46:39AM -0800, Yang Shi wrote:

quoted

The following patch is going to add nr_deferred into shrinker_map, the change will
make shrinker_map not only include map anymore, so rename it to "memcg_shrinker_info".
And this should make the patch adding nr_deferred cleaner and readable and make
review easier.  Also remove the "memcg_" prefix.

Acked-by: Vlastimil Babka <redacted>
Acked-by: Kirill Tkhai <redacted>
Signed-off-by: Yang Shi <redacted>
---
 include/linux/memcontrol.h |  8 ++---
 mm/memcontrol.c            |  6 ++--
 mm/vmscan.c                | 62 +++++++++++++++++++-------------------
 3 files changed, 38 insertions(+), 38 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 1739f17e0939..4c9253896e25 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h

@@ -96,7 +96,7 @@ struct lruvec_stat {
  * Bitmap of shrinker::id corresponding to memcg-aware shrinkers,
  * which have elements charged to this memcg.
  */
-struct memcg_shrinker_map {
+struct shrinker_info {
      struct rcu_head rcu;
      unsigned long map[];
 };

@@ -118,7 +118,7 @@ struct mem_cgroup_per_node {

      struct mem_cgroup_reclaim_iter  iter;

-     struct memcg_shrinker_map __rcu *shrinker_map;
+     struct shrinker_info __rcu      *shrinker_info;

Nice!

I really like how it looks now in comparison to the v1. Thank you for
working on it!

Thanks a lot for all the great comments from all of you.

quoted

quoted

      struct rb_node          tree_node;      /* RB tree node */
      unsigned long           usage_in_excess;/* Set to the value by which */

@@ -1581,8 +1581,8 @@ static inline bool mem_cgroup_under_socket_pressure(struct mem_cgroup *memcg)
      return false;
 }

-int alloc_shrinker_maps(struct mem_cgroup *memcg);
-void free_shrinker_maps(struct mem_cgroup *memcg);
+int alloc_shrinker_info(struct mem_cgroup *memcg);
+void free_shrinker_info(struct mem_cgroup *memcg);
 void set_shrinker_bit(struct mem_cgroup *memcg, int nid, int shrinker_id);
 #else
 #define mem_cgroup_sockets_enabled 0

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f5c9a0d2160b..f64ad0d044d9 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c

@@ -5246,11 +5246,11 @@ static int mem_cgroup_css_online(struct cgroup_subsys_state *css)
      struct mem_cgroup *memcg = mem_cgroup_from_css(css);

      /*
-      * A memcg must be visible for expand_shrinker_maps()
+      * A memcg must be visible for expand_shrinker_info()
       * by the time the maps are allocated. So, we allocate maps
       * here, when for_each_mem_cgroup() can't skip it.
       */
-     if (alloc_shrinker_maps(memcg)) {
+     if (alloc_shrinker_info(memcg)) {
              mem_cgroup_id_remove(memcg);
              return -ENOMEM;
      }

@@ -5314,7 +5314,7 @@ static void mem_cgroup_css_free(struct cgroup_subsys_state *css)
      vmpressure_cleanup(&memcg->vmpressure);
      cancel_work_sync(&memcg->high_work);
      mem_cgroup_remove_from_trees(memcg);
-     free_shrinker_maps(memcg);
+     free_shrinker_info(memcg);
      memcg_free_kmem(memcg);
      mem_cgroup_free(memcg);
 }

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 641077b09e5d..9436f9246d32 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c

@@ -190,20 +190,20 @@ static int shrinker_nr_max;
 #define NR_MAX_TO_SHR_MAP_SIZE(nr_max) \
      (DIV_ROUND_UP(nr_max, BITS_PER_LONG) * sizeof(unsigned long))

-static void free_shrinker_map_rcu(struct rcu_head *head)
+static void free_shrinker_info_rcu(struct rcu_head *head)
 {
-     kvfree(container_of(head, struct memcg_shrinker_map, rcu));
+     kvfree(container_of(head, struct shrinker_info, rcu));
 }

-static int expand_one_shrinker_map(struct mem_cgroup *memcg,
+static int expand_one_shrinker_info(struct mem_cgroup *memcg,
                                 int size, int old_size)
 {
-     struct memcg_shrinker_map *new, *old;
+     struct shrinker_info *new, *old;
      int nid;

      for_each_node(nid) {
              old = rcu_dereference_protected(
-                     mem_cgroup_nodeinfo(memcg, nid)->shrinker_map, true);
+                     mem_cgroup_nodeinfo(memcg, nid)->shrinker_info, true);
              /* Not yet online memcg */
              if (!old)
                      return 0;

@@ -216,17 +216,17 @@ static int expand_one_shrinker_map(struct mem_cgroup *memcg,
              memset(new->map, (int)0xff, old_size);
              memset((void *)new->map + old_size, 0, size - old_size);

-             rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_map, new);
-             call_rcu(&old->rcu, free_shrinker_map_rcu);
+             rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_info, new);
+             call_rcu(&old->rcu, free_shrinker_info_rcu);

Why not use kvfree_rcu() and get rid of free_shrinker_info_rcu() callback?

Just because this patch is aimed to rename the structure. I think it
may be more preferred to have the cleanup in a separate patch?

I'd voted for a separate patch