[PATCH -mm v2 4/9] memcg: rename some cache id related variables

[Vladimir Davydov]

memcg_limited_groups_array_size, which defines the size of memcg_caches
arrays, sounds rather cumbersome. Also it doesn't point anyhow that it's
related to kmem/caches stuff. So let's rename it to memcg_max_cache_ids.
It's concise and points us directly to memcg_cache_id.

Also, rename kmem_limited_groups to memcg_cache_ida, because it's not a
container for groups, but the memcg_cache_id allocator.

Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
---
 include/linux/memcontrol.h |    9 +++++++--
 mm/memcontrol.c            |   19 +++++++++----------
 mm/slab_common.c           |    4 ++--
 3 files changed, 18 insertions(+), 14 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index a592fe75192b..e1a894c1018f 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -391,7 +391,12 @@ static inline void sock_release_memcg(struct sock *sk)
 #ifdef CONFIG_MEMCG_KMEM
 extern struct static_key memcg_kmem_enabled_key;
 
-extern int memcg_limited_groups_array_size;
+/*
+ * The maximal number of kmem-active memory cgroups that can exist on the
+ * system. May grow, but never shrinks. The value returned by memcg_cache_id()
+ * is always less.
+ */
+extern int memcg_max_cache_ids;
 
 /*
  * Helper macro to loop through all memcg-specific caches. Callers must still
@@ -399,7 +404,7 @@ extern int memcg_limited_groups_array_size;
  * the slab_mutex must be held when looping through those caches
  */
 #define for_each_memcg_cache_index(_idx)	\
-	for ((_idx) = 0; (_idx) < memcg_limited_groups_array_size; (_idx)++)
+	for ((_idx) = 0; (_idx) < memcg_max_cache_ids; (_idx)++)
 
 static inline bool memcg_kmem_enabled(void)
 {
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index aa7c1d7b0376..fc1e2067a4c4 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -589,12 +589,11 @@ static void disarm_sock_keys(struct mem_cgroup *memcg)
  *  memcgs, and none but the 200th is kmem-limited, we'd have to have a
  *  200 entry array for that.
  *
- * The current size of the caches array is stored in
- * memcg_limited_groups_array_size.  It will double each time we have to
- * increase it.
+ * The current size of the caches array is stored in memcg_max_cache_ids. It
+ * will double each time we have to increase it.
  */
-static DEFINE_IDA(kmem_limited_groups);
-int memcg_limited_groups_array_size;
+static DEFINE_IDA(memcg_cache_ida);
+int memcg_max_cache_ids;
 
 /*
  * MIN_SIZE is different than 1, because we would like to avoid going through
@@ -2588,12 +2587,12 @@ static int memcg_alloc_cache_id(void)
 	int id, size;
 	int err;
 
-	id = ida_simple_get(&kmem_limited_groups,
+	id = ida_simple_get(&memcg_cache_ida,
 			    0, MEMCG_CACHES_MAX_SIZE, GFP_KERNEL);
 	if (id < 0)
 		return id;
 
-	if (id < memcg_limited_groups_array_size)
+	if (id < memcg_max_cache_ids)
 		return id;
 
 	/*
@@ -2612,7 +2611,7 @@ static int memcg_alloc_cache_id(void)
 	mutex_unlock(&memcg_slab_mutex);
 
 	if (err) {
-		ida_simple_remove(&kmem_limited_groups, id);
+		ida_simple_remove(&memcg_cache_ida, id);
 		return err;
 	}
 	return id;
@@ -2620,7 +2619,7 @@ static int memcg_alloc_cache_id(void)
 
 static void memcg_free_cache_id(int id)
 {
-	ida_simple_remove(&kmem_limited_groups, id);
+	ida_simple_remove(&memcg_cache_ida, id);
 }
 
 /*
@@ -2630,7 +2629,7 @@ static void memcg_free_cache_id(int id)
  */
 void memcg_update_array_size(int num)
 {
-	memcg_limited_groups_array_size = num;
+	memcg_max_cache_ids = num;
 }
 
 static void memcg_register_cache(struct mem_cgroup *memcg,
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 406944207b61..41fe0ad199f2 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -116,7 +116,7 @@ static int memcg_alloc_cache_params(struct mem_cgroup *memcg,
 
 	if (!memcg) {
 		size = offsetof(struct memcg_cache_params, memcg_caches);
-		size += memcg_limited_groups_array_size * sizeof(void *);
+		size += memcg_max_cache_ids * sizeof(void *);
 	} else
 		size = sizeof(struct memcg_cache_params);
 
@@ -154,7 +154,7 @@ static int memcg_update_cache_params(struct kmem_cache *s, int num_memcgs)
 
 	cur_params = s->memcg_params;
 	memcpy(new_params->memcg_caches, cur_params->memcg_caches,
-	       memcg_limited_groups_array_size * sizeof(void *));
+	       memcg_max_cache_ids * sizeof(void *));
 
 	new_params->is_root_cache = true;
 
-- 
1.7.10.4

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