memcg: move memcg_{alloc,free}_cache_params to slab_common.c

The only reason why they live in memcontrol.c is that we get/put css
reference to the owner memory cgroup in them.  However, we can do that in
memcg_{un,}register_cache.  OTOH, there are several reasons to move them
to slab_common.c.

First, I think that the less public interface functions we have in
memcontrol.h the better.  Since the functions I move don't depend on
memcontrol, I think it's worth making them private to slab, especially
taking into account that the arrays are defined on the slab's side too.

Second, the way how per-memcg arrays are updated looks rather awkward: it
proceeds from memcontrol.c (__memcg_activate_kmem) to slab_common.c
(memcg_update_all_caches) and back to memcontrol.c again
(memcg_update_array_size).  In the following patches I move the function
relocating the arrays (memcg_update_array_size) to slab_common.c and
therefore get rid this circular call path.  I think we should have the
cache allocation stuff in the same place where we have relocation, because
it's easier to follow the code then.  So I move arrays alloc/free
functions to slab_common.c too.

The third point isn't obvious.  I'm going to make the list_lru structure
per-memcg to allow targeted kmem reclaim.  That means we will have
per-memcg arrays in list_lrus too.  It turns out that it's much easier to
update these arrays in list_lru.c rather than in memcontrol.c, because all
the stuff we need is defined there.  This patch makes memcg caches arrays
allocation path conform that of the upcoming list_lru.

So let's move these functions to slab_common.c and make them static.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Christoph Lameter <cl@linux.com>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index e0752d204d9e8b8cb9ea658668c7d35f5806a754..4d17242eeff7dedcae380d2b9080c029e8361fbe 100644 (file)
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -440,10 +440,6 @@ void __memcg_kmem_uncharge_pages(struct page *page, int order);
 
 int memcg_cache_id(struct mem_cgroup *memcg);
 
-int memcg_alloc_cache_params(struct mem_cgroup *memcg, struct kmem_cache *s,
-                            struct kmem_cache *root_cache);
-void memcg_free_cache_params(struct kmem_cache *s);
-
 int memcg_update_cache_size(struct kmem_cache *s, int num_groups);
 void memcg_update_array_size(int num_groups);
 
@@ -574,16 +570,6 @@ static inline int memcg_cache_id(struct mem_cgroup *memcg)
        return -1;
 }
 
-static inline int memcg_alloc_cache_params(struct mem_cgroup *memcg,
-               struct kmem_cache *s, struct kmem_cache *root_cache)
-{
-       return 0;
-}
-
-static inline void memcg_free_cache_params(struct kmem_cache *s)
-{
-}
-
 static inline struct kmem_cache *
 memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp)
 {

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 28928ce9b07fbed2529ebdcd708d2aa3345410a4..865e87c014d63e7e78189ca7d132af16030c5547 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2984,43 +2984,6 @@ int memcg_update_cache_size(struct kmem_cache *s, int num_groups)
        return 0;
 }
 
-int memcg_alloc_cache_params(struct mem_cgroup *memcg, struct kmem_cache *s,
-                            struct kmem_cache *root_cache)
-{
-       size_t size;
-
-       if (!memcg_kmem_enabled())
-               return 0;
-
-       if (!memcg) {
-               size = offsetof(struct memcg_cache_params, memcg_caches);
-               size += memcg_limited_groups_array_size * sizeof(void *);
-       } else
-               size = sizeof(struct memcg_cache_params);
-
-       s->memcg_params = kzalloc(size, GFP_KERNEL);
-       if (!s->memcg_params)
-               return -ENOMEM;
-
-       if (memcg) {
-               s->memcg_params->memcg = memcg;
-               s->memcg_params->root_cache = root_cache;
-               css_get(&memcg->css);
-       } else
-               s->memcg_params->is_root_cache = true;
-
-       return 0;
-}
-
-void memcg_free_cache_params(struct kmem_cache *s)
-{
-       if (!s->memcg_params)
-               return;
-       if (!s->memcg_params->is_root_cache)
-               css_put(&s->memcg_params->memcg->css);
-       kfree(s->memcg_params);
-}
-
 static void memcg_register_cache(struct mem_cgroup *memcg,
                                 struct kmem_cache *root_cache)
 {
@@ -3051,6 +3014,7 @@ static void memcg_register_cache(struct mem_cgroup *memcg,
        if (!cachep)
                return;
 
+       css_get(&memcg->css);
        list_add(&cachep->memcg_params->list, &memcg->memcg_slab_caches);
 
        /*
@@ -3084,6 +3048,9 @@ static void memcg_unregister_cache(struct kmem_cache *cachep)
        list_del(&cachep->memcg_params->list);
 
        kmem_cache_destroy(cachep);
+
+       /* drop the reference taken in memcg_register_cache */
+       css_put(&memcg->css);
 }
 
 /*

diff --git a/mm/slab_common.c b/mm/slab_common.c
index f206cb10a544a64ed33606fbe6cae26309db87ad..c2a8661f8b81c89888e6a9b0140b28558a1083f9 100644 (file)
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -116,6 +116,38 @@ static inline int kmem_cache_sanity_check(const char *name, size_t size)
 #endif
 
 #ifdef CONFIG_MEMCG_KMEM
+static int memcg_alloc_cache_params(struct mem_cgroup *memcg,
+               struct kmem_cache *s, struct kmem_cache *root_cache)
+{
+       size_t size;
+
+       if (!memcg_kmem_enabled())
+               return 0;
+
+       if (!memcg) {
+               size = offsetof(struct memcg_cache_params, memcg_caches);
+               size += memcg_limited_groups_array_size * sizeof(void *);
+       } else
+               size = sizeof(struct memcg_cache_params);
+
+       s->memcg_params = kzalloc(size, GFP_KERNEL);
+       if (!s->memcg_params)
+               return -ENOMEM;
+
+       if (memcg) {
+               s->memcg_params->memcg = memcg;
+               s->memcg_params->root_cache = root_cache;
+       } else
+               s->memcg_params->is_root_cache = true;
+
+       return 0;
+}
+
+static void memcg_free_cache_params(struct kmem_cache *s)
+{
+       kfree(s->memcg_params);
+}
+
 int memcg_update_all_caches(int num_memcgs)
 {
        struct kmem_cache *s;
@@ -141,7 +173,17 @@ out:
        mutex_unlock(&slab_mutex);
        return ret;
 }
-#endif
+#else
+static inline int memcg_alloc_cache_params(struct mem_cgroup *memcg,
+               struct kmem_cache *s, struct kmem_cache *root_cache)
+{
+       return 0;
+}
+
+static inline void memcg_free_cache_params(struct kmem_cache *s)
+{
+}
+#endif /* CONFIG_MEMCG_KMEM */
 
 /*
  * Find a mergeable slab cache