memcg, slab: clean up memcg cache initialization/destruction
Currently, we have rather a messy function set relating to per-memcg
kmem cache initialization/destruction.
Per-memcg caches are created in memcg_create_kmem_cache(). This
function calls kmem_cache_create_memcg() to allocate and initialize a
kmem cache and then "registers" the new cache in the
memcg_params::memcg_caches array of the parent cache.
During its work-flow, kmem_cache_create_memcg() executes the following
memcg-related functions:
- memcg_alloc_cache_params(), to initialize memcg_params of the newly
created cache;
- memcg_cache_list_add(), to add the new cache to the memcg_slab_caches
list.
On the other hand, kmem_cache_destroy() called on a cache destruction
only calls memcg_release_cache(), which does all the work: it cleans the
reference to the cache in its parent's memcg_params::memcg_caches,
removes the cache from the memcg_slab_caches list, and frees
memcg_params.
Such an inconsistency between destruction and initialization paths make
the code difficult to read, so let's clean this up a bit.
This patch moves all the code relating to registration of per-memcg
caches (adding to memcg list, setting the pointer to a cache from its
parent) to the newly created memcg_register_cache() and
memcg_unregister_cache() functions making the initialization and
destruction paths look symmetrical.
Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Glauber Costa <glommer@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b8ebe71..739383c 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3095,16 +3095,6 @@
css_put(&memcg->css);
}
-void memcg_cache_list_add(struct mem_cgroup *memcg, struct kmem_cache *cachep)
-{
- if (!memcg)
- return;
-
- mutex_lock(&memcg->slab_caches_mutex);
- list_add(&cachep->memcg_params->list, &memcg->memcg_slab_caches);
- mutex_unlock(&memcg->slab_caches_mutex);
-}
-
/*
* helper for acessing a memcg's index. It will be used as an index in the
* child cache array in kmem_cache, and also to derive its name. This function
@@ -3265,21 +3255,41 @@
kfree(s->memcg_params);
}
-void memcg_release_cache(struct kmem_cache *s)
+void memcg_register_cache(struct kmem_cache *s)
{
struct kmem_cache *root;
struct mem_cgroup *memcg;
int id;
- /*
- * This happens, for instance, when a root cache goes away before we
- * add any memcg.
- */
- if (!s->memcg_params)
+ if (is_root_cache(s))
return;
- if (s->memcg_params->is_root_cache)
- goto out;
+ root = s->memcg_params->root_cache;
+ memcg = s->memcg_params->memcg;
+ id = memcg_cache_id(memcg);
+
+ css_get(&memcg->css);
+
+ mutex_lock(&memcg->slab_caches_mutex);
+ list_add(&s->memcg_params->list, &memcg->memcg_slab_caches);
+ mutex_unlock(&memcg->slab_caches_mutex);
+
+ root->memcg_params->memcg_caches[id] = s;
+ /*
+ * the readers won't lock, make sure everybody sees the updated value,
+ * so they won't put stuff in the queue again for no reason
+ */
+ wmb();
+}
+
+void memcg_unregister_cache(struct kmem_cache *s)
+{
+ struct kmem_cache *root;
+ struct mem_cgroup *memcg;
+ int id;
+
+ if (is_root_cache(s))
+ return;
memcg = s->memcg_params->memcg;
id = memcg_cache_id(memcg);
@@ -3292,8 +3302,6 @@
mutex_unlock(&memcg->slab_caches_mutex);
css_put(&memcg->css);
-out:
- memcg_free_cache_params(s);
}
/*
@@ -3451,26 +3459,13 @@
mutex_lock(&memcg_cache_mutex);
new_cachep = cache_from_memcg_idx(cachep, idx);
- if (new_cachep) {
- css_put(&memcg->css);
+ if (new_cachep)
goto out;
- }
new_cachep = kmem_cache_dup(memcg, cachep);
- if (new_cachep == NULL) {
+ if (new_cachep == NULL)
new_cachep = cachep;
- css_put(&memcg->css);
- goto out;
- }
- atomic_set(&new_cachep->memcg_params->nr_pages , 0);
-
- cachep->memcg_params->memcg_caches[idx] = new_cachep;
- /*
- * the readers won't lock, make sure everybody sees the updated value,
- * so they won't put stuff in the queue again for no reason
- */
- wmb();
out:
mutex_unlock(&memcg_cache_mutex);
return new_cachep;
@@ -3550,6 +3545,7 @@
cw = container_of(w, struct create_work, work);
memcg_create_kmem_cache(cw->memcg, cw->cachep);
+ css_put(&cw->memcg->css);
kfree(cw);
}