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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>
This commit is contained in:
Vladimir Davydov 2014-01-23 15:52:58 -08:00 committed by Linus Torvalds
parent 363a044f73
commit 1aa1325425
3 changed files with 38 additions and 42 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
include/linux/memcontrol.h
View File

@ -500,8 +500,8 @@ 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);
void memcg_release_cache(struct kmem_cache *cachep);
void memcg_cache_list_add(struct mem_cgroup *memcg, struct kmem_cache *cachep);
void memcg_register_cache(struct kmem_cache *s);
void memcg_unregister_cache(struct kmem_cache *s);
int memcg_update_cache_size(struct kmem_cache *s, int num_groups);
void memcg_update_array_size(int num_groups);
@ -651,12 +651,11 @@ static inline void memcg_free_cache_params(struct kmem_cache *s)
{
}
static inline void memcg_release_cache(struct kmem_cache *cachep)
static inline void memcg_register_cache(struct kmem_cache *s)
{
}
static inline void memcg_cache_list_add(struct mem_cgroup *memcg,
struct kmem_cache *s)
static inline void memcg_unregister_cache(struct kmem_cache *s)
{
}

66
mm/memcontrol.c
View File

@ -3095,16 +3095,6 @@ static void memcg_uncharge_kmem(struct mem_cgroup *memcg, u64 size)
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 @@ void memcg_free_cache_params(struct kmem_cache *s)
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 @@ void memcg_release_cache(struct kmem_cache *s)
mutex_unlock(&memcg->slab_caches_mutex);
css_put(&memcg->css);
out:
memcg_free_cache_params(s);
}
/*
@ -3451,26 +3459,13 @@ static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
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 @@ static void memcg_create_cache_work_func(struct work_struct *w)
cw = container_of(w, struct create_work, work);
memcg_create_kmem_cache(cw->memcg, cw->cachep);
css_put(&cw->memcg->css);
kfree(cw);
}

5
mm/slab_common.c
View File

@ -215,7 +215,7 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
s->refcount = 1;
list_add(&s->list, &slab_caches);
memcg_cache_list_add(memcg, s);
memcg_register_cache(s);
out_unlock:
mutex_unlock(&slab_mutex);
@ -265,7 +265,8 @@ void kmem_cache_destroy(struct kmem_cache *s)
if (s->flags & SLAB_DESTROY_BY_RCU)
rcu_barrier();
memcg_release_cache(s);
memcg_unregister_cache(s);
memcg_free_cache_params(s);
kfree(s->name);
kmem_cache_free(kmem_cache, s);
} else {