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Date: Mon, 3 Nov 2014 23:59:41 +0300
From: Vladimir Davydov <vdavydov@...allels.com>
To: Andrew Morton <akpm@...ux-foundation.org>
CC: Johannes Weiner <hannes@...xchg.org>,
Michal Hocko <mhocko@...e.cz>,
Christoph Lameter <cl@...ux.com>,
Pekka Enberg <penberg@...nel.org>,
David Rientjes <rientjes@...gle.com>,
Joonsoo Kim <iamjoonsoo.kim@....com>, <linux-mm@...ck.org>,
<linux-kernel@...r.kernel.org>
Subject: [PATCH -mm 3/8] memcg: decouple per memcg kmem cache from the owner memcg
Basically, we substitute the reference to the owner memory cgroup in
memcg_cache_params with the index in the memcg_caches array. This
decouples kmem cache from the memcg it was created for and will allow to
reuse it for another cgroup after css offline.
Signed-off-by: Vladimir Davydov <vdavydov@...allels.com>
---
include/linux/slab.h | 7 +++----
mm/memcontrol.c | 18 +++++-------------
mm/slab_common.c | 12 +++++-------
3 files changed, 13 insertions(+), 24 deletions(-)
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 390341d30b2d..293c04df7953 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -117,8 +117,7 @@ struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
void (*)(void *));
#ifdef CONFIG_MEMCG_KMEM
struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *,
- struct kmem_cache *,
- const char *);
+ struct kmem_cache *);
#endif
void kmem_cache_destroy(struct kmem_cache *);
int kmem_cache_shrink(struct kmem_cache *);
@@ -490,7 +489,7 @@ static __always_inline void *kmalloc_node(size_t size, gfp_t flags, int node)
*
* Child caches will hold extra metadata needed for its operation. Fields are:
*
- * @memcg: pointer to the memcg this cache belongs to
+ * @id: the index in the root_cache's memcg_caches array.
* @root_cache: pointer to the global, root cache, this cache was derived from
*/
struct memcg_cache_params {
@@ -501,7 +500,7 @@ struct memcg_cache_params {
struct kmem_cache *memcg_caches[0];
};
struct {
- struct mem_cgroup *memcg;
+ int id;
struct kmem_cache *root_cache;
};
};
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 8c60d7a30f4f..78d12076b01d 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2603,8 +2603,6 @@ void memcg_update_array_size(int num)
static void memcg_register_cache(struct mem_cgroup *memcg,
struct kmem_cache *root_cache)
{
- static char memcg_name_buf[NAME_MAX + 1]; /* protected by
- memcg_slab_mutex */
struct kmem_cache *cachep;
int id;
@@ -2620,8 +2618,7 @@ static void memcg_register_cache(struct mem_cgroup *memcg,
if (cache_from_memcg_idx(root_cache, id))
return;
- cgroup_name(memcg->css.cgroup, memcg_name_buf, NAME_MAX + 1);
- cachep = memcg_create_kmem_cache(memcg, root_cache, memcg_name_buf);
+ cachep = memcg_create_kmem_cache(memcg, root_cache);
/*
* If we could not create a memcg cache, do not complain, because
* that's not critical at all as we can always proceed with the root
@@ -2630,8 +2627,6 @@ static void memcg_register_cache(struct mem_cgroup *memcg,
if (!cachep)
return;
- css_get(&memcg->css);
-
/*
* Since readers won't lock (see cache_from_memcg_idx()), we need a
* barrier here to ensure nobody will see the kmem_cache partially
@@ -2646,7 +2641,6 @@ static void memcg_register_cache(struct mem_cgroup *memcg,
static void memcg_unregister_cache(struct kmem_cache *cachep)
{
struct kmem_cache *root_cache;
- struct mem_cgroup *memcg;
int id;
lockdep_assert_held(&memcg_slab_mutex);
@@ -2654,16 +2648,12 @@ static void memcg_unregister_cache(struct kmem_cache *cachep)
BUG_ON(is_root_cache(cachep));
root_cache = cachep->memcg_params->root_cache;
- memcg = cachep->memcg_params->memcg;
- id = memcg_cache_id(memcg);
+ id = cachep->memcg_params->id;
BUG_ON(root_cache->memcg_params->memcg_caches[id] != cachep);
root_cache->memcg_params->memcg_caches[id] = NULL;
kmem_cache_destroy(cachep);
-
- /* drop the reference taken in memcg_register_cache */
- css_put(&memcg->css);
}
/*
@@ -4198,7 +4188,6 @@ static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
{
int ret;
- memcg->kmemcg_id = -1;
ret = memcg_propagate_kmem(memcg);
if (ret)
return ret;
@@ -4743,6 +4732,9 @@ mem_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
vmpressure_init(&memcg->vmpressure);
INIT_LIST_HEAD(&memcg->event_list);
spin_lock_init(&memcg->event_list_lock);
+#ifdef CONFIG_MEMCG_KMEM
+ memcg->kmemcg_id = -1;
+#endif
return &memcg->css;
diff --git a/mm/slab_common.c b/mm/slab_common.c
index d5e9e050a3ec..974d77db1b39 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -125,7 +125,7 @@ static int memcg_alloc_cache_params(struct mem_cgroup *memcg,
return -ENOMEM;
if (memcg) {
- s->memcg_params->memcg = memcg;
+ s->memcg_params->id = memcg_cache_id(memcg);
s->memcg_params->root_cache = root_cache;
} else
s->memcg_params->is_root_cache = true;
@@ -426,15 +426,13 @@ EXPORT_SYMBOL(kmem_cache_create);
* memcg_create_kmem_cache - Create a cache for a memory cgroup.
* @memcg: The memory cgroup the new cache is for.
* @root_cache: The parent of the new cache.
- * @memcg_name: The name of the memory cgroup (used for naming the new cache).
*
* This function attempts to create a kmem cache that will serve allocation
* requests going from @memcg to @root_cache. The new cache inherits properties
* from its parent.
*/
struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
- struct kmem_cache *root_cache,
- const char *memcg_name)
+ struct kmem_cache *root_cache)
{
struct kmem_cache *s = NULL;
char *cache_name;
@@ -444,8 +442,8 @@ struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
mutex_lock(&slab_mutex);
- cache_name = kasprintf(GFP_KERNEL, "%s(%d:%s)", root_cache->name,
- memcg_cache_id(memcg), memcg_name);
+ cache_name = kasprintf(GFP_KERNEL, "%s(%d)", root_cache->name,
+ memcg_cache_id(memcg));
if (!cache_name)
goto out_unlock;
@@ -912,7 +910,7 @@ int memcg_slab_show(struct seq_file *m, void *p)
if (p == slab_caches.next)
print_slabinfo_header(m);
- if (!is_root_cache(s) && s->memcg_params->memcg == memcg)
+ if (!is_root_cache(s) && s->memcg_params->id == memcg_cache_id(memcg))
cache_show(s, m);
return 0;
}
--
1.7.10.4
--
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