[Devel] [PATCH -mm v2 4/6] memcg: get rid of memcg_{alloc, free}_cache_params
Vladimir Davydov
vdavydov at parallels.com
Sun Apr 27 02:04:06 PDT 2014
The only reason why we have special functions for initializing
memcg_cache_params, memcg_{alloc,free}_cache_params defined at
memcontrol.c, is that we can't do css_{get,put} in slab_common.c.
However, we can move css_{get,put} to memcg_kmem_{create,destroy}_cache,
becuase they are only called when creating/destroying per memcg caches.
Then the rest of memcg_{alloc,free}_cache_params can be inlined in
slab_common.c making the code clearer.
Note, to properly bail out in memcg_kmem_destroy_cache, I need to know
if the cache was actually destroyed (it won't if it has leaked objects).
That's why I add the return value to kmem_cache_destroy.
Signed-off-by: Vladimir Davydov <vdavydov at parallels.com>
---
include/linux/memcontrol.h | 14 ------------
include/linux/slab.h | 2 +-
mm/memcontrol.c | 48 +++++++++++++++--------------------------
mm/slab_common.c | 51 ++++++++++++++++++++++++++++++++------------
4 files changed, 55 insertions(+), 60 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index 6e59393e03f9..3aee79fc7876 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -492,10 +492,6 @@ 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);
-
struct kmem_cache *
__memcg_kmem_get_cache(struct kmem_cache *cachep, gfp_t gfp);
@@ -623,16 +619,6 @@ 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/include/linux/slab.h b/include/linux/slab.h
index c437be67917b..d041539b2bfb 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -122,7 +122,7 @@ struct kmem_cache *kmem_cache_create_memcg(struct mem_cgroup *,
int kmem_cache_init_memcg_array(struct kmem_cache *, int);
int kmem_cache_memcg_arrays_grow(int);
#endif
-void kmem_cache_destroy(struct kmem_cache *);
+int kmem_cache_destroy(struct kmem_cache *);
int kmem_cache_shrink(struct kmem_cache *);
void kmem_cache_free(struct kmem_cache *, void *);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 714d7bd7f140..415c81c2710a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3075,32 +3075,6 @@ out_rmid:
return err;
}
-int memcg_alloc_cache_params(struct mem_cgroup *memcg, struct kmem_cache *s,
- struct kmem_cache *root_cache)
-{
- if (!memcg)
- return 0;
-
- s->memcg_params = kzalloc(sizeof(*s->memcg_params), GFP_KERNEL);
- if (!s->memcg_params)
- return -ENOMEM;
-
- s->memcg_params->memcg = memcg;
- s->memcg_params->root_cache = root_cache;
- css_get(&memcg->css);
-
- 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);
-}
-
/*
* Prepares the memcg_caches array of the given kmem cache for disposing
* memcgs' copies.
@@ -3154,6 +3128,7 @@ static void memcg_kmem_create_cache(struct mem_cgroup *memcg,
if (!cachep)
return;
+ css_get(&memcg->css);
list_add(&cachep->memcg_params->list, &memcg->memcg_slab_caches);
/*
@@ -3167,7 +3142,7 @@ static void memcg_kmem_create_cache(struct mem_cgroup *memcg,
root_cache->memcg_params->memcg_caches[id] = cachep;
}
-static void memcg_kmem_destroy_cache(struct kmem_cache *cachep)
+static int memcg_kmem_destroy_cache(struct kmem_cache *cachep)
{
struct kmem_cache *root_cache;
struct mem_cgroup *memcg;
@@ -3181,12 +3156,25 @@ static void memcg_kmem_destroy_cache(struct kmem_cache *cachep)
memcg = cachep->memcg_params->memcg;
id = memcg_cache_id(memcg);
+ /*
+ * Since memcg_caches arrays can be accessed using only slab_mutex for
+ * protection (e.g. by slabinfo readers), we must clear the cache's
+ * entry before trying to destroy it.
+ */
BUG_ON(root_cache->memcg_params->memcg_caches[id] != cachep);
root_cache->memcg_params->memcg_caches[id] = NULL;
list_del(&cachep->memcg_params->list);
- kmem_cache_destroy(cachep);
+ if (kmem_cache_destroy(cachep) != 0) {
+ root_cache->memcg_params->memcg_caches[id] = cachep;
+ list_add(&cachep->memcg_params->list,
+ &memcg->memcg_slab_caches);
+ return -EBUSY;
+ }
+
+ css_put(&memcg->css);
+ return 0;
}
/*
@@ -3231,9 +3219,7 @@ int __kmem_cache_destroy_memcg_children(struct kmem_cache *s)
if (!c)
continue;
- memcg_kmem_destroy_cache(c);
-
- if (cache_from_memcg_idx(s, i))
+ if (memcg_kmem_destroy_cache(c) != 0)
failed++;
}
mutex_unlock(&memcg_slab_mutex);
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 801999247619..055506ba6d37 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -177,7 +177,7 @@ unsigned long calculate_alignment(unsigned long flags,
static struct kmem_cache *
do_kmem_cache_create(char *name, size_t object_size, size_t size, size_t align,
unsigned long flags, void (*ctor)(void *),
- struct mem_cgroup *memcg, struct kmem_cache *root_cache)
+ struct memcg_cache_params *memcg_params)
{
struct kmem_cache *s;
int err;
@@ -192,10 +192,9 @@ do_kmem_cache_create(char *name, size_t object_size, size_t size, size_t align,
s->size = size;
s->align = align;
s->ctor = ctor;
-
- err = memcg_alloc_cache_params(memcg, s, root_cache);
- if (err)
- goto out_free_cache;
+#ifdef CONFIG_MEMCG_KMEM
+ s->memcg_params = memcg_params;
+#endif
err = __kmem_cache_create(s, flags);
if (err)
@@ -209,7 +208,6 @@ out:
return s;
out_free_cache:
- memcg_free_cache_params(s);
kfree(s);
goto out;
}
@@ -275,7 +273,7 @@ kmem_cache_create(const char *name, size_t size, size_t align,
s = do_kmem_cache_create(cache_name, size, size,
calculate_alignment(flags, align, size),
- flags, ctor, NULL, NULL);
+ flags, ctor, NULL);
if (IS_ERR(s)) {
err = PTR_ERR(s);
kfree(cache_name);
@@ -318,13 +316,21 @@ struct kmem_cache *kmem_cache_create_memcg(struct mem_cgroup *memcg,
const char *memcg_name)
{
struct kmem_cache *s = NULL;
- char *cache_name;
+ char *cache_name = NULL;
+ struct memcg_cache_params *memcg_params = NULL;
get_online_cpus();
get_online_mems();
mutex_lock(&slab_mutex);
+ memcg_params = kzalloc(sizeof(*memcg_params), GFP_KERNEL);
+ if (!memcg_params)
+ goto out_unlock;
+
+ memcg_params->memcg = memcg;
+ memcg_params->root_cache = root_cache;
+
cache_name = kasprintf(GFP_KERNEL, "%s(%d:%s)", root_cache->name,
memcg_cache_id(memcg), memcg_name);
if (!cache_name)
@@ -333,11 +339,9 @@ struct kmem_cache *kmem_cache_create_memcg(struct mem_cgroup *memcg,
s = do_kmem_cache_create(cache_name, root_cache->object_size,
root_cache->size, root_cache->align,
root_cache->flags, root_cache->ctor,
- memcg, root_cache);
- if (IS_ERR(s)) {
- kfree(cache_name);
+ memcg_params);
+ if (IS_ERR(s))
s = NULL;
- }
out_unlock:
mutex_unlock(&slab_mutex);
@@ -345,6 +349,10 @@ out_unlock:
put_online_mems();
put_online_cpus();
+ if (!s) {
+ kfree(memcg_params);
+ kfree(cache_name);
+ }
return s;
}
@@ -369,8 +377,17 @@ static int kmem_cache_destroy_memcg_children(struct kmem_cache *s)
}
#endif /* CONFIG_MEMCG_KMEM */
-void kmem_cache_destroy(struct kmem_cache *s)
+/*
+ * kmem_cache_destroy - Destroy a cache.
+ * @s: The cache to destroy.
+ *
+ * Returns 0 on success. If the cache still has objects, -EBUSY is returned and
+ * a warning is printed to the log.
+ */
+int kmem_cache_destroy(struct kmem_cache *s)
{
+ int ret = 0;
+
get_online_cpus();
get_online_mems();
@@ -380,6 +397,7 @@ void kmem_cache_destroy(struct kmem_cache *s)
if (s->refcount)
goto out_unlock;
+ ret = -EBUSY;
if (kmem_cache_destroy_memcg_children(s) != 0)
goto out_unlock;
@@ -396,9 +414,12 @@ void kmem_cache_destroy(struct kmem_cache *s)
if (s->flags & SLAB_DESTROY_BY_RCU)
rcu_barrier();
- memcg_free_cache_params(s);
+#ifdef CONFIG_MEMCG_KMEM
+ kfree(s->memcg_params);
+#endif
kfree(s->name);
kmem_cache_free(kmem_cache, s);
+ ret = 0;
goto out;
out_unlock:
@@ -406,6 +427,8 @@ out_unlock:
out:
put_online_mems();
put_online_cpus();
+
+ return ret;
}
EXPORT_SYMBOL(kmem_cache_destroy);
--
1.7.10.4
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