[PATCH 4/8] memcg, slab: separate memcg vs root cache creation paths
From: Vladimir Davydov
Date: Sun Feb 02 2014 - 11:36:15 EST
Memcg-awareness turned kmem_cache_create() into a dirty interweaving of
memcg-only and except-for-memcg calls. To clean this up, let's create a
separate function handling memcg caches creation. Although this will
result in the two functions having several hunks of practically the same
code, I guess this is the case when readability fully covers the cost of
code duplication.
Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
---
include/linux/memcontrol.h | 8 +--
include/linux/slab.h | 9 ++-
mm/memcontrol.c | 16 ++----
mm/slab_common.c | 133 ++++++++++++++++++++++++++------------------
4 files changed, 92 insertions(+), 74 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index abd0113b6620..87b8c614798f 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -497,8 +497,8 @@ void __memcg_kmem_commit_charge(struct page *page,
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);
+int memcg_alloc_cache_params(struct kmem_cache *s,
+ struct mem_cgroup *memcg, struct kmem_cache *root_cache);
void memcg_free_cache_params(struct kmem_cache *s);
void memcg_register_cache(struct kmem_cache *s);
void memcg_unregister_cache(struct kmem_cache *s);
@@ -641,8 +641,8 @@ 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)
+static inline int memcg_alloc_cache_params(struct kmem_cache *s,
+ struct mem_cgroup *memcg, struct kmem_cache *root_cache)
{
return 0;
}
diff --git a/include/linux/slab.h b/include/linux/slab.h
index a060142aa5f5..b8a4bad71f57 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -113,11 +113,10 @@ void __init kmem_cache_init(void);
int slab_is_available(void);
struct kmem_cache *kmem_cache_create(const char *, size_t, size_t,
- unsigned long,
- void (*)(void *));
-struct kmem_cache *
-kmem_cache_create_memcg(struct mem_cgroup *, const char *, size_t, size_t,
- unsigned long, void (*)(void *), struct kmem_cache *);
+ unsigned long, void (*)(void *));
+#ifdef CONFIG_MEMCG_KMEM
+int kmem_cache_create_memcg(struct mem_cgroup *, struct kmem_cache *);
+#endif
void 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 3351c5b5486d..d69c427e106b 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3201,8 +3201,8 @@ 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)
+int memcg_alloc_cache_params(struct kmem_cache *s,
+ struct mem_cgroup *memcg, struct kmem_cache *root_cache)
{
size_t size;
@@ -3477,15 +3477,9 @@ struct create_work {
static void memcg_create_cache_work_func(struct work_struct *w)
{
struct create_work *cw = container_of(w, struct create_work, work);
- struct mem_cgroup *memcg = cw->memcg;
- struct kmem_cache *s = cw->cachep;
- struct kmem_cache *new;
-
- new = kmem_cache_create_memcg(memcg, s->name, s->object_size, s->align,
- (s->flags & ~SLAB_PANIC), s->ctor, s);
- if (new)
- new->allocflags |= __GFP_KMEMCG;
- css_put(&memcg->css);
+
+ kmem_cache_create_memcg(cw->memcg, cw->cachep);
+ css_put(&cw->memcg->css);
kfree(cw);
}
diff --git a/mm/slab_common.c b/mm/slab_common.c
index a75834bb966d..ade86bcddab9 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -29,8 +29,7 @@ DEFINE_MUTEX(slab_mutex);
struct kmem_cache *kmem_cache;
#ifdef CONFIG_DEBUG_VM
-static int kmem_cache_sanity_check(struct mem_cgroup *memcg, const char *name,
- size_t size)
+static int kmem_cache_sanity_check(const char *name, size_t size)
{
struct kmem_cache *s = NULL;
@@ -57,13 +56,7 @@ static int kmem_cache_sanity_check(struct mem_cgroup *memcg, const char *name,
}
#if !defined(CONFIG_SLUB) || !defined(CONFIG_SLUB_DEBUG_ON)
- /*
- * For simplicity, we won't check this in the list of memcg
- * caches. We have control over memcg naming, and if there
- * aren't duplicates in the global list, there won't be any
- * duplicates in the memcg lists as well.
- */
- if (!memcg && !strcmp(s->name, name)) {
+ if (!strcmp(s->name, name)) {
pr_err("%s (%s): Cache name already exists.\n",
__func__, name);
dump_stack();
@@ -77,8 +70,7 @@ static int kmem_cache_sanity_check(struct mem_cgroup *memcg, const char *name,
return 0;
}
#else
-static inline int kmem_cache_sanity_check(struct mem_cgroup *memcg,
- const char *name, size_t size)
+static inline int kmem_cache_sanity_check(const char *name, size_t size)
{
return 0;
}
@@ -164,11 +156,9 @@ unsigned long calculate_alignment(unsigned long flags,
* cacheline. This can be beneficial if you're counting cycles as closely
* as davem.
*/
-
struct kmem_cache *
-kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
- size_t align, unsigned long flags, void (*ctor)(void *),
- struct kmem_cache *parent_cache)
+kmem_cache_create(const char *name, size_t size, size_t align,
+ unsigned long flags, void (*ctor)(void *))
{
struct kmem_cache *s = NULL;
int err;
@@ -176,22 +166,10 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
get_online_cpus();
mutex_lock(&slab_mutex);
- err = kmem_cache_sanity_check(memcg, name, size);
+ err = kmem_cache_sanity_check(name, size);
if (err)
goto out_unlock;
- if (memcg) {
- /*
- * Since per-memcg caches are created asynchronously on first
- * allocation (see memcg_kmem_get_cache()), several threads can
- * try to create the same cache, but only one of them may
- * succeed. Therefore if we get here and see the cache has
- * already been created, we silently return NULL.
- */
- if (cache_from_memcg_idx(parent_cache, memcg_cache_id(memcg)))
- goto out_unlock;
- }
-
/*
* Some allocators will constraint the set of valid flags to a subset
* of all flags. We expect them to define CACHE_CREATE_MASK in this
@@ -200,11 +178,9 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
*/
flags &= CACHE_CREATE_MASK;
- if (!memcg) {
- s = __kmem_cache_alias(name, size, align, flags, ctor);
- if (s)
- goto out_unlock;
- }
+ s = __kmem_cache_alias(name, size, align, flags, ctor);
+ if (s)
+ goto out_unlock;
err = -ENOMEM;
s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
@@ -215,15 +191,11 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
s->align = calculate_alignment(flags, align, size);
s->ctor = ctor;
- if (!memcg)
- s->name = kstrdup(name, GFP_KERNEL);
- else
- s->name = kasprintf(GFP_KERNEL, "%s:%d",
- name, memcg_cache_id(memcg));
+ s->name = kstrdup(name, GFP_KERNEL);
if (!s->name)
goto out_free_cache;
- err = memcg_alloc_cache_params(memcg, s, parent_cache);
+ err = memcg_alloc_cache_params(s, NULL, NULL);
if (err)
goto out_free_cache;
@@ -240,16 +212,6 @@ out_unlock:
put_online_cpus();
if (err) {
- /*
- * There is no point in flooding logs with warnings or
- * especially crashing the system if we fail to create a cache
- * for a memcg. In this case we will be accounting the memcg
- * allocation to the root cgroup until we succeed to create its
- * own cache, but it isn't that critical.
- */
- if (!memcg)
- return NULL;
-
if (flags & SLAB_PANIC)
panic("kmem_cache_create: Failed to create slab '%s'. Error %d\n",
name, err);
@@ -268,14 +230,77 @@ out_free_cache:
kmem_cache_free(kmem_cache, s);
goto out_unlock;
}
+EXPORT_SYMBOL(kmem_cache_create);
-struct kmem_cache *
-kmem_cache_create(const char *name, size_t size, size_t align,
- unsigned long flags, void (*ctor)(void *))
+#ifdef CONFIG_MEMCG_KMEM
+/*
+ * kmem_cache_create_memcg - Create a cache for a memory cgroup.
+ * @memcg: The memory cgroup the new cache is for.
+ * @cachep: The parent of the new cache.
+ *
+ * This function creates a kmem cache that will serve allocation requests going
+ * from @memcg to @cachep. The new cache inherits properties from its parent.
+ *
+ * Returns 0 on success, -errno on failure.
+ */
+int kmem_cache_create_memcg(struct mem_cgroup *memcg, struct kmem_cache *cachep)
{
- return kmem_cache_create_memcg(NULL, name, size, align, flags, ctor, NULL);
+ struct kmem_cache *s;
+ int err;
+
+ get_online_cpus();
+ mutex_lock(&slab_mutex);
+
+ /*
+ * Since per-memcg caches are created asynchronously on first
+ * allocation (see memcg_kmem_get_cache()), several threads can try to
+ * create the same cache, but only one of them may succeed.
+ */
+ err = -EEXIST;
+ if (cache_from_memcg_idx(cachep, memcg_cache_id(memcg)))
+ goto out_unlock;
+
+ err = -ENOMEM;
+ s = kmem_cache_zalloc(kmem_cache, GFP_KERNEL);
+ if (!s)
+ goto out_unlock;
+
+ s->object_size = cachep->object_size;
+ s->size = cachep->size;
+ s->align = cachep->align;
+ s->ctor = cachep->ctor;
+
+ s->name = kasprintf(GFP_KERNEL, "%s:%d",
+ cachep->name, memcg_cache_id(memcg));
+ if (!s->name)
+ goto out_free_cache;
+
+ err = memcg_alloc_cache_params(s, memcg, cachep);
+ if (err)
+ goto out_free_cache;
+
+ err = __kmem_cache_create(s, cachep->flags & ~SLAB_PANIC);
+ if (err)
+ goto out_free_cache;
+
+ s->refcount = 1;
+ s->allocflags |= __GFP_KMEMCG;
+ list_add(&s->list, &slab_caches);
+ memcg_register_cache(s);
+
+out_unlock:
+ mutex_unlock(&slab_mutex);
+ put_online_cpus();
+
+ return err;
+
+out_free_cache:
+ memcg_free_cache_params(s);
+ kfree(s->name);
+ kmem_cache_free(kmem_cache, s);
+ goto out_unlock;
}
-EXPORT_SYMBOL(kmem_cache_create);
+#endif /* CONFIG_MEMCG_KMEM */
void kmem_cache_destroy(struct kmem_cache *s)
{
--
1.7.10.4
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