The way memcg_create_kmem_cache() creates the name for a memcg cache
looks rather strange: it first formats the name in the static buffer
tmp_name protected by a mutex, then passes the pointer to the buffer to
kmem_cache_create_memcg(), which finally duplicates it to the cache
name.
Let's clean this up by moving memcg cache name creation to a separate
function to be called by kmem_cache_create_memcg(), and estimating the
length of the name string before copying anything to it so that we won't
need a temporary buffer.
Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
---
include/linux/memcontrol.h | 9 +++++
mm/memcontrol.c | 94 ++++++++++++++++++++++----------------------
mm/slab_common.c | 5 ++-
3 files changed, 59 insertions(+), 49 deletions(-)
diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index abd0113b6620..84e4801fc36c 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -497,6 +497,9 @@ 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);
+
+char *memcg_create_cache_name(struct mem_cgroup *memcg,
+ struct kmem_cache *root_cache);
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);
@@ -641,6 +644,12 @@ static inline int memcg_cache_id(struct mem_cgroup *memcg)
return -1;
}
+static inline char *memcg_create_cache_name(struct mem_cgroup *memcg,
+ struct kmem_cache *root_cache)
+{
+ return NULL;
+}
+
static inline int memcg_alloc_cache_params(struct mem_cgroup *memcg,
struct kmem_cache *s, struct kmem_cache *root_cache)
{
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 53385cd4e6f0..9e321650efb2 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3193,6 +3193,37 @@ int memcg_update_cache_size(struct kmem_cache *s, int num_groups)
return 0;
}
+static int memcg_print_cache_name(char *buf, size_t size,
+ struct mem_cgroup *memcg, struct kmem_cache *root_cache)
+{
+ int ret;
+
+ rcu_read_lock();
+ ret = snprintf(buf, size, "%s(%d:%s)", root_cache->name,
+ memcg_cache_id(memcg), cgroup_name(memcg->css.cgroup));
+ rcu_read_unlock();
+ return ret;
+}
+
+char *memcg_create_cache_name(struct mem_cgroup *memcg,
+ struct kmem_cache *root_cache)
+{
+ int len;
+ char *name;
+
+ /*
+ * We cannot use kasprintf() here, because cgroup_name() must be called
+ * under RCU protection.
+ */
+ len = memcg_print_cache_name(NULL, 0, memcg, root_cache);
+
+ name = kmalloc(len + 1, GFP_KERNEL);
+ if (name)
+ memcg_print_cache_name(name, len + 1, memcg, root_cache);
+
+ return name;
+}
+
int memcg_alloc_cache_params(struct mem_cgroup *memcg, struct kmem_cache *s,
struct kmem_cache *root_cache)
{
@@ -3397,44 +3428,6 @@ void mem_cgroup_destroy_cache(struct kmem_cache *cachep)
schedule_work(&cachep->memcg_params->destroy);
}
-static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
- struct kmem_cache *s)
-{
- struct kmem_cache *new = NULL;
- static char *tmp_name = NULL;
- static DEFINE_MUTEX(mutex); /* protects tmp_name */
-
- BUG_ON(!memcg_can_account_kmem(memcg));
-
- mutex_lock(&mutex);
- /*
- * kmem_cache_create_memcg duplicates the given name and
- * cgroup_name for this name requires RCU context.
- * This static temporary buffer is used to prevent from
- * pointless shortliving allocation.
- */
- if (!tmp_name) {
- tmp_name = kmalloc(PATH_MAX, GFP_KERNEL);
- if (!tmp_name)
- goto out;
- }
-
- rcu_read_lock();
- snprintf(tmp_name, PATH_MAX, "%s(%d:%s)", s->name,
- memcg_cache_id(memcg), cgroup_name(memcg->css.cgroup));
- rcu_read_unlock();
-
- new = kmem_cache_create_memcg(memcg, tmp_name, s->object_size, s->align,
- (s->flags & ~SLAB_PANIC), s->ctor, s);
- if (new)
- new->allocflags |= __GFP_KMEMCG;
- else
- new = s;
-out:
- mutex_unlock(&mutex);
- return new;
-}
-
void kmem_cache_destroy_memcg_children(struct kmem_cache *s)
{
struct kmem_cache *c;
@@ -3481,12 +3474,6 @@ void kmem_cache_destroy_memcg_children(struct kmem_cache *s)
mutex_unlock(&activate_kmem_mutex);
}
-struct create_work {
- struct mem_cgroup *memcg;
- struct kmem_cache *cachep;
- struct work_struct work;
-};
-
static void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)
{
struct kmem_cache *cachep;
@@ -3504,13 +3491,24 @@ static void mem_cgroup_destroy_all_caches(struct mem_cgroup *memcg)
mutex_unlock(&memcg->slab_caches_mutex);
}
+struct create_work {
+ struct mem_cgroup *memcg;
+ struct kmem_cache *cachep;
+ struct work_struct work;
+};
+
static void memcg_create_cache_work_func(struct work_struct *w)
{
- struct create_work *cw;
+ 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;
- cw = container_of(w, struct create_work, work);
- memcg_create_kmem_cache(cw->memcg, cw->cachep);
- css_put(&cw->memcg->css);
+ 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);
kfree(cw);
}
diff --git a/mm/slab_common.c b/mm/slab_common.c
index e77b51eb7347..11857abf7057 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -215,7 +215,10 @@ kmem_cache_create_memcg(struct mem_cgroup *memcg, const char *name, size_t size,
s->align = calculate_alignment(flags, align, size);
s->ctor = ctor;
- s->name = kstrdup(name, GFP_KERNEL);
+ if (memcg)
+ s->name = memcg_create_cache_name(memcg, parent_cache);
+ else
+ s->name = kstrdup(name, GFP_KERNEL);
if (!s->name)
goto out_free_cache;
--
1.7.10.4
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