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-rw-r--r--mm/memcontrol.c80
1 files changed, 49 insertions, 31 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index b8dc8e4cbf6a..0f1d92163f30 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3321,52 +3321,53 @@ void mem_cgroup_destroy_cache(struct kmem_cache *cachep)
schedule_work(&cachep->memcg_params->destroy);
}
-static char *memcg_cache_name(struct mem_cgroup *memcg, struct kmem_cache *s)
-{
- char *name;
- struct dentry *dentry;
-
- rcu_read_lock();
- dentry = rcu_dereference(memcg->css.cgroup->dentry);
- rcu_read_unlock();
-
- BUG_ON(dentry == NULL);
-
- name = kasprintf(GFP_KERNEL, "%s(%d:%s)", s->name,
- memcg_cache_id(memcg), dentry->d_name.name);
-
- return name;
-}
+/*
+ * This lock protects updaters, not readers. We want readers to be as fast as
+ * they can, and they will either see NULL or a valid cache value. Our model
+ * allow them to see NULL, in which case the root memcg will be selected.
+ *
+ * We need this lock because multiple allocations to the same cache from a non
+ * will span more than one worker. Only one of them can create the cache.
+ */
+static DEFINE_MUTEX(memcg_cache_mutex);
+/*
+ * Called with memcg_cache_mutex held
+ */
static struct kmem_cache *kmem_cache_dup(struct mem_cgroup *memcg,
struct kmem_cache *s)
{
- char *name;
struct kmem_cache *new;
+ static char *tmp_name = NULL;
- name = memcg_cache_name(memcg, s);
- if (!name)
- return NULL;
+ lockdep_assert_held(&memcg_cache_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)
+ return NULL;
+ }
+
+ 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, name, s->object_size, s->align,
+ 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;
- kfree(name);
return new;
}
-/*
- * This lock protects updaters, not readers. We want readers to be as fast as
- * they can, and they will either see NULL or a valid cache value. Our model
- * allow them to see NULL, in which case the root memcg will be selected.
- *
- * We need this lock because multiple allocations to the same cache from a non
- * will span more than one worker. Only one of them can create the cache.
- */
-static DEFINE_MUTEX(memcg_cache_mutex);
static struct kmem_cache *memcg_create_kmem_cache(struct mem_cgroup *memcg,
struct kmem_cache *cachep)
{
@@ -5912,6 +5913,7 @@ static struct cftype mem_cgroup_files[] = {
},
{
.name = "use_hierarchy",
+ .flags = CFTYPE_INSANE,
.write_u64 = mem_cgroup_hierarchy_write,
.read_u64 = mem_cgroup_hierarchy_read,
},
@@ -6907,6 +6909,21 @@ static void mem_cgroup_move_task(struct cgroup *cont,
}
#endif
+/*
+ * Cgroup retains root cgroups across [un]mount cycles making it necessary
+ * to verify sane_behavior flag on each mount attempt.
+ */
+static void mem_cgroup_bind(struct cgroup *root)
+{
+ /*
+ * use_hierarchy is forced with sane_behavior. cgroup core
+ * guarantees that @root doesn't have any children, so turning it
+ * on for the root memcg is enough.
+ */
+ if (cgroup_sane_behavior(root))
+ mem_cgroup_from_cont(root)->use_hierarchy = true;
+}
+
struct cgroup_subsys mem_cgroup_subsys = {
.name = "memory",
.subsys_id = mem_cgroup_subsys_id,
@@ -6917,6 +6934,7 @@ struct cgroup_subsys mem_cgroup_subsys = {
.can_attach = mem_cgroup_can_attach,
.cancel_attach = mem_cgroup_cancel_attach,
.attach = mem_cgroup_move_task,
+ .bind = mem_cgroup_bind,
.base_cftypes = mem_cgroup_files,
.early_init = 0,
.use_id = 1,