memcg/sl[au]b: track all the memcg children of a kmem_cache
[~shefty/rdma-dev.git] / mm / memcontrol.c
index 270a36789859a43059cb72e14701b4680575976c..4b68ec2c8df6930bc9b2aaf13d276a9aa1131043 100644 (file)
@@ -2772,6 +2772,8 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *memcg,
        memcg_check_events(memcg, page);
 }
 
+static DEFINE_MUTEX(set_limit_mutex);
+
 #ifdef CONFIG_MEMCG_KMEM
 static inline bool memcg_can_account_kmem(struct mem_cgroup *memcg)
 {
@@ -3176,6 +3178,51 @@ out:
        return new_cachep;
 }
 
+void kmem_cache_destroy_memcg_children(struct kmem_cache *s)
+{
+       struct kmem_cache *c;
+       int i;
+
+       if (!s->memcg_params)
+               return;
+       if (!s->memcg_params->is_root_cache)
+               return;
+
+       /*
+        * If the cache is being destroyed, we trust that there is no one else
+        * requesting objects from it. Even if there are, the sanity checks in
+        * kmem_cache_destroy should caught this ill-case.
+        *
+        * Still, we don't want anyone else freeing memcg_caches under our
+        * noses, which can happen if a new memcg comes to life. As usual,
+        * we'll take the set_limit_mutex to protect ourselves against this.
+        */
+       mutex_lock(&set_limit_mutex);
+       for (i = 0; i < memcg_limited_groups_array_size; i++) {
+               c = s->memcg_params->memcg_caches[i];
+               if (!c)
+                       continue;
+
+               /*
+                * We will now manually delete the caches, so to avoid races
+                * we need to cancel all pending destruction workers and
+                * proceed with destruction ourselves.
+                *
+                * kmem_cache_destroy() will call kmem_cache_shrink internally,
+                * and that could spawn the workers again: it is likely that
+                * the cache still have active pages until this very moment.
+                * This would lead us back to mem_cgroup_destroy_cache.
+                *
+                * But that will not execute at all if the "dead" flag is not
+                * set, so flip it down to guarantee we are in control.
+                */
+               c->memcg_params->dead = false;
+               cancel_delayed_work_sync(&c->memcg_params->destroy);
+               kmem_cache_destroy(c);
+       }
+       mutex_unlock(&set_limit_mutex);
+}
+
 struct create_work {
        struct mem_cgroup *memcg;
        struct kmem_cache *cachep;
@@ -4284,8 +4331,6 @@ void mem_cgroup_print_bad_page(struct page *page)
 }
 #endif
 
-static DEFINE_MUTEX(set_limit_mutex);
-
 static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
                                unsigned long long val)
 {