1 files changed, 374 insertions, 76 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index fb7440dd7ecc..fe4f123f1170 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -49,6 +49,7 @@
 #include <linux/fs.h>
 #include <linux/seq_file.h>
 #include <linux/vmalloc.h>
+#include <linux/vmpressure.h>
 #include <linux/mm_inline.h>
 #include <linux/page_cgroup.h>
 #include <linux/cpu.h>
@@ -152,8 +153,13 @@ struct mem_cgroup_stat_cpu {
 };
 
 struct mem_cgroup_reclaim_iter {
-	/* css_id of the last scanned hierarchy member */
-	int position;
+	/*
+	 * last scanned hierarchy member. Valid only if last_dead_count
+	 * matches memcg->dead_count of the hierarchy root group.
+	 */
+	struct mem_cgroup *last_visited;
+	unsigned long last_dead_count;
+
 	/* scan generation, increased every round-trip */
 	unsigned int generation;
 };
@@ -256,6 +262,9 @@ struct mem_cgroup {
 	 */
 	struct res_counter res;
 
+	/* vmpressure notifications */
+	struct vmpressure vmpressure;
+
 	union {
 		/*
 		 * the counter to account for mem+swap usage.
@@ -310,14 +319,31 @@ struct mem_cgroup {
 	/* thresholds for mem+swap usage. RCU-protected */
 	struct mem_cgroup_thresholds memsw_thresholds;
 
-	/* For oom notifier event fd */
-	struct list_head oom_notify;
+	union {
+		/* For oom notifier event fd */
+		struct list_head oom_notify;
+		/*
+		 * we can only trigger an oom event if the memcg is alive.
+		 * so we will reuse this field to hook the memcg in the list
+		 * of dead memcgs.
+		 */
+		struct list_head dead;
+	};
 
-	/*
-	 * Should we move charges of a task when a task is moved into this
-	 * mem_cgroup ? And what type of charges should we move ?
-	 */
-	unsigned long 	move_charge_at_immigrate;
+	union {
+		/*
+		 * Should we move charges of a task when a task is moved into
+		 * this mem_cgroup ? And what type of charges should we move ?
+		 */
+		unsigned long move_charge_at_immigrate;
+
+		/*
+		 * We are no longer concerned about moving charges after memcg
+		 * is dead. So we will fill this up with its name, to aid
+		 * debugging.
+		 */
+		char *memcg_name;
+	};
 	/*
 	 * set > 0 if pages under this cgroup are moving to other cgroup.
 	 */
@@ -335,6 +361,7 @@ struct mem_cgroup {
 	struct mem_cgroup_stat_cpu nocpu_base;
 	spinlock_t pcp_counter_lock;
 
+	atomic_t	dead_count;
 #if defined(CONFIG_MEMCG_KMEM) && defined(CONFIG_INET)
 	struct tcp_memcontrol tcp_mem;
 #endif
@@ -353,6 +380,7 @@ struct mem_cgroup {
 	atomic_t	numainfo_events;
 	atomic_t	numainfo_updating;
 #endif
+
 	/*
 	 * Per cgroup active and inactive list, similar to the
 	 * per zone LRU lists.
@@ -369,6 +397,55 @@ static size_t memcg_size(void)
 		nr_node_ids * sizeof(struct mem_cgroup_per_node);
 }
 
+#ifdef CONFIG_MEMCG_DEBUG_ASYNC_DESTROY
+static LIST_HEAD(dangling_memcgs);
+static DEFINE_MUTEX(dangling_memcgs_mutex);
+
+static inline void memcg_dangling_free(struct mem_cgroup *memcg)
+{
+	mutex_lock(&dangling_memcgs_mutex);
+	list_del(&memcg->dead);
+	mutex_unlock(&dangling_memcgs_mutex);
+	free_pages((unsigned long)memcg->memcg_name, 0);
+}
+
+static inline void memcg_dangling_add(struct mem_cgroup *memcg)
+{
+	/*
+	 * cgroup.c will do page-sized allocations most of the time,
+	 * so we'll just follow the pattern. Also, __get_free_pages
+	 * is a better interface than kmalloc for us here, because
+	 * we'd like this memory to be always billed to the root cgroup,
+	 * not to the process removing the memcg. While kmalloc would
+	 * require us to wrap it into memcg_stop/resume_kmem_account,
+	 * with __get_free_pages we just don't pass the memcg flag.
+	 */
+	memcg->memcg_name = (char *)__get_free_pages(GFP_KERNEL, 0);
+
+	/*
+	 * we will, in general, just ignore failures. No need to go crazy,
+	 * being this just a debugging interface. It is nice to copy a memcg
+	 * name over, but if we (unlikely) can't, just the address will do
+	 */
+	if (!memcg->memcg_name)
+		goto add_list;
+
+	if (cgroup_path(memcg->css.cgroup, memcg->memcg_name, PAGE_SIZE) < 0) {
+		free_pages((unsigned long)memcg->memcg_name, 0);
+		memcg->memcg_name = NULL;
+	}
+
+add_list:
+	INIT_LIST_HEAD(&memcg->dead);
+	mutex_lock(&dangling_memcgs_mutex);
+	list_add(&memcg->dead, &dangling_memcgs);
+	mutex_unlock(&dangling_memcgs_mutex);
+}
+#else
+static inline void memcg_dangling_free(struct mem_cgroup *memcg) {}
+static inline void memcg_dangling_add(struct mem_cgroup *memcg) {}
+#endif
+
 /* internal only representation about the status of kmem accounting. */
 enum {
 	KMEM_ACCOUNTED_ACTIVE = 0, /* accounted by this cgroup itself */
@@ -504,6 +581,24 @@ struct mem_cgroup *mem_cgroup_from_css(struct cgroup_subsys_state *s)
 	return container_of(s, struct mem_cgroup, css);
 }
 
+/* Some nice accessors for the vmpressure. */
+struct vmpressure *memcg_to_vmpressure(struct mem_cgroup *memcg)
+{
+	if (!memcg)
+		memcg = root_mem_cgroup;
+	return &memcg->vmpressure;
+}
+
+struct cgroup_subsys_state *vmpressure_to_css(struct vmpressure *vmpr)
+{
+	return &container_of(vmpr, struct mem_cgroup, vmpressure)->css;
+}
+
+struct vmpressure *css_to_vmpressure(struct cgroup_subsys_state *css)
+{
+	return &mem_cgroup_from_css(css)->vmpressure;
+}
+
 static inline bool mem_cgroup_is_root(struct mem_cgroup *memcg)
 {
 	return (memcg == root_mem_cgroup);
@@ -1067,6 +1162,51 @@ struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
 	return memcg;
 }
 
+/*
+ * Returns a next (in a pre-order walk) alive memcg (with elevated css
+ * ref. count) or NULL if the whole root's subtree has been visited.
+ *
+ * helper function to be used by mem_cgroup_iter
+ */
+static struct mem_cgroup *__mem_cgroup_iter_next(struct mem_cgroup *root,
+		struct mem_cgroup *last_visited)
+{
+	struct cgroup *prev_cgroup, *next_cgroup;
+
+	/*
+	 * Root is not visited by cgroup iterators so it needs an
+	 * explicit visit.
+	 */
+	if (!last_visited)
+		return root;
+
+	prev_cgroup = (last_visited == root) ? NULL
+		: last_visited->css.cgroup;
+skip_node:
+	next_cgroup = cgroup_next_descendant_pre(
+			prev_cgroup, root->css.cgroup);
+
+	/*
+	 * Even if we found a group we have to make sure it is
+	 * alive. css && !memcg means that the groups should be
+	 * skipped and we should continue the tree walk.
+	 * last_visited css is safe to use because it is
+	 * protected by css_get and the tree walk is rcu safe.
+	 */
+	if (next_cgroup) {
+		struct mem_cgroup *mem = mem_cgroup_from_cont(
+				next_cgroup);
+		if (css_tryget(&mem->css))
+			return mem;
+		else {
+			prev_cgroup = next_cgroup;
+			goto skip_node;
+		}
+	}
+
+	return NULL;
+}
+
 /**
  * mem_cgroup_iter - iterate over memory cgroup hierarchy
  * @root: hierarchy root
@@ -1089,7 +1229,8 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
 				   struct mem_cgroup_reclaim_cookie *reclaim)
 {
 	struct mem_cgroup *memcg = NULL;
-	int id = 0;
+	struct mem_cgroup *last_visited = NULL;
+	unsigned long uninitialized_var(dead_count);
 
 	if (mem_cgroup_disabled())
 		return NULL;
@@ -1098,20 +1239,17 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
 		root = root_mem_cgroup;
 
 	if (prev && !reclaim)
-		id = css_id(&prev->css);
-
-	if (prev && prev != root)
-		css_put(&prev->css);
+		last_visited = prev;
 
 	if (!root->use_hierarchy && root != root_mem_cgroup) {
 		if (prev)
-			return NULL;
+			goto out_css_put;
 		return root;
 	}
 
+	rcu_read_lock();
 	while (!memcg) {
 		struct mem_cgroup_reclaim_iter *uninitialized_var(iter);
-		struct cgroup_subsys_state *css;
 
 		if (reclaim) {
 			int nid = zone_to_nid(reclaim->zone);
@@ -1120,31 +1258,60 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
 
 			mz = mem_cgroup_zoneinfo(root, nid, zid);
 			iter = &mz->reclaim_iter[reclaim->priority];
-			if (prev && reclaim->generation != iter->generation)
-				return NULL;
-			id = iter->position;
+			last_visited = iter->last_visited;
+			if (prev && reclaim->generation != iter->generation) {
+				iter->last_visited = NULL;
+				goto out_unlock;
+			}
+
+			/*
+			 * If the dead_count mismatches, a destruction
+			 * has happened or is happening concurrently.
+			 * If the dead_count matches, a destruction
+			 * might still happen concurrently, but since
+			 * we checked under RCU, that destruction
+			 * won't free the object until we release the
+			 * RCU reader lock.  Thus, the dead_count
+			 * check verifies the pointer is still valid,
+			 * css_tryget() verifies the cgroup pointed to
+			 * is alive.
+			 */
+			dead_count = atomic_read(&root->dead_count);
+			smp_rmb();
+			last_visited = iter->last_visited;
+			if (last_visited) {
+				if ((dead_count != iter->last_dead_count) ||
+					!css_tryget(&last_visited->css)) {
+					last_visited = NULL;
+				}
+			}
 		}
 
-		rcu_read_lock();
-		css = css_get_next(&mem_cgroup_subsys, id + 1, &root->css, &id);
-		if (css) {
-			if (css == &root->css || css_tryget(css))
-				memcg = mem_cgroup_from_css(css);
-		} else
-			id = 0;
-		rcu_read_unlock();
+		memcg = __mem_cgroup_iter_next(root, last_visited);
 
 		if (reclaim) {
-			iter->position = id;
-			if (!css)
+			if (last_visited)
+				css_put(&last_visited->css);
+
+			iter->last_visited = memcg;
+			smp_wmb();
+			iter->last_dead_count = dead_count;
+
+			if (!memcg)
 				iter->generation++;
 			else if (!prev && memcg)
 				reclaim->generation = iter->generation;
 		}
 
-		if (prev && !css)
-			return NULL;
+		if (prev && !memcg)
+			goto out_unlock;
 	}
+out_unlock:
+	rcu_read_unlock();
+out_css_put:
+	if (prev && prev != root)
+		css_put(&prev->css);
+
 	return memcg;
 }
 
@@ -1686,11 +1853,11 @@ static void mem_cgroup_out_of_memory(struct mem_cgroup *memcg, gfp_t gfp_mask,
 	struct task_struct *chosen = NULL;
 
 	/*
-	 * If current has a pending SIGKILL, then automatically select it.  The
-	 * goal is to allow it to allocate so that it may quickly exit and free
-	 * its memory.
+	 * If current has a pending SIGKILL or is exiting, then automatically
+	 * select it.  The goal is to allow it to allocate so that it may
+	 * quickly exit and free its memory.
 	 */
-	if (fatal_signal_pending(current)) {
+	if (fatal_signal_pending(current) || current->flags & PF_EXITING) {
 		set_thread_flag(TIF_MEMDIE);
 		return;
 	}
@@ -3114,12 +3281,12 @@ void memcg_release_cache(struct kmem_cache *s)
 
 	root = s->memcg_params->root_cache;
 	root->memcg_params->memcg_caches[id] = NULL;
-	mem_cgroup_put(memcg);
 
 	mutex_lock(&memcg->slab_caches_mutex);
 	list_del(&s->memcg_params->list);
 	mutex_unlock(&memcg->slab_caches_mutex);
 
+	mem_cgroup_put(memcg);
 out:
 	kfree(s->memcg_params);
 }
@@ -3383,7 +3550,6 @@ static void memcg_create_cache_work_func(struct work_struct *w)
 
 /*
  * Enqueue the creation of a per-memcg kmem_cache.
- * Called with rcu_read_lock.
  */
 static void __memcg_create_cache_enqueue(struct mem_cgroup *memcg,
 					 struct kmem_cache *cachep)
@@ -3391,12 +3557,8 @@ static void __memcg_create_cache_enqueue(struct mem_cgroup *memcg,
 	struct create_work *cw;
 
 	cw = kmalloc(sizeof(struct create_work), GFP_NOWAIT);
-	if (cw == NULL)
-		return;
-
-	/* The corresponding put will be done in the workqueue. */
-	if (!css_tryget(&memcg->css)) {
-		kfree(cw);
+	if (cw == NULL) {
+		css_put(&memcg->css);
 		return;
 	}
 
@@ -3452,10 +3614,9 @@ struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep,
 
 	rcu_read_lock();
 	memcg = mem_cgroup_from_task(rcu_dereference(current->mm->owner));
-	rcu_read_unlock();
 
 	if (!memcg_can_account_kmem(memcg))
-		return cachep;
+		goto out;
 
 	idx = memcg_cache_id(memcg);
 
@@ -3464,29 +3625,38 @@ struct kmem_cache *__memcg_kmem_get_cache(struct kmem_cache *cachep,
 	 * code updating memcg_caches will issue a write barrier to match this.
 	 */
 	read_barrier_depends();
-	if (unlikely(cachep->memcg_params->memcg_caches[idx] == NULL)) {
-		/*
-		 * If we are in a safe context (can wait, and not in interrupt
-		 * context), we could be be predictable and return right away.
-		 * This would guarantee that the allocation being performed
-		 * already belongs in the new cache.
-		 *
-		 * However, there are some clashes that can arrive from locking.
-		 * For instance, because we acquire the slab_mutex while doing
-		 * kmem_cache_dup, this means no further allocation could happen
-		 * with the slab_mutex held.
-		 *
-		 * Also, because cache creation issue get_online_cpus(), this
-		 * creates a lock chain: memcg_slab_mutex -> cpu_hotplug_mutex,
-		 * that ends up reversed during cpu hotplug. (cpuset allocates
-		 * a bunch of GFP_KERNEL memory during cpuup). Due to all that,
-		 * better to defer everything.
-		 */
-		memcg_create_cache_enqueue(memcg, cachep);
-		return cachep;
+	if (likely(cachep->memcg_params->memcg_caches[idx])) {
+		cachep = cachep->memcg_params->memcg_caches[idx];
+		goto out;
 	}
 
-	return cachep->memcg_params->memcg_caches[idx];
+	/* The corresponding put will be done in the workqueue. */
+	if (!css_tryget(&memcg->css))
+		goto out;
+	rcu_read_unlock();
+
+	/*
+	 * If we are in a safe context (can wait, and not in interrupt
+	 * context), we could be be predictable and return right away.
+	 * This would guarantee that the allocation being performed
+	 * already belongs in the new cache.
+	 *
+	 * However, there are some clashes that can arrive from locking.
+	 * For instance, because we acquire the slab_mutex while doing
+	 * kmem_cache_dup, this means no further allocation could happen
+	 * with the slab_mutex held.
+	 *
+	 * Also, because cache creation issue get_online_cpus(), this
+	 * creates a lock chain: memcg_slab_mutex -> cpu_hotplug_mutex,
+	 * that ends up reversed during cpu hotplug. (cpuset allocates
+	 * a bunch of GFP_KERNEL memory during cpuup). Due to all that,
+	 * better to defer everything.
+	 */
+	memcg_create_cache_enqueue(memcg, cachep);
+	return cachep;
+out:
+	rcu_read_unlock();
+	return cachep;
 }
 EXPORT_SYMBOL(__memcg_kmem_get_cache);
 
@@ -4948,9 +5118,6 @@ static ssize_t mem_cgroup_read(struct cgroup *cont, struct cftype *cft,
 	type = MEMFILE_TYPE(cft->private);
 	name = MEMFILE_ATTR(cft->private);
 
-	if (!do_swap_account && type == _MEMSWAP)
-		return -EOPNOTSUPP;
-
 	switch (type) {
 	case _MEM:
 		if (name == RES_USAGE)
@@ -4975,6 +5142,107 @@ static ssize_t mem_cgroup_read(struct cgroup *cont, struct cftype *cft,
 	return simple_read_from_buffer(buf, nbytes, ppos, str, len);
 }
 
+#ifdef CONFIG_MEMCG_DEBUG_ASYNC_DESTROY
+static void
+mem_cgroup_dangling_swap(struct mem_cgroup *memcg, struct seq_file *m)
+{
+#ifdef CONFIG_MEMCG_SWAP
+	u64 kmem;
+	u64 memsw;
+
+	/*
+	 * kmem will also propagate here, so we are only interested in the
+	 * difference.  See comment in mem_cgroup_reparent_charges for details.
+	 *
+	 * We could save this value for later consumption by kmem reports, but
+	 * there is not a lot of problem if the figures differ slightly.
+	 */
+	kmem = res_counter_read_u64(&memcg->kmem, RES_USAGE);
+	memsw = res_counter_read_u64(&memcg->memsw, RES_USAGE) - kmem;
+	seq_printf(m, "\t%llu swap bytes\n", memsw);
+#endif
+}
+
+
+static void
+mem_cgroup_dangling_tcp(struct mem_cgroup *memcg, struct seq_file *m)
+{
+#if defined(CONFIG_INET) && defined(CONFIG_MEMCG_KMEM)
+	struct tcp_memcontrol *tcp = &memcg->tcp_mem;
+	s64 tcp_socks;
+	u64 tcp_bytes;
+
+	tcp_socks = percpu_counter_sum_positive(&tcp->tcp_sockets_allocated);
+	tcp_bytes = res_counter_read_u64(&tcp->tcp_memory_allocated, RES_USAGE);
+	seq_printf(m, "\t%llu tcp bytes", tcp_bytes);
+	/*
+	 * if tcp_bytes == 0, tcp_socks != 0 is a bug. One more reason to print
+	 * it!
+	 */
+	if (tcp_bytes || tcp_socks)
+		seq_printf(m, ", in %lld sockets", tcp_socks);
+	seq_printf(m, "\n");
+
+#endif
+}
+
+static void
+mem_cgroup_dangling_kmem(struct mem_cgroup *memcg, struct seq_file *m)
+{
+#ifdef CONFIG_MEMCG_KMEM
+	u64 kmem;
+	struct memcg_cache_params *params;
+
+	kmem = res_counter_read_u64(&memcg->kmem, RES_USAGE);
+	seq_printf(m, "\t%llu kmem bytes", kmem);
+
+	/* list below may not be initialized, so not even try */
+	if (!kmem)
+		return;
+
+	seq_printf(m, " in caches");
+	mutex_lock(&memcg->slab_caches_mutex);
+	list_for_each_entry(params, &memcg->memcg_slab_caches, list) {
+			struct kmem_cache *s = memcg_params_to_cache(params);
+
+		seq_printf(m, " %s", s->name);
+	}
+	mutex_unlock(&memcg->slab_caches_mutex);
+	seq_printf(m, "\n");
+#endif
+}
+
+/*
+ * After a memcg is destroyed, it may still be kept around in memory.
+ * Currently, the two main reasons for it are swap entries, and kernel memory.
+ * Because they will be freed assynchronously, they will pin the memcg structure
+ * and its resources until the last reference goes away.
+ *
+ * This root-only file will show information about which users
+ */
+static int mem_cgroup_dangling_read(struct cgroup *cont, struct cftype *cft,
+					struct seq_file *m)
+{
+	struct mem_cgroup *memcg;
+
+	mutex_lock(&dangling_memcgs_mutex);
+
+	list_for_each_entry(memcg, &dangling_memcgs, dead) {
+		if (memcg->memcg_name)
+			seq_printf(m, "%s:\n", memcg->memcg_name);
+		else
+			seq_printf(m, "%p (name lost):\n", memcg);
+
+		mem_cgroup_dangling_swap(memcg, m);
+		mem_cgroup_dangling_tcp(memcg, m);
+		mem_cgroup_dangling_kmem(memcg, m);
+	}
+
+	mutex_unlock(&dangling_memcgs_mutex);
+	return 0;
+}
+#endif
+
 static int memcg_update_kmem_limit(struct cgroup *cont, u64 val)
 {
 	int ret = -EINVAL;
@@ -5085,9 +5353,6 @@ static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft,
 	type = MEMFILE_TYPE(cft->private);
 	name = MEMFILE_ATTR(cft->private);
 
-	if (!do_swap_account && type == _MEMSWAP)
-		return -EOPNOTSUPP;
-
 	switch (name) {
 	case RES_LIMIT:
 		if (mem_cgroup_is_root(memcg)) { /* Can't set limit on root */
@@ -5164,9 +5429,6 @@ static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
 	type = MEMFILE_TYPE(event);
 	name = MEMFILE_ATTR(event);
 
-	if (!do_swap_account && type == _MEMSWAP)
-		return -EOPNOTSUPP;
-
 	switch (name) {
 	case RES_MAX_USAGE:
 		if (type == _MEM)
@@ -5745,7 +6007,7 @@ static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss)
 		return ret;
 
 	return mem_cgroup_sockets_init(memcg, ss);
-};
+}
 
 static void kmem_cgroup_destroy(struct mem_cgroup *memcg)
 {
@@ -5840,6 +6102,11 @@ static struct cftype mem_cgroup_files[] = {
 		.unregister_event = mem_cgroup_oom_unregister_event,
 		.private = MEMFILE_PRIVATE(_OOM_TYPE, OOM_CONTROL),
 	},
+	{
+		.name = "pressure_level",
+		.register_event = vmpressure_register_event,
+		.unregister_event = vmpressure_unregister_event,
+	},
 #ifdef CONFIG_NUMA
 	{
 		.name = "numa_stat",
@@ -5877,6 +6144,14 @@ static struct cftype mem_cgroup_files[] = {
 	},
 #endif
 #endif
+
+#ifdef CONFIG_MEMCG_DEBUG_ASYNC_DESTROY
+	{
+		.name = "dangling_memcgs",
+		.read_seq_string = mem_cgroup_dangling_read,
+		.flags = CFTYPE_ONLY_ON_ROOT,
+	},
+#endif
 	{ },	/* terminate */
 };
 
@@ -6026,6 +6301,8 @@ static void free_work(struct work_struct *work)
 	struct mem_cgroup *memcg;
 
 	memcg = container_of(work, struct mem_cgroup, work_freeing);
+
+	memcg_dangling_free(memcg);
 	__mem_cgroup_free(memcg);
 }
 
@@ -6121,6 +6398,7 @@ mem_cgroup_css_alloc(struct cgroup *cont)
 	memcg->move_charge_at_immigrate = 0;
 	mutex_init(&memcg->thresholds_lock);
 	spin_lock_init(&memcg->move_lock);
+	vmpressure_init(&memcg->vmpressure);
 
 	return &memcg->css;
 
@@ -6186,10 +6464,29 @@ mem_cgroup_css_online(struct cgroup *cont)
 	return error;
 }
 
+/*
+ * Announce all parents that a group from their hierarchy is gone.
+ */
+static void mem_cgroup_invalidate_reclaim_iterators(struct mem_cgroup *memcg)
+{
+	struct mem_cgroup *parent = memcg;
+
+	while ((parent = parent_mem_cgroup(parent)))
+		atomic_inc(&parent->dead_count);
+
+	/*
+	 * if the root memcg is not hierarchical we have to check it
+	 * explicitely.
+	 */
+	if (!root_mem_cgroup->use_hierarchy)
+		atomic_inc(&root_mem_cgroup->dead_count);
+}
+
 static void mem_cgroup_css_offline(struct cgroup *cont)
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
 
+	mem_cgroup_invalidate_reclaim_iterators(memcg);
 	mem_cgroup_reparent_charges(memcg);
 	mem_cgroup_destroy_all_caches(memcg);
 }
@@ -6200,6 +6497,7 @@ static void mem_cgroup_css_free(struct cgroup *cont)
 
 	kmem_cgroup_destroy(memcg);
 
+	memcg_dangling_add(memcg);
 	mem_cgroup_put(memcg);
 }