---

yaml
---
r: 190683
b: refs/heads/master
c: ad4ba37
h: refs/heads/master
i:
  190681: 430517d
  190679: 3d3ecd4
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 1ce7e4ff24fe338438bc7837e02780f202bf202b
+refs/heads/master: ad4ba375373937817404fd92239ef4cadbded23b

trunk/mm/memcontrol.c

@@ -811,10 +811,12 @@ int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem)
 	 * enabled in "curr" and "curr" is a child of "mem" in *cgroup*
 	 * hierarchy(even if use_hierarchy is disabled in "mem").
 	 */
+	rcu_read_lock();
 	if (mem->use_hierarchy)
 		ret = css_is_ancestor(&curr->css, &mem->css);
 	else
 		ret = (curr == mem);
+	rcu_read_unlock();
 	css_put(&curr->css);
 	return ret;
 }
@@ -2312,7 +2314,9 @@ mem_cgroup_uncharge_swapcache(struct page *page, swp_entry_t ent, bool swapout)
 
 	/* record memcg information */
 	if (do_swap_account && swapout && memcg) {
+		rcu_read_lock();
 		swap_cgroup_record(ent, css_id(&memcg->css));
+		rcu_read_unlock();
 		mem_cgroup_get(memcg);
 	}
 	if (swapout && memcg)
@@ -2369,8 +2373,10 @@ static int mem_cgroup_move_swap_account(swp_entry_t entry,
 {
 	unsigned short old_id, new_id;
 
+	rcu_read_lock();
 	old_id = css_id(&from->css);
 	new_id = css_id(&to->css);
+	rcu_read_unlock();
 
 	if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
 		mem_cgroup_swap_statistics(from, false);
@@ -4038,11 +4044,16 @@ static int is_target_pte_for_mc(struct vm_area_struct *vma,
 			put_page(page);
 	}
 	/* throught */
-	if (ent.val && do_swap_account && !ret &&
-			css_id(&mc.from->css) == lookup_swap_cgroup(ent)) {
-		ret = MC_TARGET_SWAP;
-		if (target)
-			target->ent = ent;
+	if (ent.val && do_swap_account && !ret) {
+		unsigned short id;
+		rcu_read_lock();
+		id = css_id(&mc.from->css);
+		rcu_read_unlock();
+		if (id == lookup_swap_cgroup(ent)) {
+			ret = MC_TARGET_SWAP;
+			if (target)
+				target->ent = ent;
+		}
 	}
 	return ret;
 }