From 29577da9a826320d5142c954cad17c6bc8dfce23 Mon Sep 17 00:00:00 2001
From: Balbir Singh <balbir@linux.vnet.ibm.com>
Date: Thu, 7 Feb 2008 00:13:54 -0800
Subject: [PATCH] --- yaml --- r: 83762 b: refs/heads/master c:
 67e465a77ba658635309ee00b367bec6555ea544 h: refs/heads/master v: v3

---
 [refs]                |  2 +-
 trunk/mm/memcontrol.c | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/[refs] b/[refs]
index 00d6c88cdc60..a7c71f8ca4af 100644
--- a/[refs]
+++ b/[refs]
@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 8a9f3ccd24741b50200c3f33d62534c7271f3dfc
+refs/heads/master: 67e465a77ba658635309ee00b367bec6555ea544
diff --git a/trunk/mm/memcontrol.c b/trunk/mm/memcontrol.c
index ebca767292dc..b25df2a9d024 100644
--- a/trunk/mm/memcontrol.c
+++ b/trunk/mm/memcontrol.c
@@ -326,11 +326,46 @@ static int mem_cgroup_populate(struct cgroup_subsys *ss,
 					ARRAY_SIZE(mem_cgroup_files));
 }
 
+static void mem_cgroup_move_task(struct cgroup_subsys *ss,
+				struct cgroup *cont,
+				struct cgroup *old_cont,
+				struct task_struct *p)
+{
+	struct mm_struct *mm;
+	struct mem_cgroup *mem, *old_mem;
+
+	mm = get_task_mm(p);
+	if (mm == NULL)
+		return;
+
+	mem = mem_cgroup_from_cont(cont);
+	old_mem = mem_cgroup_from_cont(old_cont);
+
+	if (mem == old_mem)
+		goto out;
+
+	/*
+	 * Only thread group leaders are allowed to migrate, the mm_struct is
+	 * in effect owned by the leader
+	 */
+	if (p->tgid != p->pid)
+		goto out;
+
+	css_get(&mem->css);
+	rcu_assign_pointer(mm->mem_cgroup, mem);
+	css_put(&old_mem->css);
+
+out:
+	mmput(mm);
+	return;
+}
+
 struct cgroup_subsys mem_cgroup_subsys = {
 	.name = "memory",
 	.subsys_id = mem_cgroup_subsys_id,
 	.create = mem_cgroup_create,
 	.destroy = mem_cgroup_destroy,
 	.populate = mem_cgroup_populate,
+	.attach = mem_cgroup_move_task,
 	.early_init = 1,
 };