1 files changed, 34 insertions, 7 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index e00f25e..decace3 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1062,21 +1062,27 @@ static int mem_cgroup_force_empty_list(struct mem_cgroup *mem,
  * make mem_cgroup's charge to be 0 if there is no task.
  * This enables deleting this mem_cgroup.
  */
-static int mem_cgroup_force_empty(struct mem_cgroup *mem)
+static int mem_cgroup_force_empty(struct mem_cgroup *mem, bool free_all)
 {
 	int ret;
 	int node, zid, shrink;
 	int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
+	struct cgroup *cgrp = mem->css.cgroup;
 
 	css_get(&mem->css);
 
 	shrink = 0;
+	/* should free all ? */
+	if (free_all)
+		goto try_to_free;
 move_account:
 	while (mem->res.usage > 0) {
 		ret = -EBUSY;
-		if (atomic_read(&mem->css.cgroup->count) > 0)
+		if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children))
+			goto out;
+		ret = -EINTR;
+		if (signal_pending(current))
 			goto out;
-
 		/* This is for making all *used* pages to be on LRU. */
 		lru_add_drain_all();
 		ret = 0;
@@ -1106,19 +1112,29 @@ out:
 	return ret;
 
 try_to_free:
-	/* returns EBUSY if we come here twice. */
-	if (shrink)  {
+	/* returns EBUSY if there is a task or if we come here twice. */
+	if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children) || shrink) {
 		ret = -EBUSY;
 		goto out;
 	}
+	/* we call try-to-free pages for make this cgroup empty */
+	lru_add_drain_all();
 	/* try to free all pages in this cgroup */
 	shrink = 1;
 	while (nr_retries && mem->res.usage > 0) {
 		int progress;
+
+		if (signal_pending(current)) {
+			ret = -EINTR;
+			goto out;
+		}
 		progress = try_to_free_mem_cgroup_pages(mem,
 						  GFP_HIGHUSER_MOVABLE);
-		if (!progress)
+		if (!progress) {
 			nr_retries--;
+			/* maybe some writeback is necessary */
+			congestion_wait(WRITE, HZ/10);
+		}
 
 	}
 	/* try move_account...there may be some *locked* pages. */
@@ -1128,6 +1144,12 @@ try_to_free:
 	goto out;
 }
 
+int mem_cgroup_force_empty_write(struct cgroup *cont, unsigned int event)
+{
+	return mem_cgroup_force_empty(mem_cgroup_from_cont(cont), true);
+}
+
+
 static u64 mem_cgroup_read(struct cgroup *cont, struct cftype *cft)
 {
 	return res_counter_read_u64(&mem_cgroup_from_cont(cont)->res,
@@ -1225,6 +1247,7 @@ static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft,
 	return 0;
 }
 
+
 static struct cftype mem_cgroup_files[] = {
 	{
 		.name = "usage_in_bytes",
@@ -1253,6 +1276,10 @@ static struct cftype mem_cgroup_files[] = {
 		.name = "stat",
 		.read_map = mem_control_stat_show,
 	},
+	{
+		.name = "force_empty",
+		.trigger = mem_cgroup_force_empty_write,
+	},
 };
 
 static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
@@ -1350,7 +1377,7 @@ static void mem_cgroup_pre_destroy(struct cgroup_subsys *ss,
 					struct cgroup *cont)
 {
 	struct mem_cgroup *mem = mem_cgroup_from_cont(cont);
-	mem_cgroup_force_empty(mem);
+	mem_cgroup_force_empty(mem, false);
 }
 
 static void mem_cgroup_destroy(struct cgroup_subsys *ss,