1 files changed, 42 insertions, 30 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 795e525afaba..07d92b84f448 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3739,27 +3739,21 @@ static bool mem_cgroup_force_empty_list(struct mem_cgroup *memcg,
 }
 
 /*
- * make mem_cgroup's charge to be 0 if there is no task.
+ * make mem_cgroup's charge to be 0 if there is no task by moving
+ * all the charges and pages to the parent.
  * This enables deleting this mem_cgroup.
+ *
+ * Caller is responsible for holding css reference on the memcg.
  */
-static int mem_cgroup_force_empty(struct mem_cgroup *memcg, bool free_all)
+static int mem_cgroup_reparent_charges(struct mem_cgroup *memcg)
 {
-        int ret;
-        int node, zid, shrink;
-        int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
         struct cgroup *cgrp = memcg->css.cgroup;
+        int node, zid;
+        int ret;
 
-        css_get(&memcg->css);
-
-        shrink = 0;
-        /* should free all ? */
-        if (free_all)
-                goto try_to_free;
-move_account:
         do {
-                ret = -EBUSY;
                 if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children))
-                        goto out;
+                        return -EBUSY;
                 /* This is for making all *used* pages to be on LRU. */
                 lru_add_drain_all();
                 drain_all_stock_sync(memcg);
@@ -3783,27 +3777,34 @@ move_account:
                 cond_resched();
         /* "ret" should also be checked to ensure all lists are empty. */
         } while (res_counter_read_u64(&memcg->res, RES_USAGE) > 0 || ret);
-out:
-        css_put(&memcg->css);
+
         return ret;
+}
+
+/*
+ * Reclaims as many pages from the given memcg as possible and moves
+ * the rest to the parent.
+ *
+ * Caller is responsible for holding css reference for memcg.
+ */
+static int mem_cgroup_force_empty(struct mem_cgroup *memcg)
+{
+        int nr_retries = MEM_CGROUP_RECLAIM_RETRIES;
+        struct cgroup *cgrp = memcg->css.cgroup;
 
-try_to_free:
         /* 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;
-        }
+        if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children))
+                return -EBUSY;
+
         /* 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 && res_counter_read_u64(&memcg->res, RES_USAGE) > 0) {
                 int progress;
 
-                if (signal_pending(current)) {
-                        ret = -EINTR;
-                        goto out;
-                }
+                if (signal_pending(current))
+                        return -EINTR;
+
                 progress = try_to_free_mem_cgroup_pages(memcg, GFP_KERNEL,
                                                 false);
                 if (!progress) {
@@ -3814,13 +3815,19 @@ try_to_free:
 
         }
         lru_add_drain();
-        /* try move_account...there may be some *locked* pages. */
-        goto move_account;
+        return mem_cgroup_reparent_charges(memcg);
 }
 
 static int mem_cgroup_force_empty_write(struct cgroup *cont, unsigned int event)
 {
-        return mem_cgroup_force_empty(mem_cgroup_from_cont(cont), true);
+        struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+        int ret;
+
+        css_get(&memcg->css);
+        ret = mem_cgroup_force_empty(memcg);
+        css_put(&memcg->css);
+
+        return ret;
 }
 
 
@@ -5003,8 +5010,13 @@ free_out:
 static int mem_cgroup_pre_destroy(struct cgroup *cont)
 {
         struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
+        int ret;
 
-        return mem_cgroup_force_empty(memcg, false);
+        css_get(&memcg->css);
+        ret = mem_cgroup_reparent_charges(memcg);
+        css_put(&memcg->css);
+
+        return ret;
 }
 
 static void mem_cgroup_destroy(struct cgroup *cont)