memcg: split mem_cgroup_force_empty into reclaiming and reparenting parts

[GitHub/mt8127/android_kernel_alcatel_ttab.git] / mm / memcontrol.c

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 795e525afaba8914f3f8863de6a7299d84898ada..07d92b84f448107200e8851e0307fbd51fa8f6e2 100644 (file)
--- 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)