memcg: fix double free and make refcnt sane
1. Fix double-free BUG in error route of mem_cgroup_create().
mem_cgroup_free() itself frees per-zone-info.
2. Making refcnt of memcg simple.
Add 1 refcnt at creation and call free when refcnt goes down to 0.
Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 0ed61e2..4f9a9c5 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2092,14 +2092,10 @@
* Removal of cgroup itself succeeds regardless of refs from swap.
*/
-static void mem_cgroup_free(struct mem_cgroup *mem)
+static void __mem_cgroup_free(struct mem_cgroup *mem)
{
int node;
- if (atomic_read(&mem->refcnt) > 0)
- return;
-
-
for_each_node_state(node, N_POSSIBLE)
free_mem_cgroup_per_zone_info(mem, node);
@@ -2116,11 +2112,8 @@
static void mem_cgroup_put(struct mem_cgroup *mem)
{
- if (atomic_dec_and_test(&mem->refcnt)) {
- if (!mem->obsolete)
- return;
- mem_cgroup_free(mem);
- }
+ if (atomic_dec_and_test(&mem->refcnt))
+ __mem_cgroup_free(mem);
}
@@ -2170,12 +2163,10 @@
if (parent)
mem->swappiness = get_swappiness(parent);
-
+ atomic_set(&mem->refcnt, 1);
return &mem->css;
free_out:
- for_each_node_state(node, N_POSSIBLE)
- free_mem_cgroup_per_zone_info(mem, node);
- mem_cgroup_free(mem);
+ __mem_cgroup_free(mem);
return ERR_PTR(-ENOMEM);
}
@@ -2190,7 +2181,7 @@
static void mem_cgroup_destroy(struct cgroup_subsys *ss,
struct cgroup *cont)
{
- mem_cgroup_free(mem_cgroup_from_cont(cont));
+ mem_cgroup_put(mem_cgroup_from_cont(cont));
}
static int mem_cgroup_populate(struct cgroup_subsys *ss,