From a7ba0eef3af51cd1b6fc4028e4705b3ea2ea9469 Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki Date: Wed, 7 Jan 2009 18:08:32 -0800 Subject: [PATCH] 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 Signed-off-by: KAMEZAWA Hiroyuki Cc: Balbir Singh Cc: Paul Menage Cc: Daisuke Nishimura Cc: Li Zefan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 21 ++++++--------------- 1 file changed, 6 insertions(+), 15 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 0ed61e27d526..4f9a9c5a02e2 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2092,14 +2092,10 @@ static struct mem_cgroup *mem_cgroup_alloc(void) * 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_get(struct mem_cgroup *mem) 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 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont) 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_pre_destroy(struct cgroup_subsys *ss, 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, -- 2.30.2