Messages in this thread Patch in this message | | | Date | Thu, 18 Dec 2008 17:58:10 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | [PATCH 1/2] memcg: fix double free and make refcnt sane |
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From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
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> Singed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> --- Index: mmotm-2.6.28-Dec16/mm/memcontrol.c =================================================================== --- mmotm-2.6.28-Dec16.orig/mm/memcontrol.c +++ mmotm-2.6.28-Dec16/mm/memcontrol.c @@ -2085,14 +2085,10 @@ static struct mem_cgroup *mem_cgroup_all * 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); @@ -2109,11 +2105,8 @@ static void mem_cgroup_get(struct mem_cg 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); } @@ -2163,12 +2156,10 @@ mem_cgroup_create(struct cgroup_subsys * 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); } @@ -2183,7 +2174,7 @@ static void mem_cgroup_pre_destroy(struc 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,
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