From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail144.messagelabs.com (mail144.messagelabs.com [216.82.254.51]) by kanga.kvack.org (Postfix) with SMTP id 4729A6B0074 for ; Tue, 16 Dec 2008 01:01:31 -0500 (EST) Received: from m3.gw.fujitsu.co.jp ([10.0.50.73]) by fgwmail6.fujitsu.co.jp (Fujitsu Gateway) with ESMTP id mBG62xAu027643 for (envelope-from kamezawa.hiroyu@jp.fujitsu.com); Tue, 16 Dec 2008 15:03:00 +0900 Received: from smail (m3 [127.0.0.1]) by outgoing.m3.gw.fujitsu.co.jp (Postfix) with ESMTP id B673B45DD7F for ; Tue, 16 Dec 2008 15:02:59 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (s3.gw.fujitsu.co.jp [10.0.50.93]) by m3.gw.fujitsu.co.jp (Postfix) with ESMTP id 93BB045DD7B for ; Tue, 16 Dec 2008 15:02:59 +0900 (JST) Received: from s3.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 6C0881DB803F for ; Tue, 16 Dec 2008 15:02:59 +0900 (JST) Received: from ml14.s.css.fujitsu.com (ml14.s.css.fujitsu.com [10.249.87.104]) by s3.gw.fujitsu.co.jp (Postfix) with ESMTP id 21D481DB803B for ; Tue, 16 Dec 2008 15:02:59 +0900 (JST) Date: Tue, 16 Dec 2008 15:02:02 +0900 From: KAMEZAWA Hiroyuki Subject: [BUGFIX][RFT][PATCH] memcg: fix double free in error route Message-Id: <20081216150202.bf6408ac.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: "linux-mm@kvack.org" Cc: "linux-kernel@vger.kernel.org" , "nishimura@mxp.nes.nec.co.jp" , "balbir@linux.vnet.ibm.com" List-ID: Could you test this ? This includes a fix and a cleanup. After this, the kernel will panic if handling of refcnt is bad. This is against mmotom-dec-15. == From: KAMEZAWA Hiroyuki 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. Singed-off-by: KAMEZAWA Hiroyuki --- Index: mmotm-2.6.28-Dec15/mm/memcontrol.c =================================================================== --- mmotm-2.6.28-Dec15.orig/mm/memcontrol.c +++ mmotm-2.6.28-Dec15/mm/memcontrol.c @@ -2087,14 +2087,10 @@ 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); @@ -2111,11 +2107,8 @@ 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); } @@ -2165,12 +2158,10 @@ 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); } @@ -2185,7 +2176,7 @@ 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, -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org