From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx193.postini.com [74.125.245.193]) by kanga.kvack.org (Postfix) with SMTP id CBCEB6B002C for ; Wed, 7 Mar 2012 22:14:52 -0500 (EST) Received: by iajr24 with SMTP id r24so95541iaj.14 for ; Wed, 07 Mar 2012 19:14:52 -0800 (PST) Date: Wed, 7 Mar 2012 19:14:49 -0800 (PST) From: David Rientjes Subject: [patch] mm, memcg: do not allow tasks to be attached with zero limit Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Johannes Weiner , Michal Hocko , Balbir Singh , KAMEZAWA Hiroyuki , cgroups@vger.kernel.org, linux-mm@kvack.org This patch prevents tasks from being attached to a memcg if there is a hard limit of zero. Additionally, the hard limit may not be changed to zero if there are tasks attached. This is consistent with cpusets which do not allow tasks to be attached if there are no mems and prevents all mems from being removed if there are tasks attached. Signed-off-by: David Rientjes --- mm/memcontrol.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -3868,9 +3868,14 @@ static int mem_cgroup_write(struct cgroup *cont, struct cftype *cft, ret = res_counter_memparse_write_strategy(buffer, &val); if (ret) break; - if (type == _MEM) + if (type == _MEM) { + /* Don't allow zero limit with tasks attached */ + if (!val && cgroup_task_count(cont)) { + ret = -ENOSPC; + break; + } ret = mem_cgroup_resize_limit(memcg, val); - else + } else ret = mem_cgroup_resize_memsw_limit(memcg, val); break; case RES_SOFT_LIMIT: @@ -5306,6 +5311,10 @@ static int mem_cgroup_can_attach(struct cgroup_subsys *ss, int ret = 0; struct mem_cgroup *memcg = mem_cgroup_from_cont(cgroup); + /* Don't allow tasks attached with a zero limit */ + if (!res_counter_read_u64(&memcg->res, RES_LIMIT)) + return -ENOSPC; + if (memcg->move_charge_at_immigrate) { struct mm_struct *mm; struct mem_cgroup *from = mem_cgroup_from_task(p); -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org