From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752328Ab2JHKH5 (ORCPT ); Mon, 8 Oct 2012 06:07:57 -0400 Received: from mailhub.sw.ru ([195.214.232.25]:26105 "EHLO relay.sw.ru" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751612Ab2JHKHy (ORCPT ); Mon, 8 Oct 2012 06:07:54 -0400 From: Glauber Costa To: Cc: , Andrew Morton , Mel Gorman , Suleiman Souhlal , Tejun Heo , , , Michal Hocko , Johannes Weiner , Greg Thelen , , Frederic Weisbecker , Glauber Costa , Christoph Lameter , Pekka Enberg Subject: [PATCH v4 11/14] memcg: allow a memcg with kmem charges to be destructed. Date: Mon, 8 Oct 2012 14:06:17 +0400 Message-Id: <1349690780-15988-12-git-send-email-glommer@parallels.com> X-Mailer: git-send-email 1.7.11.4 In-Reply-To: <1349690780-15988-1-git-send-email-glommer@parallels.com> References: <1349690780-15988-1-git-send-email-glommer@parallels.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Because the ultimate goal of the kmem tracking in memcg is to track slab pages as well, we can't guarantee that we'll always be able to point a page to a particular process, and migrate the charges along with it - since in the common case, a page will contain data belonging to multiple processes. Because of that, when we destroy a memcg, we only make sure the destruction will succeed by discounting the kmem charges from the user charges when we try to empty the cgroup. Signed-off-by: Glauber Costa Acked-by: Kamezawa Hiroyuki Reviewed-by: Michal Hocko CC: Christoph Lameter CC: Pekka Enberg CC: Johannes Weiner CC: Suleiman Souhlal --- mm/memcontrol.c | 17 ++++++++++++++++- 1 file changed, 16 insertions(+), 1 deletion(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 724a08b..2f92f89 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -546,6 +546,11 @@ static void disarm_kmem_keys(struct mem_cgroup *memcg) { if (memcg_kmem_is_active(memcg)) static_key_slow_dec(&memcg_kmem_enabled_key); + /* + * This check can't live in kmem destruction function, + * since the charges will outlive the cgroup + */ + WARN_ON(res_counter_read_u64(&memcg->kmem, RES_USAGE) != 0); } #else static void disarm_kmem_keys(struct mem_cgroup *memcg) @@ -3994,6 +3999,7 @@ static int mem_cgroup_force_empty(struct mem_cgroup *memcg, bool free_all) int node, zid, shrink; int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; struct cgroup *cgrp = memcg->css.cgroup; + u64 usage; css_get(&memcg->css); @@ -4027,8 +4033,17 @@ move_account: mem_cgroup_end_move(memcg); memcg_oom_recover(memcg); cond_resched(); + /* + * Kernel memory may not necessarily be trackable to a specific + * process. So they are not migrated, and therefore we can't + * expect their value to drop to 0 here. + * + * having res filled up with kmem only is enough + */ + usage = res_counter_read_u64(&memcg->res, RES_USAGE) - + res_counter_read_u64(&memcg->kmem, RES_USAGE); /* "ret" should also be checked to ensure all lists are empty. */ - } while (res_counter_read_u64(&memcg->res, RES_USAGE) > 0 || ret); + } while (usage > 0 || ret); out: css_put(&memcg->css); return ret; -- 1.7.11.4