From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with ESMTP id 3F9046B0055 for ; Wed, 16 Sep 2009 23:12:49 -0400 (EDT) Date: Thu, 17 Sep 2009 11:29:17 +0900 From: Daisuke Nishimura Subject: [PATCH 8/8] memcg: avoid oom during charge migration Message-Id: <20090917112917.3d766f8c.nishimura@mxp.nes.nec.co.jp> In-Reply-To: <20090917112304.6cd4e6f6.nishimura@mxp.nes.nec.co.jp> References: <20090917112304.6cd4e6f6.nishimura@mxp.nes.nec.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: linux-mm Cc: Balbir Singh , KAMEZAWA Hiroyuki , Paul Menage , Li Zefan , Daisuke Nishimura List-ID: This charge migration feature has double charges on both "from" and "to" mem_cgroup during charge migration. This means unnecessary oom can happen because of charge migration. This patch tries to avoid such oom. Signed-off-by: Daisuke Nishimura --- mm/memcontrol.c | 18 ++++++++++++++++++ 1 files changed, 18 insertions(+), 0 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index c8542e7..73da7e7 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -288,6 +288,8 @@ struct migrate_charge { struct list_head list; }; static struct migrate_charge *mc; +static struct task_struct *mc_task; +static DECLARE_WAIT_QUEUE_HEAD(mc_waitq); static void mem_cgroup_get(struct mem_cgroup *mem); static void mem_cgroup_put(struct mem_cgroup *mem); @@ -1318,6 +1320,7 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm, while (1) { int ret = 0; unsigned long flags = 0; + DEFINE_WAIT(wait); if (mem_cgroup_is_root(mem)) goto done; @@ -1359,6 +1362,17 @@ static int __mem_cgroup_try_charge(struct mm_struct *mm, if (mem_cgroup_check_under_limit(mem_over_limit)) continue; + /* try to avoid oom while someone is migrating charge */ + if (current != mc_task) { + prepare_to_wait(&mc_waitq, &wait, TASK_INTERRUPTIBLE); + if (mc) { + schedule(); + finish_wait(&mc_waitq, &wait); + continue; + } + finish_wait(&mc_waitq, &wait); + } + if (!nr_retries--) { if (oom) { mutex_lock(&memcg_tasklist); @@ -3432,6 +3446,8 @@ static void mem_cgroup_clear_migrate_charge(void) kfree(mc); mc = NULL; + mc_task = NULL; + wake_up_all(&mc_waitq); } static int mem_cgroup_can_migrate_charge(struct mem_cgroup *mem, @@ -3441,6 +3457,7 @@ static int mem_cgroup_can_migrate_charge(struct mem_cgroup *mem, struct mem_cgroup *from = mem_cgroup_from_task(p); VM_BUG_ON(mc); + VM_BUG_ON(mc_task); if (from == mem) return 0; @@ -3453,6 +3470,7 @@ static int mem_cgroup_can_migrate_charge(struct mem_cgroup *mem, mc->from = from; mc->to = mem; INIT_LIST_HEAD(&mc->list); + mc_task = current; ret = migrate_charge_prepare(); -- 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