From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail191.messagelabs.com (mail191.messagelabs.com [216.82.242.19]) by kanga.kvack.org (Postfix) with ESMTP id EB63E6B0055 for ; Thu, 24 Sep 2009 01:52:11 -0400 (EDT) Date: Thu, 24 Sep 2009 14:49:02 +0900 From: Daisuke Nishimura Subject: [RFC][PATCH 6/8] memcg: avoid oom during charge migration Message-Id: <20090924144902.f4e5854c.nishimura@mxp.nes.nec.co.jp> In-Reply-To: <20090924144214.508469d1.nishimura@mxp.nes.nec.co.jp> References: <20090917112304.6cd4e6f6.nishimura@mxp.nes.nec.co.jp> <20090917160103.1bcdddee.nishimura@mxp.nes.nec.co.jp> <20090924144214.508469d1.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 | 19 +++++++++++++++++++ 1 files changed, 19 insertions(+), 0 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index fbcc195..25de11c 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -287,6 +287,8 @@ struct migrate_charge { unsigned long precharge; }; 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); @@ -1317,6 +1319,7 @@ 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; @@ -1358,6 +1361,17 @@ 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 (mc_task && 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); @@ -3345,6 +3359,8 @@ static void mem_cgroup_clear_migrate_charge(void) __mem_cgroup_cancel_charge(mc->to); kfree(mc); mc = NULL; + mc_task = NULL; + wake_up_all(&mc_waitq); } static int mem_cgroup_can_migrate_charge(struct mem_cgroup *mem, @@ -3354,6 +3370,7 @@ 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; @@ -3367,6 +3384,8 @@ static int mem_cgroup_can_migrate_charge(struct mem_cgroup *mem, mc->to = mem; mc->precharge = 0; + mc_task = current; + ret = migrate_charge_prepare(); if (ret) -- 1.5.6.1 -- 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