From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751432Ab2GIFLS (ORCPT ); Mon, 9 Jul 2012 01:11:18 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:50851 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750814Ab2GIFLR (ORCPT ); Mon, 9 Jul 2012 01:11:17 -0400 Date: Mon, 9 Jul 2012 13:10:55 +0800 From: Wanpeng Li To: Kamezawa Hiroyuki Cc: Johannes Weiner , Michal Hocko , Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Wanpeng Li Subject: Re: [PATCH] mm/memcg: return -EBUSY when oom-kill-disable modified and memcg use_hierarchy, has children Message-ID: <20120709051036.GA8304@kernel> Reply-To: Wanpeng Li References: <1341485708-14221-1-git-send-email-liwp.linux@gmail.com> <4FFA616B.4000608@jp.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4FFA616B.4000608@jp.fujitsu.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jul 09, 2012 at 01:43:23PM +0900, Kamezawa Hiroyuki wrote: >(2012/07/05 19:55), Wanpeng Li wrote: >> From: Wanpeng Li >> >> When oom-kill-disable modified by the user and current memcg use_hierarchy, >> the change can occur, provided the current memcg has no children. If it >> has children, return -EBUSY is enough. >> >> Signed-off-by: Wanpeng Li > >I'm sorry what is the point ? You think -EBUSY should be returned in this case >rather than -EINVAl ? Then, why ? just like in function cmem_cgroup_hierarchy_write: if((!parent_memcg || !parent_memcg->use_hierarchy) && (val == 1 || val == 0) { if (list_empty(&cont->children)) memcg->use_hierarchy = val; else return -EBUSY; } else return = -EINVAL; If memcg->use_hierarchy && has children memcg, the user can try again if children memcg disappear. Or I miss something .... Regards, Wanpeng Li > > >> --- >> mm/memcontrol.c | 7 +++++-- >> 1 files changed, 5 insertions(+), 2 deletions(-) >> >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c >> index 63e36e7..4b64fe0 100644 >> --- a/mm/memcontrol.c >> +++ b/mm/memcontrol.c >> @@ -4521,11 +4521,14 @@ static int mem_cgroup_oom_control_write(struct cgroup *cgrp, >> >> cgroup_lock(); >> /* oom-kill-disable is a flag for subhierarchy. */ >> - if ((parent->use_hierarchy) || >> - (memcg->use_hierarchy && !list_empty(&cgrp->children))) { >> + if (parent->use_hierarchy) { >> cgroup_unlock(); >> return -EINVAL; >> + } else if (memcg->use_hierarchy && !list_empty(&cgrp->children)) { >> + cgroup_unlock(); >> + return -EBUSY; >> } >> + >> memcg->oom_kill_disable = val; >> if (!val) >> memcg_oom_recover(memcg); >> > >