From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010asp101.postini.com [74.125.245.221]) by kanga.kvack.org (Postfix) with SMTP id 2DDF26B0044 for ; Thu, 8 Mar 2012 23:27:29 -0500 (EST) Received: from m2.gw.fujitsu.co.jp (unknown [10.0.50.72]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id F10DF3EE0BB for ; Fri, 9 Mar 2012 13:21:49 +0900 (JST) Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id D755B45DE52 for ; Fri, 9 Mar 2012 13:21:49 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id B867545DE4D for ; Fri, 9 Mar 2012 13:21:49 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id A36441DB803C for ; Fri, 9 Mar 2012 13:21:49 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.240.81.145]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 58CC01DB803A for ; Fri, 9 Mar 2012 13:21:49 +0900 (JST) Date: Fri, 9 Mar 2012 13:20:16 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH] memcg: Free spare array to avoid memory leak Message-Id: <20120309132016.e372a2ef.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <4F598204.9030504@gmail.com> References: <1331036004-7550-1-git-send-email-handai.szj@taobao.com> <20120309124021.810f5267.kamezawa.hiroyu@jp.fujitsu.com> <4F598204.9030504@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Sha Zhengju Cc: linux-mm@kvack.org, cgroups@vger.kernel.org, kirill@shutemov.name, Sha Zhengju On Fri, 09 Mar 2012 12:07:32 +0800 Sha Zhengju wrote: > On 03/09/2012 11:40 AM, KAMEZAWA Hiroyuki wrote: > > On Tue, 6 Mar 2012 20:13:24 +0800 > > Sha Zhengju wrote: > > > >> From: Sha Zhengju > >> > >> When the last event is unregistered, there is no need to keep the spare > >> array anymore. So free it to avoid memory leak. > >> > >> Signed-off-by: Sha Zhengju > >> > >> --- > >> mm/memcontrol.c | 6 ++++++ > >> 1 files changed, 6 insertions(+), 0 deletions(-) > >> > >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c > >> index 22d94f5..3c09a84 100644 > >> --- a/mm/memcontrol.c > >> +++ b/mm/memcontrol.c > >> @@ -4412,6 +4412,12 @@ static void mem_cgroup_usage_unregister_event(struct cgroup *cgrp, > >> swap_buffers: > >> /* Swap primary and spare array */ > >> thresholds->spare = thresholds->primary; > >> + /* If all events are unregistered, free the spare array */ > >> + if (!new) { > >> + kfree(thresholds->spare); > >> + thresholds->spare = NULL; > >> + } > >> + > > Could you clear thresholds->primary ? I don't like a pointer points to freed memory. > Do you meaning I should set ‘thresholds->primary = NULL‘ ？ > But the following rcu_assign_pointer will do this : > > + /* If all events are unregistered, free the spare array */ > + if (!new) { > + kfree(thresholds->spare); > + thresholds->spare = NULL; > + } > + > rcu_assign_pointer(thresholds->primary, new);<---------*HERE* > Hm, ok. Acked-by: KAMEZAWA Hiroyuki BTW, can memory cgroup be destroyed while there are registered events ? -- 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