From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sha Zhengju Subject: Re: [PATCH] memcg: Free spare array to avoid memory leak Date: Thu, 08 Mar 2012 10:11:32 +0800 Message-ID: <4F581554.6020801@gmail.com> References: <1331036004-7550-1-git-send-email-handai.szj@taobao.com> <20120307230819.GA10238@shutemov.name> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; bh=P6cjtSOVWU9rumvbFchyND4/soFkhGoE1lChHQ9O/yA=; b=IkWihuJRb5MwIvgJnDR3K91uuO4g825uT5D/J8huSy8eJqdhpTB/NTtKc6n86KRiZc 19yCXO6yswBsn4eVPtXfJFLG1Log49IKsS9QJIT/AYGOFlX0a4Q8PcuUKfsUXVVPAubZ 1ZbYHJZ9oK/6pSTZmyD1rT7m9oRV1dvaa8zpNPPUGP3Ygj5rOjrZgRIZq/IxSDMTzfZs 4QqJ4ZjLpRcyExW5NaL46uJhuCabDKadKgSwdSf4lxpeHKlOnwL233vGuHhlBJlfDjVi OGv1ZVc7q+Zq8d0crOq3250B6spiiZR1C4mJgGXcZiS1Y8l1RPx+58cRg1JtjPUlcb32 tWxg== In-Reply-To: <20120307230819.GA10238-oKw7cIdHH8eLwutG50LtGA@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: "Kirill A. Shutemov" Cc: linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org, Sha Zhengju On 03/08/2012 07:08 AM, Kirill A. Shutemov wrote: > On Tue, Mar 06, 2012 at 08:13:24PM +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. > It's not a leak. It will be freed on next event register. Yeah, I noticed that. But what if it is just the last one and no more event registering ? Thanks, Sha > Yeah, we don't have to keep spare if primary is empty. But is it worth to > make code more complicated to save few bytes of memory? > >> 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; >> + } >> + >> rcu_assign_pointer(thresholds->primary, new); >> >> /* To be sure that nobody uses thresholds */ >> -- >> 1.7.4.1 >> From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx137.postini.com [74.125.245.137]) by kanga.kvack.org (Postfix) with SMTP id 051326B002C for ; Wed, 7 Mar 2012 21:11:35 -0500 (EST) Received: by pbcup15 with SMTP id up15so1270686pbc.14 for ; Wed, 07 Mar 2012 18:11:35 -0800 (PST) Message-ID: <4F581554.6020801@gmail.com> Date: Thu, 08 Mar 2012 10:11:32 +0800 From: Sha Zhengju MIME-Version: 1.0 Subject: Re: [PATCH] memcg: Free spare array to avoid memory leak References: <1331036004-7550-1-git-send-email-handai.szj@taobao.com> <20120307230819.GA10238@shutemov.name> In-Reply-To: <20120307230819.GA10238@shutemov.name> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: linux-mm@kvack.org, cgroups@vger.kernel.org, kamezawa.hiroyu@jp.fujitsu.com, Sha Zhengju On 03/08/2012 07:08 AM, Kirill A. Shutemov wrote: > On Tue, Mar 06, 2012 at 08:13:24PM +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. > It's not a leak. It will be freed on next event register. Yeah, I noticed that. But what if it is just the last one and no more event registering ? Thanks, Sha > Yeah, we don't have to keep spare if primary is empty. But is it worth to > make code more complicated to save few bytes of memory? > >> 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; >> + } >> + >> rcu_assign_pointer(thresholds->primary, new); >> >> /* To be sure that nobody uses thresholds */ >> -- >> 1.7.4.1 >> -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org