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: Fri, 09 Mar 2012 12:07:32 +0800 Message-ID: <4F598204.9030504@gmail.com> References: <1331036004-7550-1-git-send-email-handai.szj@taobao.com> <20120309124021.810f5267.kamezawa.hiroyu@jp.fujitsu.com> Mime-Version: 1.0 Content-Transfer-Encoding: QUOTED-PRINTABLE 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=VEBlJdO6+PPrJ52IzIU1O1PKnfrh6gVO3A1+UjTFgHs=; b=lhtWbTJPNxo9w1bKXbL1ERHsk6rZQgUaXxtv0t2AjOGr+n79zyficLl7NDz6+4eIXe Nw6wIFATGHnd3M7/b53/FPbSiBqFuyfg8Jrmg1TDUT+jzJkwVqzrpEFEN31LseCUwqjF W89c+QGLMSt6JaMaa5N1ZCe5Cecgq+DnH9YTeOxwrgdYGC9FIvLJmnaVTOF94tbdWWa7 2mtlMwejA7D8ZtjtftiOY21dsQLttohddv5aYS759ZY7VYrF4aCmsIAPCDHAqSMScjUw ouoMMHCNvv1NLYLH5fJ8B2vjOMDcJ2ynBTaH4Lh8yRICWt6uWKe9XyPZSsEXFzuvKbUz 9WtA== In-Reply-To: <20120309124021.810f5267.kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="utf-8"; format="flowed" To: KAMEZAWA Hiroyuki Cc: linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, kirill-oKw7cIdHH8eLwutG50LtGA@public.gmane.org, Sha Zhengju 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 sp= are >> 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 =3D thresholds->primary; >> + /* If all events are unregistered, free the spare array */ >> + if (!new) { >> + kfree(thresholds->spare); >> + thresholds->spare =3D NULL; >> + } >> + > Could you clear thresholds->primary ? I don't like a pointer points t= o freed memory. Do you meaning I should set =E2=80=98thresholds->primary =3D NULL=E2=80= =98 =EF=BC=9F 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 =3D NULL; + } + rcu_assign_pointer(thresholds->primary, new);<---------*HERE* /* To be sure that nobody uses thresholds */ From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx113.postini.com [74.125.245.113]) by kanga.kvack.org (Postfix) with SMTP id 8E7946B0083 for ; Thu, 8 Mar 2012 23:35:48 -0500 (EST) Received: by dadv6 with SMTP id v6so1240256dad.14 for ; Thu, 08 Mar 2012 20:35:47 -0800 (PST) Message-ID: <4F598204.9030504@gmail.com> Date: Fri, 09 Mar 2012 12:07:32 +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> <20120309124021.810f5267.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20120309124021.810f5267.kamezawa.hiroyu@jp.fujitsu.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org List-ID: To: KAMEZAWA Hiroyuki Cc: linux-mm@kvack.org, cgroups@vger.kernel.org, kirill@shutemov.name, Sha Zhengju 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 a??thresholds->primary = NULLa?? i 1/4 ? 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* /* To be sure that nobody uses thresholds */ -- 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