From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751862Ab2GDMce (ORCPT ); Wed, 4 Jul 2012 08:32:34 -0400 Received: from mx2.parallels.com ([64.131.90.16]:33865 "EHLO mx2.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751095Ab2GDMcc (ORCPT ); Wed, 4 Jul 2012 08:32:32 -0400 Message-ID: <4FF4373C.8020100@parallels.com> Date: Wed, 4 Jul 2012 16:29:48 +0400 From: Glauber Costa User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:13.0) Gecko/20120615 Thunderbird/13.0.1 MIME-Version: 1.0 To: Wanpeng Li CC: Johannes Weiner , Michal Hocko , Balbir Singh , AndrewMorton , Eric Dumazet , Mike Frysinger , Arun Sharma , , Subject: Re: [PATCH 1/5 v2] memcg: replace unsigned long by u64 to avoid overflow References: <1340604266-7937-1-git-send-email-liwp.linux@gmail.com> <20120625075215.GW27816@cmpxchg.org> <4FE82193.1070307@jp.fujitsu.com> <20120704122427.GA21598@kernel> In-Reply-To: <20120704122427.GA21598@kernel> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 07/04/2012 04:24 PM, Wanpeng Li wrote: > On Mon, Jun 25, 2012 at 05:30:11PM +0900, Kamezawa Hiroyuki wrote: >> (2012/06/25 16:52), Johannes Weiner wrote: >>> On Mon, Jun 25, 2012 at 02:04:20PM +0800, Wanpeng Li wrote: >>>> Changlog: >>>> >>>> V2 -> V1: >>>> * fix zone_page_state()::/include/linux/vmstat.h returns 'unsigned long' >>>> >>>> From: Wanpeng Li >>>> >>>> Since the return value variable in mem_cgroup_zone_nr_lru_pages and >>>> mem_cgroup_node_nr_lru_pages functions are u64, so replace the return >>>> value of funtions by u64 to avoid overflow. >>>> >>>> Signed-off-by: Wanpeng Li >>>> --- >>>> include/linux/vmstat.h | 2 +- >>>> mm/memcontrol.c | 5 ++--- >>>> 2 files changed, 3 insertions(+), 4 deletions(-) >>>> >>>> diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h >>>> index 65efb92..6a14291 100644 >>>> --- a/include/linux/vmstat.h >>>> +++ b/include/linux/vmstat.h >>>> @@ -106,7 +106,7 @@ static inline unsigned long global_page_state(enum zone_stat_item item) >>>> return x; >>>> } >>>> >>>> -static inline unsigned long zone_page_state(struct zone *zone, >>>> +static inline u64 zone_page_state(struct zone *zone, >>>> enum zone_stat_item item) >>>> { >>>> long x = atomic_long_read(&zone->vm_stat[item]); >>> >>> We established that there is no known reason to use ulong for page >>> counters and that IF YOU HAD ONE, you should obviously say so and then >>> do a wholesale conversion. But I don't think you have one. >>> >>> This patch makes absolutely no sense. >>> >> I agree. Then, Nack from me. >> >> Thanks, >> -Kame > > static unsigned long > mem_cgroup_node_nr_lru_pages(struct mem_cgroup *memcg, > int nid, unsigned int lru_mask) > { > u64 total = 0; > int zid; > > for (zid = 0; zid < MAX_NR_ZONES; zid++) > total += mem_cgroup_zone_nr_lru_pages(memcg, > nid, zid, lru_mask); > > return total; > } > > Since you use unsigned long to caculate nr_pages and unsigned long long > to caculate bytes, so u64 in function mem_cgroup_node_nr_lru_pages should > replace by unsigned long to save kernel stack, right? How many bytes do you intend to save by replacing "u64" with "unsigned long" ? Have you asked yourself this question ?