From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753286Ab3AGBav (ORCPT ); Sun, 6 Jan 2013 20:30:51 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:64996 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752664Ab3AGBas (ORCPT ); Sun, 6 Jan 2013 20:30:48 -0500 X-IronPort-AV: E=Sophos;i="4.84,421,1355068800"; d="scan'208";a="6532369" Message-ID: <50EA2511.3070009@cn.fujitsu.com> Date: Mon, 07 Jan 2013 09:29:53 +0800 From: Lin Feng User-Agent: Mozilla/5.0 (X11; Linux i686; rv:15.0) Gecko/20120911 Thunderbird/15.0.1 MIME-Version: 1.0 To: Tejun Heo CC: akpm@linux-foundation.org, mingo@kernel.org, yinghai@kernel.org, liwanp@linux.vnet.ibm.com, benh@kernel.crashing.org, tangchen@cn.fujitsu.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH] mm: memblock: fix wrong memmove size in memblock_merge_regions() References: <1357290650-25544-1-git-send-email-linfeng@cn.fujitsu.com> <20130104145635.GA15633@mtj.dyndns.org> In-Reply-To: <20130104145635.GA15633@mtj.dyndns.org> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2013/01/07 09:30:16, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2013/01/07 09:30:17, Serialize complete at 2013/01/07 09:30:17 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/04/2013 10:56 PM, Tejun Heo wrote: > On Fri, Jan 04, 2013 at 05:10:50PM +0800, Lin Feng wrote: >> The memmove span covers from (next+1) to the end of the array, and the index >> of next is (i+1), so the index of (next+1) is (i+2). So the size of remaining >> array elements is (type->cnt - (i + 2)). >> >> PS. It seems that memblock_merge_regions() could be made some improvement: >> we need't memmove the remaining array elements until we find a none-mergable >> element, but now we memmove everytime we find a neighboring compatible region. >> I'm not sure if the trial is worth though. >> >> Cc: Tejun Heo >> Signed-off-by: Lin Feng >> --- >> mm/memblock.c | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/mm/memblock.c b/mm/memblock.c >> index 6259055..85ce056 100644 >> --- a/mm/memblock.c >> +++ b/mm/memblock.c >> @@ -314,7 +314,7 @@ static void __init_memblock memblock_merge_regions(struct memblock_type *type) >> } >> >> this->size += next->size; >> - memmove(next, next + 1, (type->cnt - (i + 1)) * sizeof(*next)); >> + memmove(next, next + 1, (type->cnt - (i + 2)) * sizeof(*next)); > > Heh, that's confusing. Nice catch. Can you please also add a comment > explaning the index so that it's less confusing for the future readers? Hi Tejun, Glad to. I will resend it soon. thanks, linfeng > > Thanks. >