From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx205.postini.com [74.125.245.205]) by kanga.kvack.org (Postfix) with SMTP id 08DA86B005D for ; Fri, 4 Jan 2013 09:56:39 -0500 (EST) Received: by mail-qc0-f174.google.com with SMTP id o22so8726508qcr.19 for ; Fri, 04 Jan 2013 06:56:39 -0800 (PST) Date: Fri, 4 Jan 2013 09:56:35 -0500 From: Tejun Heo Subject: Re: [RFC PATCH] mm: memblock: fix wrong memmove size in memblock_merge_regions() Message-ID: <20130104145635.GA15633@mtj.dyndns.org> References: <1357290650-25544-1-git-send-email-linfeng@cn.fujitsu.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1357290650-25544-1-git-send-email-linfeng@cn.fujitsu.com> Sender: owner-linux-mm@kvack.org List-ID: To: Lin Feng 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 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? Thanks. -- tejun -- 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/ . Don't email: email@kvack.org