From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1752025AbbJNDhX (ORCPT <rfc822;w@1wt.eu>);
	Tue, 13 Oct 2015 23:37:23 -0400
Received: from szxga03-in.huawei.com ([119.145.14.66]:43348 "EHLO
	szxga03-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1750995AbbJNDhQ (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Tue, 13 Oct 2015 23:37:16 -0400
Message-ID: <561DCBF9.4050000@huawei.com>
Date: Wed, 14 Oct 2015 11:28:57 +0800
From: Xishi Qiu <qiuxishi@huawei.com>
User-Agent: Mozilla/5.0 (Windows NT 6.1; rv:12.0) Gecko/20120428 Thunderbird/12.0.1
MIME-Version: 1.0
To: Tang Chen <tangchen@cn.fujitsu.com>
CC: Yasuaki Ishimatsu <yasu.isimatu@gmail.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>,
        Mel Gorman <mgorman@suse.de>, "David Rientjes" <rientjes@google.com>,
        <zhongjiang@huawei.com>, Linux MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: skip if required_kernelcore is larger than totalpages
References: <5615D311.5030908@huawei.com> <5617e00e.0c5b8c0a.2d0dd.3faa@mx.google.com> <561B0ECD.5000507@huawei.com> <561DC30C.70909@cn.fujitsu.com>
In-Reply-To: <561DC30C.70909@cn.fujitsu.com>
Content-Type: text/plain; charset="ISO-8859-1"
Content-Transfer-Encoding: 7bit
X-Originating-IP: [10.177.25.179]
X-CFilter-Loop: Reflected
X-Mirapoint-Virus-RAPID-Raw: score=unknown(0),
	refid=str=0001.0A020205.561DCC06.00E8,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0,
	ip=0.0.0.0,
	so=2013-05-26 15:14:31,
	dmn=2013-03-21 17:37:32
X-Mirapoint-Loop-Id: 7029c9513422f257f084df9fc572f07c
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On 2015/10/14 10:50, Tang Chen wrote:

> Hi, Qiu
> 
> The patch seems OK to me. Only one little concern below.
> 
> On 10/12/2015 09:37 AM, Xishi Qiu wrote:
>> On 2015/10/9 23:41, Yasuaki Ishimatsu wrote:
>>
>>> On Thu, 8 Oct 2015 10:21:05 +0800
>>> Xishi Qiu <qiuxishi@huawei.com> wrote:
>>>
>>>> If kernelcore was not specified, or the kernelcore size is zero
>>>> (required_movablecore >= totalpages), or the kernelcore size is larger
>>> Why does required_movablecore become larger than totalpages, when the
>>> kernelcore size is zero? I read the code but I could not find that you
>>> mention.
>>>
>> If user only set boot option movablecore, and the value is larger than
>> totalpages, the calculation of kernelcore is zero, but we can't fill
>> the zone only with kernelcore, so skip it.
>>
>> I have send a patch before this patch.
>> "fix overflow in find_zone_movable_pfns_for_nodes()"
>>         ...
>>           required_movablecore =
>>               roundup(required_movablecore, MAX_ORDER_NR_PAGES);
>> +        required_movablecore = min(totalpages, required_movablecore);
>>           corepages = totalpages - required_movablecore;
>>         ...
> 
> 
> So if required_movablecore >= totalpages, there won't be any ZONE_MOVABLE.
> How about add a warning or debug info to tell the user he has specified a
> too large movablecore, and it is ignored ?
> 
> Thanks.

Yes, but I don't think is is necessary, user should know the total memory
before he set the boot option.

Thanks,
Xishi Qiu