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Reply-To: "Hillf Danton" <hillf.zj@alibaba-inc.com>
From: "Hillf Danton" <hillf.zj@alibaba-inc.com>
To: "'Michal Hocko'" <mhocko@kernel.org>, <linux-mm@kvack.org>
Cc: "'Andrew Morton'" <akpm@linux-foundation.org>,
        "'Mel Gorman'" <mgorman@suse.de>, "'Vlastimil Babka'" <vbabka@suse.cz>,
        "'Andrea Arcangeli'" <aarcange@redhat.com>,
        "'Reza Arbab'" <arbab@linux.vnet.ibm.com>,
        "'Yasuaki Ishimatsu'" <yasu.isimatu@gmail.com>,
        "'Tang Chen'" <tangchen@cn.fujitsu.com>, <qiuxishi@huawei.com>,
        "'Kani Toshimitsu'" <toshi.kani@hpe.com>, <slaoub@gmail.com>,
        "'Joonsoo Kim'" <js1304@gmail.com>,
        "'Andi Kleen'" <ak@linux.intel.com>,
        "'David Rientjes'" <rientjes@google.com>,
        "'Daniel Kiper'" <daniel.kiper@oracle.com>,
        "'Igor Mammedov'" <imammedo@redhat.com>,
        "'Vitaly Kuznetsov'" <vkuznets@redhat.com>,
        "'LKML'" <linux-kernel@vger.kernel.org>,
        "'Michal Hocko'" <mhocko@suse.com>,
        "'Dan Williams'" <dan.j.williams@gmail.com>,
        "'Heiko Carstens'" <heiko.carstens@de.ibm.com>,
        "'Lai Jiangshan'" <laijs@cn.fujitsu.com>,
        "'Martin Schwidefsky'" <schwidefsky@de.ibm.com>
References: <20170330115454.32154-1-mhocko@kernel.org> <20170330115454.32154-6-mhocko@kernel.org>
In-Reply-To: <20170330115454.32154-6-mhocko@kernel.org>
Subject: Re: [PATCH 5/6] mm, memory_hotplug: do not associate hotadded memory to zones until online
Date: Fri, 31 Mar 2017 14:18:08 +0800
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On March 30, 2017 7:55 PM Michal Hocko wrote:
> 
> +static void __meminit resize_zone_range(struct zone *zone, unsigned long start_pfn,
> +		unsigned long nr_pages)
> +{
> +	unsigned long old_end_pfn = zone_end_pfn(zone);
> +
> +	if (start_pfn < zone->zone_start_pfn)
> +		zone->zone_start_pfn = start_pfn;
> +
> +	zone->spanned_pages = max(start_pfn + nr_pages, old_end_pfn) - zone->zone_start_pfn;
> +}
The implementation above implies zone can only go bigger.
Can we resize zone with the given data?

btw,  this mail address, Zhang Zhen <zhenzhang.zhang@huawei.com> , is not reachable. 

Hillf