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Message-ID: <55345756.40902@huawei.com>
Date: Mon, 20 Apr 2015 09:33:10 +0800
From: Xishi Qiu <qiuxishi@huawei.com>
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To: Yasuaki Ishimatsu <yasu.isimatu@gmail.com>
CC: Andrew Morton <akpm@linux-foundation.org>,
        Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>,
        Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        <izumi.taku@jp.fujitsu.com>, Tang Chen <tangchen@cn.fujitsu.com>,
        Gu Zheng <guz.fnst@cn.fujitsu.com>, Xiexiuqi <xiexiuqi@huawei.com>,
        Mel Gorman <mgorman@suse.de>, David Rientjes <rientjes@google.com>,
        Linux MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>,
        <yasu.ishimatsu@gmail.com>
Subject: Re: [PATCH 1/2 V2] memory-hotplug: fix BUG_ON in move_freepages()
References: <5530E578.9070505@huawei.com> <5531679d.4642ec0a.1beb.3569@mx.google.com>
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On 2015/4/18 4:05, Yasuaki Ishimatsu wrote:

> 
> Your patches will fix your issue.
> But, if BIOS reports memory first at node hot add, pgdat can
> not be initialized.
> 
> Memory hot add flows are as follows:
> 
> add_memory
>   ...
>   -> hotadd_new_pgdat()
>   ...
>   -> node_set_online(nid)
> 
> When calling hotadd_new_pgdat() for a hot added node, the node is
> offline because node_set_online() is not called yet. So if applying
> your patches, the pgdat is not initialized in this case.
> 
> Thanks,
> Yasuaki Ishimatsu
> 

Hi Yasuaki,

I'm not quite understand, when BIOS reports memory first, why pgdat
can not be initialized?
When hotadd a new node, hotadd_new_pgdat() will be called too, and
when hotadd memory to a existent node, it's no need to call hotadd_new_pgdat(),
right?

Thanks,
Xishi Qiu

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