Date: Thu, 1 Jun 2017 10:47:46 -0500
From: Reza Arbab <arbab@linux.vnet.ibm.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>, linux-mm@kvack.org,
        Andrew Morton <akpm@linux-foundation.org>,
        Mel Gorman <mgorman@suse.de>, Andrea Arcangeli <aarcange@redhat.com>,
        Jerome Glisse <jglisse@redhat.com>,
        Yasuaki Ishimatsu <yasu.isimatu@gmail.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>
Subject: Re: [RFC PATCH] mm, memory_hotplug: support movable_node for
 hotplugable nodes
References: <20170601122004.32732-1-mhocko@kernel.org>
 <820164f3-8bef-7761-0695-88db9e0ce7a7@suse.cz>
 <20170601142227.GF9091@dhcp22.suse.cz>
 <20170601151935.m5jbfmugocc66qfq@arbab-laptop.localdomain>
 <20170601153838.GA8088@dhcp22.suse.cz>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii; format=flowed
Content-Disposition: inline
In-Reply-To: <20170601153838.GA8088@dhcp22.suse.cz>
Organization: IBM Linux Technology Center
User-Agent: NeoMutt/20170428 (1.8.2)
Message-Id: <20170601154746.wjc56eldgyzr2bpm@arbab-laptop.localdomain>
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 929
Lines: 24

On Thu, Jun 01, 2017 at 05:38:38PM +0200, Michal Hocko wrote:
>On Thu 01-06-17 10:19:36, Reza Arbab wrote:
>> The x86 SRAT (or the dt, on other platforms) can describe memory as
>> hotpluggable. See memblock_mark_hotplug(). That's only for memory present at
>> boot, though.
>
>Yes but lose that information after the memblock is gone and numa fully
>initialized. Or can we reconstruct that somehow?

I'm not sure you'd have to. At boot time, those markings are used to 
determine the initial boundaries of ZONE_MOVABLE. So if you removed 
these memblocks, then readded them, they would still be in ZONE_MOVABLE.

>> He's saying that since the memory was added after boot, it is by 
>> definition hotpluggable. There's no need to check for that 
>> marking/description.
>
>Yes, but we do not know whether we are onlining memblocks from a boot
>time numa node or a fresh one which has been hotadded.

That's true.

-- 
Reza Arbab