linux-kernel - Re: powerpc,numa: Memory hotplug to memory-less nodes ?

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Message-ID: <20160511215051.GF22115@arbab-laptop.austin.ibm.com>
Date:	Wed, 11 May 2016 16:50:51 -0500
From:	Reza Arbab <arbab@...ux.vnet.ibm.com>
To:	Bharata B Rao <bharata.rao@...il.com>,
	Nathan Fontenot <nfont@...ux.vnet.ibm.com>,
	Anshuman Khandual <khandual@...ux.vnet.ibm.com>
Cc:	linuxppc-dev@...ts.ozlabs.org, linux-kernel@...r.kernel.org
Subject: Re: powerpc,numa: Memory hotplug to memory-less nodes ?

On Mon, Jun 22, 2015 at 10:18:43AM +0530, Bharata B Rao wrote:
>While developing memory hotplug support in QEMU for PoweKVM, I
>realized that guest kernel has specific checks to prevent hot addition
>of memory to a memory-less node.
>
>I am referring to arch/powerpc/mm/numa.c:hot_add_scn_to_nid() which
>has explicit checks to ensure that it returns a nid that has some some
>memory (NODE_DATA(nid)->node_spanned_pages) even when user wants to
>hotplug to a node that currently has zero memory.
>
>Is this limitation by design ?

Sorry to resurrect such an old thread, but did anything come of this?

I've recently bumped into the same limitation. Could we consider 
removing it?

(I couldn't find the original distribution list for this thread. Please 
add whomever is appropriate to the Cc:)

-- 
Reza Arbab