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Date:   Wed, 18 Mar 2020 18:57:07 +0000 (UTC)
From:   Christopher Lameter <cl@linux.com>
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To:     Michal Hocko <mhocko@kernel.org>
cc:     Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
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        linux-kernel@vger.kernel.org, Mel Gorman <mgorman@suse.de>,
        Vlastimil Babka <vbabka@suse.cz>,
        "Kirill A. Shutemov" <kirill@shutemov.name>,
        Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 3/3] mm/page_alloc: Keep memoryless cpuless node 0
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On Mon, 16 Mar 2020, Michal Hocko wrote:

> > We can dynamically number the nodes right? So just make sure that the
> > firmware properly creates memory on node 0?
>
> Are you suggesting that the OS would renumber NUMA nodes coming
> from FW just to satisfy node 0 existence? If yes then I believe this is
> really a bad idea because it would make HW/LPAR configuration matching
> to the resulting memory layout really hard to follow.

NUMA nodes are created by the OS based on information provided by the
firmware. Either the FW would need to ensure that a viable node 0 exists
or the bootstrap arch code could setup things to the same effect.