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Date:   Thu, 6 Aug 2020 21:32:11 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc:     Michal Hocko <mhocko@kernel.org>,
        Michal Such?nek <msuchanek@suse.de>,
        David Hildenbrand <david@redhat.com>,
        Gautham R Shenoy <ego@linux.vnet.ibm.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        Satheesh Rajendran <sathnaga@linux.vnet.ibm.com>,
        Mel Gorman <mgorman@suse.de>,
        "Kirill A. Shutemov" <kirill@shutemov.name>,
        linuxppc-dev@lists.ozlabs.org, Christopher Lameter <cl@linux.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Andi Kleen <ak@linux.intel.com>
Subject: Re: [PATCH v5 3/3] mm/page_alloc: Keep memoryless cpuless node 0
 offline
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On Fri, 3 Jul 2020 18:28:23 +0530 Srikar Dronamraju <srikar@linux.vnet.ibm.com> wrote:

> > The memory hotplug changes that somehow because you can hotremove numa
> > nodes and therefore make the nodemask sparse but that is not a common
> > case. I am not sure what would happen if a completely new node was added
> > and its corresponding node was already used by the renumbered one
> > though. It would likely conflate the two I am afraid. But I am not sure
> > this is really possible with x86 and a lack of a bug report would
> > suggest that nobody is doing that at least.
> > 
> 
> JFYI,
> Satheesh copied in this mailchain had opened a bug a year on crash with vcpu
> hotplug on memoryless node. 
> 
> https://bugzilla.kernel.org/show_bug.cgi?id=202187

So...  do we merge this patch or not?  Seems that the overall view is
"risky but nobody is likely to do anything better any time soon"?