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Subject: Re: [PATCH RFC 0/1] mm: balancing the node zones occupancy
To:     Charan Teja Reddy <charante@codeaurora.org>,
        akpm@linux-foundation.org, rientjes@google.com, vbabka@suse.cz,
        mhocko@suse.com, mgorman@techsingularity.net, linux-mm@kvack.org
Cc:     vinmenon@codeaurora.org, sudaraja@codeaurora.org,
        linux-kernel@vger.kernel.org
References: <cover.1613661472.git.charante@codeaurora.org>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat GmbH
Message-ID: <82e0e9c2-8187-8e2f-0d5e-304dafcda017@redhat.com>
Date:   Thu, 18 Feb 2021 19:16:30 +0100
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On 18.02.21 18:24, Charan Teja Reddy wrote:
> I would like to start discussion about  balancing the occupancy of
> memory zones in a node in the system whose imabalance may be caused by
> migration of pages to other zones during hotremove and then hotadding
> same memory. In this case there is a lot of free memory in newly hotadd
> memory which can be filled up by the previous migrated pages(as part of
> offline/hotremove) thus may free up some pressure in other zones of the
> node.

Why is this specific to memory hot(un)plug? I think the problem is more 
generic:

Assume

1. Application 1 allocates a lot of memory and gets ZONE_MOVABLE.
2. Application 2 allocates a lot of memory and gets ZONE_NORMAL.
3. Application 1 quits.

Same problem, no?

-- 
Thanks,

David / dhildenb