linux-kernel - Re: [RFC PATCH 0/3] hugetlb: add demote/split page functionality

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Message-ID: <dfd59d83-7916-518d-23ce-a9a4e6781918@redhat.com>
Date:   Tue, 9 Mar 2021 20:01:29 +0100
From:   David Hildenbrand <david@...hat.com>
To:     Mike Kravetz <mike.kravetz@...cle.com>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Cc:     Michal Hocko <mhocko@...e.com>, Oscar Salvador <osalvador@...e.de>,
        Zi Yan <ziy@...dia.com>, David Rientjes <rientjes@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [RFC PATCH 0/3] hugetlb: add demote/split page functionality

> I need to take a close look at Oscar's patches.  Too many thing to look
> at/review :)
> 
> This series does take into account gigantic pages allocated in CMA.
> Such pages can be demoted, and we need to track that they need to go
> back to CMA.  Nothing super special for this, mostly a new hugetlb
> specific flag to track such pages.

Ah, just spotted it - patch #2 :)

Took me a while to figure out that we end up calling 
cma_declare_contiguous_nid() with order_per_bit=0 - would have thought 
we would be using the actual smallest allocation order we end up using 
for huge/gigantic pages via CMA. Well, this way it "simply works".

-- 
Thanks,

David / dhildenb