linux-kernel - Re: [RFC PATCH] mm,memory_hotplug: Unlock 1GB-hugetlb on x86

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Date:   Thu, 28 Feb 2019 11:19:52 +0100
From:   Oscar Salvador <osalvador@...e.de>
To:     Michal Hocko <mhocko@...nel.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org, david@...hat.com,
        mike.kravetz@...cle.com
Subject: Re: [RFC PATCH] mm,memory_hotplug: Unlock 1GB-hugetlb on x86_64

On Thu, Feb 28, 2019 at 10:55:35AM +0100, Michal Hocko wrote:
> You seemed to miss my point or I am wrong here. If scan_movable_pages
> skips over a hugetlb page then there is nothing to migrate it and it
> will stay in the pfn range and the range will not become idle.

I might be misunterstanding you, but I am not sure I get you.

scan_movable_pages() can either skip or not a hugetlb page.
In case it does, pfn will be incremented to skip the whole hugetlb
range.
If that happens, pfn will hold the next non-hugetlb page.

If it happens that the end of the hugetlb page is also the end
of the memory range, scan_movable_pages() will return 0 and we will
eventually break the loop in __offline_pages().

If this is not what you meant, could you please elaborate a bit more your concern?

-- 
Oscar Salvador
SUSE L3