linux-kernel - Re: [PATCH mm-new 1/3] mm/khugepaged: skip unsuitable VMAs earlier in khugepaged_scan_mm

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Message-ID: <bc86d5f7-5b23-14fb-0365-b47f5a6f13c9@google.com>
Date: Mon, 15 Sep 2025 22:32:14 -0700 (PDT)
From: Hugh Dickins <hughd@...gle.com>
To: Lance Yang <lance.yang@...ux.dev>
cc: akpm@...ux-foundation.org, david@...hat.com, lorenzo.stoakes@...cle.com, 
    ziy@...dia.com, baolin.wang@...ux.alibaba.com, Liam.Howlett@...cle.com, 
    npache@...hat.com, ryan.roberts@....com, dev.jain@....com, 
    baohua@...nel.org, ioworker0@...il.com, linux-kernel@...r.kernel.org, 
    linux-mm@...ck.org
Subject: Re: [PATCH mm-new 1/3] mm/khugepaged: skip unsuitable VMAs earlier
 in khugepaged_scan_mm_slot()

On Sun, 14 Sep 2025, Lance Yang wrote:

> From: Lance Yang <lance.yang@...ux.dev>
> 
> Let's skip unsuitable VMAs early in the khugepaged scan; specifically,
> mlocked VMAs should not be touched.

Why?  That's a change in behaviour, isn't it?

I'm aware that hugepage collapse on an mlocked VMA can insert a fault
latency, not universally welcome; but I've not seen discussion, let
alone agreement, that current behaviour should be changed.
Somewhere in yet-to-be-read mail?  Please give us a link.

Hugh