linux-kernel - Re: [PATCH] MAINTAINERS: add mm THP section

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Message-ID: <aAp7ggknCytUyAXd@casper.infradead.org>
Date: Thu, 24 Apr 2025 18:57:22 +0100
From: Matthew Wilcox <willy@...radead.org>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	David Hildenbrand <david@...hat.com>, Zi Yan <ziy@...dia.com>,
	Baolin Wang <baolin.wang@...ux.alibaba.com>,
	"Liam R . Howlett" <Liam.Howlett@...cle.com>,
	Nico Pache <npache@...hat.com>, Ryan Roberts <ryan.roberts@....com>,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] MAINTAINERS: add mm THP section

On Thu, Apr 24, 2025 at 12:16:32PM +0100, Lorenzo Stoakes wrote:
> As part of the ongoing efforts to sub-divide memory management
> maintainership and reviewership, establish a section for Transparent Huge
> Page support and add appropriate maintainers and reviewers.

I'm quite queasy about this.  I'm doing my best to make "THP" disappear
as a concept.  How would you define what THP is?  Originally, it was
PMD-sized-and-aligned allocations, and some of the way we expose it to
userspace, that's still the interpretation.  But we also have folios which
are of some hardware-defined magic sizes, as well as (for filesystems,
at least) random other non-zero orders.

Memory is just managed in variously sized quantities.  There should be
nothing magic about "THP", and I'm still annoyed at the anon-mem people
for baking various magic sizes into user-visible APIs.