linux-kernel - Re: [PATCH] docs: update THP documentation to clarify sysfs "never" setting

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Message-ID: <E48F7A00-D103-4C5D-901D-44085E92AB7A@nvidia.com>
Date: Mon, 21 Jul 2025 21:13:21 -0400
From: Zi Yan <ziy@...dia.com>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
 David Hildenbrand <david@...hat.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>, Dev Jain <dev.jain@....com>,
 Barry Song <baohua@...nel.org>, Jonathan Corbet <corbet@....net>,
 linux-mm@...ck.org, linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] docs: update THP documentation to clarify sysfs "never"
 setting

On 21 Jul 2025, at 11:55, Lorenzo Stoakes wrote:

> Rather confusingly, setting all Transparent Huge Page sysfs settings to
> "never" does not in fact result in THP being globally disabled.
>
> Rather, it results in khugepaged being disabled, but one can still obtain
> THP pages using madvise(..., MADV_COLLAPSE).
>
> This is something that has remained poorly documented for some time, and it
> is likely the received wisdom of most users of THP that never does, in
> fact, mean never.
>
> It is therefore important to highlight, very clearly, that this is not the
> ase.
>
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> ---
>  Documentation/admin-guide/mm/transhuge.rst | 11 +++++++++--
>  1 file changed, 9 insertions(+), 2 deletions(-)
>

LGTM. Reviewed-by: Zi Yan <ziy@...dia.com>

Best Regards,
Yan, Zi