linux-kernel - Re: [PATCH v8 2/7] mm: introduce clear_pages() and clear_user

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Message-ID: <11e86b31-fd8f-44ab-906e-019fde89215c@kernel.org>
Date: Tue, 18 Nov 2025 08:34:15 +0100
From: "David Hildenbrand (Red Hat)" <david@...nel.org>
To: Ankur Arora <ankur.a.arora@...cle.com>, linux-kernel@...r.kernel.org,
 linux-mm@...ck.org, x86@...nel.org
Cc: akpm@...ux-foundation.org, bp@...en8.de, dave.hansen@...ux.intel.com,
 hpa@...or.com, mingo@...hat.com, mjguzik@...il.com, luto@...nel.org,
 peterz@...radead.org, acme@...nel.org, namhyung@...nel.org,
 tglx@...utronix.de, willy@...radead.org, raghavendra.kt@....com,
 boris.ostrovsky@...cle.com, konrad.wilk@...cle.com
Subject: Re: [PATCH v8 2/7] mm: introduce clear_pages() and clear_user_pages()

On 27.10.25 21:21, Ankur Arora wrote:
> Introduce clear_pages(), to be overridden by architectures that
> support more efficient clearing of consecutive pages.
> 
> Also introduce clear_user_pages(), however, we will not expect
> this function to be overridden anytime soon.
> 
> We have to place the clear_user_pages() variant that uses
> clear_user_page() into mm/util.c for now to work around
> macro magic on sparc and m68k.
> 
> Signed-off-by: Ankur Arora <ankur.a.arora@...cle.com>
> ---
>   include/linux/mm.h | 41 +++++++++++++++++++++++++++++++++++++++++
>   mm/util.c          | 13 +++++++++++++
>   2 files changed, 54 insertions(+)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 683168b522b3..ecbcb76df9de 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -3872,6 +3872,26 @@ static inline void clear_page_guard(struct zone *zone, struct page *page,
>   				unsigned int order) {}
>   #endif	/* CONFIG_DEBUG_PAGEALLOC */
>   
> +#ifndef __HAVE_ARCH_CLEAR_PAGES

Also here, let's base it on

#ifndef clear_pages

and similarly below for clear_user_pages.

(sorry for the back-and-forth, it's rather unclear what the best 
practice is)

-- 
Cheers

David