Re: [PATCH v3 4/4] mm: cache struct page for empty_zero_page and return it from ZERO_PAGE()

From: "David Hildenbrand (Arm)" <david@kernel.org>
To: Mike Rapoport <rppt@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: Andreas Larsson <andreas@gaisler.com>,
	Borislav Petkov <bp@alien8.de>, Brian Cain <bcain@kernel.org>,
	Catalin Marinas <catalin.marinas@arm.com>,
	"Christophe Leroy (CS GROUP)" <chleroy@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	Dinh Nguyen <dinguyen@kernel.org>,
	Geert Uytterhoeven <geert@linux-m68k.org>,
	Guo Ren <guoren@kernel.org>, Helge Deller <deller@gmx.de>,
	Huacai Chen <chenhuacai@kernel.org>,
	Ingo Molnar <mingo@redhat.com>,
	Johannes Berg <johannes@sipsolutions.net>,
	John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
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	Lorenzo Stoakes <lorenzo.stoakes@oracle.com>,
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Subject: Re: [PATCH v3 4/4] mm: cache struct page for empty_zero_page and return it from ZERO_PAGE()
Date: Thu, 12 Feb 2026 10:08:49 +0100	[thread overview]
Message-ID: <612ea310-699a-4fa4-b007-5b4ab5019eda@kernel.org> (raw)
In-Reply-To: <20260211103141.3215197-5-rppt@kernel.org>

On 2/11/26 11:31, Mike Rapoport wrote:
> From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>
> 
> For most architectures every invocation of ZERO_PAGE() does
> virt_to_page(empty_zero_page). But empty_zero_page is in BSS and it is
> enough to get its struct page once at initialization time and then use
> it whenever a zero page should be accessed.
> 
> Add yet another __zero_page variable that will be initialized as
> virt_to_page(empty_zero_page) for most architectures in a weak
> arch_setup_zero_pages() function.
> 
> For architectures that use colored zero pages (MIPS and s390) rename their
> setup_zero_pages() to arch_setup_zero_pages() and make it global rather
> than static.
> 
> For architectures that cannot use virt_to_page() for BSS (arm64 and
> sparc64) add override of arch_setup_zero_pages().
> 
> Acked-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
> ---

Acked-by: David Hildenbrand (Arm) <david@kernel.org>

-- 
Cheers,

David