Re: [PATCH v2 4/4] mm: cache struct page for empty_zero_page and return it from ZERO_PAGE()

From: Catalin Marinas <catalin.marinas@arm.com>
To: Mike Rapoport <rppt@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Andreas Larsson <andreas@gaisler.com>,
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Subject: Re: [PATCH v2 4/4] mm: cache struct page for empty_zero_page and return it from ZERO_PAGE()
Date: Tue, 10 Feb 2026 15:06:51 +0000	[thread overview]
Message-ID: <aYtJi4uNcpoCTK_x@arm.com> (raw)
In-Reply-To: <20260209144058.2092871-5-rppt@kernel.org>

On Mon, Feb 09, 2026 at 04:40:57PM +0200, 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().
> 
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

For arm64:

Acked-by: Catalin Marinas <catalin.marinas@arm.com>