Re: [PATCH 3/4] arm64: Move the zero page to rodata

Anshuman Khandual
2026-01-23T06:43:29Z

On 19/01/26 10:17 PM, Ard Biesheuvel wrote:
> From: Ard Biesheuvel <ardb@kernel.org>
>
> The zero page should contain only zero bytes, and so mapping it
> read-write is unnecessary. Move it to __ro_after_init instead.
>
> Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> ---
> arch/arm64/mm/mmu.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 2a18637ecc15..d978b07ab7b8 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -68,7 +68,8 @@ long __section(".mmuoff.data.write") __early_cpu_boot_status;
> * Empty_zero_page is a special page that is used for zero-initialized data
> * and COW.
> */
> -unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)] __page_aligned_bss;
> +unsigned long empty_zero_page[PAGE_SIZE / sizeof(unsigned long)]
> + __ro_after_init __aligned(PAGE_SIZE);
> EXPORT_SYMBOL(empty_zero_page);
>
> static DEFINE_SPINLOCK(swapper_pgdir_lock);

A small nit - could this be the first patch in the series here ? Becasue it is
not related to other three patches.

Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>