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

Ard Biesheuvel
2026-01-23T06:44:38Z

On Fri, 23 Jan 2026 at 07:43, Anshuman Khandual
<anshuman.khandual@arm.com> wrote:
>
>
>
> 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.
>

It is related to the other three patches: the 4th patch requires it.

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

Thanks!