linux-kernel - Re: [PATCH 07/13] s390: make setup_zero

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Message-ID: <CAMj1kXHS1YbnYVqVgsyfFSpg9kJM599Yp9TO8AP6--Nbgk7dHQ@mail.gmail.com>
Date: Wed, 12 Mar 2025 16:56:59 +0100
From: Ard Biesheuvel <ardb@...nel.org>
To: Mike Rapoport <rppt@...nel.org>
Cc: Heiko Carstens <hca@...ux.ibm.com>, Andrew Morton <akpm@...ux-foundation.org>, 
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Subject: Re: [PATCH 07/13] s390: make setup_zero_pages() use memblock

On Tue, 11 Mar 2025 at 06:56, Mike Rapoport <rppt@...nel.org> wrote:
>
> On Fri, Mar 07, 2025 at 04:28:15PM +0100, Heiko Carstens wrote:
> > On Thu, Mar 06, 2025 at 08:51:17PM +0200, Mike Rapoport wrote:
> > > From: "Mike Rapoport (Microsoft)" <rppt@...nel.org>
> > >
> > > Allocating the zero pages from memblock is simpler because the memory is
> > > already reserved.
> > >
> > > This will also help with pulling out memblock_free_all() to the generic
> > > code and reducing code duplication in arch::mem_init().
> > >
> > > Signed-off-by: Mike Rapoport (Microsoft) <rppt@...nel.org>
> > > ---
> > >  arch/s390/mm/init.c | 14 +++-----------
> > >  1 file changed, 3 insertions(+), 11 deletions(-)
> >
> > Acked-by: Heiko Carstens <hca@...ux.ibm.com>
> >
> > > -   empty_zero_page = __get_free_pages(GFP_KERNEL | __GFP_ZERO, order);
> > > +   empty_zero_page = (unsigned long)memblock_alloc(PAGE_SIZE << order, order);
> > >     if (!empty_zero_page)
> > >             panic("Out of memory in setup_zero_pages");
> >
> > This could have been converted to memblock_alloc_or_panic(), but I
> > guess this can also be done at a later point in time.
>
> Duh, I should have remembered about memblock_alloc_or_panic() :)
>
> @Andrew, can you please pick this as a fixup?
>
> From 344fec8519e5152c25809c9277b54a68f9cde0e9 Mon Sep 17 00:00:00 2001
> From: "Mike Rapoport (Microsoft)" <rppt@...nel.org>
> Date: Tue, 11 Mar 2025 07:51:27 +0200
> Subject: [PATCH] s390: use memblock_alloc_or_panic() in setup_zero_page()
>
> Signed-off-by: Mike Rapoport (Microsoft) <rppt@...nel.org>
> ---
>  arch/s390/mm/init.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/arch/s390/mm/init.c b/arch/s390/mm/init.c
> index ab8ece3c41f1..c6a97329d7e7 100644
> --- a/arch/s390/mm/init.c
> +++ b/arch/s390/mm/init.c
> @@ -81,9 +81,7 @@ static void __init setup_zero_pages(void)
>         while (order > 2 && (total_pages >> 10) < (1UL << order))
>                 order--;
>
> -       empty_zero_page = (unsigned long)memblock_alloc(PAGE_SIZE << order, order);
> -       if (!empty_zero_page)
> -               panic("Out of memory in setup_zero_pages");
> +       empty_zero_page = (unsigned long)memblock_alloc_or_panic(PAGE_SIZE << order, order);
>

memblock_alloc_or_panic() takes the alignment is in bytes, no? So
shouldn't the second argument be BIT(order)?