linux-kernel - Re: [PATCH v4 5/6] mm: Only remove nomap flag for initrd

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Message-ID: <CAMj1kXFn_FKt2jLJOntvT0FBtL9b=VWZdrBFpn48LBMDLy1WBQ@mail.gmail.com>
Date:   Mon, 13 Jun 2022 11:42:44 +0200
From:   Ard Biesheuvel <ardb@...nel.org>
To:     Wupeng Ma <mawupeng1@...wei.com>, Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>
Cc:     Jonathan Corbet <corbet@....net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        X86 ML <x86@...nel.org>, "H. Peter Anvin" <hpa@...or.com>,
        Darren Hart <dvhart@...radead.org>,
        Andy Shevchenko <andy@...radead.org>,
        Mike Rapoport <rppt@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Paul Walmsley <paul.walmsley@...ive.com>, palmer@...belt.com,
        aou@...s.berkeley.edu, paulmck@...nel.org, keescook@...omium.org,
        songmuchun@...edance.com, rdunlap@...radead.org,
        damien.lemoal@...nsource.wdc.com, swboyd@...omium.org,
        wei.liu@...nel.org, robin.murphy@....com, david@...hat.com,
        anshuman.khandual@....com, thunder.leizhen@...wei.com,
        wangkefeng.wang@...wei.com, gpiccoli@...lia.com,
        chenhuacai@...nel.org, geert@...ux-m68k.org,
        vijayb@...ux.microsoft.com, linux-doc@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-efi@...r.kernel.org, platform-driver-x86@...r.kernel.org,
        linux-mm@...ck.org, linux-riscv@...ts.infradead.org
Subject: Re: [PATCH v4 5/6] mm: Only remove nomap flag for initrd

On Mon, 13 Jun 2022 at 10:00, Wupeng Ma <mawupeng1@...wei.com> wrote:
>
> From: Ma Wupeng <mawupeng1@...wei.com>
>
> Commit 177e15f0c144 ("arm64: add the initrd region to the linear mapping explicitly")
> remove all the flags of the memory used by initrd. This is fine since
> MEMBLOCK_MIRROR is not used in arm64.
>
> However with mirrored feature introduced to arm64, this will clear the mirrored
> flag used by initrd, which will lead to error log printed by
> find_zone_movable_pfns_for_nodes() if the lower 4G range has some non-mirrored
> memory.
>
> To solve this problem, only MEMBLOCK_NOMAP flag will be removed via
> memblock_clear_nomap().
>
> Signed-off-by: Ma Wupeng <mawupeng1@...wei.com>

Reviewed-by: Ard Biesheuvel <ardb@...nel.org>

This needs and ack from the arm64 maintainers, please?
And also please fix the subject to include 'arm64'


> ---
>  arch/arm64/mm/init.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c
> index 339ee84e5a61..8456dbae9441 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -350,8 +350,8 @@ void __init arm64_memblock_init(void)
>                         "initrd not fully accessible via the linear mapping -- please check your bootloader ...\n")) {
>                         phys_initrd_size = 0;
>                 } else {
> -                       memblock_remove(base, size); /* clear MEMBLOCK_ flags */
>                         memblock_add(base, size);
> +                       memblock_clear_nomap(base, size);
>                         memblock_reserve(base, size);
>                 }
>         }
> --
> 2.25.1
>