linux-kernel - Re: [PATCH v3 6/6] efi: Disable mirror feature if kernelcore is not specified

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Message-ID: <CAMj1kXGMHn_jsMe2WxWZ-s_QV==1tc5k=xpbNXuDbGp0qF534w@mail.gmail.com>
Date:   Fri, 10 Jun 2022 13:20:34 +0200
From:   Ard Biesheuvel <ardb@...nel.org>
To:     Wupeng Ma <mawupeng1@...wei.com>
Cc:     Jonathan Corbet <corbet@....net>, Will Deacon <will@...nel.org>,
        Catalin Marinas <catalin.marinas@....com>,
        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 Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        "Paul E. McKenney" <paulmck@...nel.org>,
        Kees Cook <keescook@...omium.org>, songmuchun@...edance.com,
        Randy Dunlap <rdunlap@...radead.org>,
        damien.lemoal@...nsource.wdc.com,
        Stephen Boyd <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 Uytterhoeven <geert@...ux-m68k.org>,
        chenzhou10@...wei.com, 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 v3 6/6] efi: Disable mirror feature if kernelcore is not specified

On Tue, 7 Jun 2022 at 11:16, Wupeng Ma <mawupeng1@...wei.com> wrote:
>
> From: Ma Wupeng <mawupeng1@...wei.com>
>
> If system have some mirrored memory and mirrored feature is not specified
> in boot parameter, the basic mirrored feature will be enabled and this will
> lead to the following situations:
>
> - memblock memory allocation prefers mirrored region. This may have some
>   unexpected influence on numa affinity.
>
> - contiguous memory will be split into several parts if parts of them
>   is mirrored memory via memblock_mark_mirror().
>
> To fix this, variable mirrored_kernelcore will be checked before calling
> efi_find_mirror() which will enable basic mirrored feature and this
> variable is true if kernelcore=mirror is added in the kernel parameters.
>
> Signed-off-by: Ma Wupeng <mawupeng1@...wei.com>

This seems like the wrong place to do this. If mirrored memory is
irrelevant to memblock, it should ignore the attribute. So I think
this check belongs in mm/memblock.c instead.


> ---
>  drivers/firmware/efi/efi.c | 3 +++
>  include/linux/mm.h         | 2 ++
>  mm/page_alloc.c            | 2 +-
>  3 files changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index 79c232e07de7..8a5edcb0dd82 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -454,6 +454,9 @@ void __init efi_find_mirror(void)
>         if (!efi_enabled(EFI_MEMMAP))
>                 return;
>
> +       if (!mirrored_kernelcore)
> +               return;
> +
>         for_each_efi_memory_desc(md) {
>                 unsigned long long start = md->phys_addr;
>                 unsigned long long size = md->num_pages << EFI_PAGE_SHIFT;
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index bc8f326be0ce..741ac7d022c3 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2540,6 +2540,8 @@ extern void get_pfn_range_for_nid(unsigned int nid,
>                         unsigned long *start_pfn, unsigned long *end_pfn);
>  extern unsigned long find_min_pfn_with_active_regions(void);
>
> +extern bool mirrored_kernelcore;
> +
>  #ifndef CONFIG_NUMA
>  static inline int early_pfn_to_nid(unsigned long pfn)
>  {
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index e008a3df0485..cf6f70aba787 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -356,7 +356,7 @@ static unsigned long required_kernelcore_percent __initdata;
>  static unsigned long required_movablecore __initdata;
>  static unsigned long required_movablecore_percent __initdata;
>  static unsigned long zone_movable_pfn[MAX_NUMNODES] __initdata;
> -static bool mirrored_kernelcore __meminitdata;
> +bool mirrored_kernelcore __meminitdata;
>
>  /* movable_zone is the "real" zone pages in ZONE_MOVABLE are taken from */
>  int movable_zone;
> --
> 2.25.1
>