linux-kernel - Re: [PATCH v5 1/9] MIPS: Avoid future duplicate elf core header reservation

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Date:   Mon, 16 Aug 2021 08:52:12 +0300
From:   Mike Rapoport <rppt@...nel.org>
To:     Geert Uytterhoeven <geert+renesas@...der.be>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Russell King <linux@...linux.org.uk>,
        Nicolas Pitre <nico@...xnic.net>,
        Ard Biesheuvel <ardb@...nel.org>,
        Linus Walleij <linus.walleij@...aro.org>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        Nick Kossifidis <mick@....forth.gr>,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        Albert Ou <aou@...s.berkeley.edu>,
        Frank Rowand <frowand.list@...il.com>,
        Dave Young <dyoung@...hat.com>, Baoquan He <bhe@...hat.com>,
        Vivek Goyal <vgoyal@...hat.com>, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-mips@...r.kernel.org,
        linux-riscv@...ts.infradead.org, kexec@...ts.infradead.org,
        linux-renesas-soc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/9] MIPS: Avoid future duplicate elf core header
 reservation

Hi Geert,

On Wed, Aug 11, 2021 at 10:50:59AM +0200, Geert Uytterhoeven wrote:
> Prepare for early_init_fdt_scan_reserved_mem() reserving the memory
> occupied by an elf core header described in the device tree.
> As arch_mem_init() calls early_init_fdt_scan_reserved_mem() before
> mips_reserve_vmcore(), the latter needs to check if the memory has
> already been reserved before.

Doing memblock_reserve() for the same region is usually fine, did you
encounter any issues without this patch?
 
> Note that mips_reserve_vmcore() cannot just be removed, as not all MIPS
> systems use DT.
> 
> Signed-off-by: Geert Uytterhoeven <geert+renesas@...der.be>
> ---
> v5:
>   - New.
> ---
>  arch/mips/kernel/setup.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/mips/kernel/setup.c b/arch/mips/kernel/setup.c
> index 23a140327a0bac1b..4693add05743d78b 100644
> --- a/arch/mips/kernel/setup.c
> +++ b/arch/mips/kernel/setup.c
> @@ -429,7 +429,8 @@ static void __init mips_reserve_vmcore(void)
>  	pr_info("Reserving %ldKB of memory at %ldKB for kdump\n",
>  		(unsigned long)elfcorehdr_size >> 10, (unsigned long)elfcorehdr_addr >> 10);
>  
> -	memblock_reserve(elfcorehdr_addr, elfcorehdr_size);
> +	if (!memblock_is_region_reserved(elfcorehdr_addr, elfcorehdr_size)
> +		memblock_reserve(elfcorehdr_addr, elfcorehdr_size);
>  #endif
>  }
>  
> -- 
> 2.25.1
> 

-- 
Sincerely yours,
Mike.