linux-kernel - Re: [PATCH] arm64/mm: Poison initmem while freeing with free_reserved

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Message-ID: <600676fd-1b39-74f4-49a7-3c807ee24cff@arm.com>
Date:   Fri, 4 Oct 2019 11:19:03 +0100
From:   Steven Price <steven.price@....com>
To:     Anshuman Khandual <anshuman.khandual@....com>,
        linux-arm-kernel@...ts.infradead.org
Cc:     Mark Rutland <mark.rutland@....com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] arm64/mm: Poison initmem while freeing with
 free_reserved_area()

On 04/10/2019 05:23, Anshuman Khandual wrote:
> Platform implementation for free_initmem() should poison the memory while
> freeing it up. Hence pass across POISON_FREE_INITMEM while calling into
> free_reserved_area(). The same is being followed in the generic fallback
> for free_initmem() and some other platforms overriding it.
> 
> Cc: Catalin Marinas <catalin.marinas@....com>
> Cc: Will Deacon <will@...nel.org>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Anshuman Khandual <anshuman.khandual@....com>

Is there a good reason you haven't made a similar change to
free_initrd_mem() - the same logic seems to apply. However this change
looks fine to me.

Reviewed-by: Steven Price <steven.price@....com>

> ---
>  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 45c00a54909c..ea7d38011e83 100644
> --- a/arch/arm64/mm/init.c
> +++ b/arch/arm64/mm/init.c
> @@ -571,7 +571,7 @@ void free_initmem(void)
>  {
>  	free_reserved_area(lm_alias(__init_begin),
>  			   lm_alias(__init_end),
> -			   0, "unused kernel");
> +			   POISON_FREE_INITMEM, "unused kernel");
>  	/*
>  	 * Unmap the __init region but leave the VM area in place. This
>  	 * prevents the region from being reused for kernel modules, which
>