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Re: [PATCH] ARM: memblock limit must be pmd-aligned

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On 06/26/2017 10:23 AM, Doug Berger wrote:
> There is a path through the adjust_lowmem_bounds() routine where if all
> memory regions start and end on pmd-aligned addresses the memblock_limit
> will be set to arm_lowmem_limit.
> 
> However, since arm_lowmem_limit can be affected by the vmalloc early
> parameter, the value of arm_lowmem_limit may not be pmd-aligned. This
> commit corrects this oversight such that memblock_limit is always rounded
> down to pmd-alignment.
> 
> The pmd containing arm_lowmem_limit is cleared by prepare_page_table()
> and without this commit it is possible for early_alloc() to allocate
> unmapped memory in that range when mapping the lowmem.
> 

Do you have an example system or configuration where you see this
crash?

Thanks,
Laura

> Signed-off-by: Doug Berger <opendmb@gmail.com>
> ---
>  arch/arm/mm/mmu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm/mm/mmu.c b/arch/arm/mm/mmu.c
> index 31af3cb59a60..2ae4f9c9d757 100644
> --- a/arch/arm/mm/mmu.c
> +++ b/arch/arm/mm/mmu.c
> @@ -1226,7 +1226,7 @@ void __init adjust_lowmem_bounds(void)
>  	if (memblock_limit)
>  		memblock_limit = round_down(memblock_limit, PMD_SIZE);
>  	if (!memblock_limit)
> -		memblock_limit = arm_lowmem_limit;
> +		memblock_limit = round_down(arm_lowmem_limit, PMD_SIZE);
>  
>  	if (!IS_ENABLED(CONFIG_HIGHMEM) || cache_is_vipt_aliasing()) {
>  		if (memblock_end_of_DRAM() > arm_lowmem_limit) {
> 

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[PATCH] ARM: memblock limit must be pmd-aligned Doug Berger <opendmb@gmail.com> - 2017-06-26 19:30 +0200
  Re: [PATCH] ARM: memblock limit must be pmd-aligned Laura Abbott <labbott@redhat.com> - 2017-06-27 01:50 +0200
    Re: [PATCH] ARM: memblock limit must be pmd-aligned Doug Berger <opendmb@gmail.com> - 2017-06-27 03:00 +0200
      Re: [PATCH] ARM: memblock limit must be pmd-aligned Mark Rutland <mark.rutland@arm.com> - 2017-06-27 13:10 +0200
        Re: [PATCH] ARM: memblock limit must be pmd-aligned Doug Berger <opendmb@gmail.com> - 2017-06-27 19:00 +0200
          Re: [PATCH] ARM: memblock limit must be pmd-aligned Russell King - ARM Linux <linux@armlinux.org.uk> - 2017-06-27 19:10 +0200
          Re: [PATCH] ARM: memblock limit must be pmd-aligned Mark Rutland <mark.rutland@arm.com> - 2017-06-27 19:20 +0200

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