Re: [PATCH] arm: Extend the check for RAM in /dev/mem

[Will Deacon]

On Fri, Jul 12, 2019 at 12:21:21AM +0200, KarimAllah Ahmed wrote:
> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
> index 3645f29..cdc3e8e 100644
> --- a/arch/arm64/mm/mmu.c
> +++ b/arch/arm64/mm/mmu.c
> @@ -78,7 +78,7 @@ void set_swapper_pgd(pgd_t *pgdp, pgd_t pgd)
>  pgprot_t phys_mem_access_prot(struct file *file, unsigned long pfn,
>  			      unsigned long size, pgprot_t vma_prot)
>  {
> -	if (!pfn_valid(pfn))
> +	if (!memblock_is_memory(__pfn_to_phys(pfn)))

This looks broken to me, since it will end up returning 'true' for nomap
memory and we really don't want to map that using writeback attributes.

Will