Subject: Re: [PATCH 04/16] debug_vm_pgtables/hugevmap: Use the arch helper to identify huge vmap support.

From: Anshuman Khandual <[email-masked]>
Date: Wed, 12 Aug 2020 16:00:15 +0530

On 08/12/2020 12:03 PM, Aneesh Kumar K.V wrote:
> ppc64 supports huge vmap only with radix translation. Hence use arch helper
> to determine the huge vmap support.
> 
> Signed-off-by: Aneesh Kumar K.V <[email-masked]>
> ---
>  mm/debug_vm_pgtable.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index 02a7c20aa4a2..679bb3d289a3 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -206,7 +206,7 @@ static void __init pmd_huge_tests(pmd_t *pmdp, unsigned long pfn, pgprot_t prot)
>  {
>  	pmd_t pmd;
>  
> -	if (!IS_ENABLED(CONFIG_HAVE_ARCH_HUGE_VMAP))
> +	if (!arch_ioremap_pmd_supported())
>  		return;
>  
>  	pr_debug("Validating PMD huge\n");
> 

Problem is arch_ioremap_pmd_supported() symbol which should also be
explicitly included via <linux/io.h>, is not available without the
config CONFIG_HAVE_ARCH_HUGE_VMAP. ioremap_pmd_enabled() should have
been better here and has a fallback for !CONFIG_HAVE_ARCH_HUGE_VMAP.
But then the symbol is local to that file. Unless we would like to
make ioremap_pxx_enabled generally available, the remaining option
would be to wrap pxx_huge_tests() with CONFIG_HAVE_ARCH_HUGE_VMAP.
Similar changes should also be done for pud_huge_tests() as well.