Re: [PATCH v2 17/20] mm: free_area_init: allow defining max_zone_pfn in descending order

[Vineet Gupta <Vineet.Gupta1@xxxxxxxxxxxx>]

On 5/7/20 1:59 PM, Mike Rapoport wrote:
> On Tue, May 05, 2020 at 11:15:22PM +0300, Mike Rapoport wrote:
>> On Tue, May 05, 2020 at 06:07:46PM +0000, Vineet Gupta wrote:
>>> On 5/5/20 2:19 AM, Mike Rapoport wrote:
>>>  - Is it not better to have the core retain the flexibility just in case
>> If the requirement to have support for 3-banks is a theoretical
>> possibility, I would prefer to adjust ARC's version of
>> arch_has_descending_max_zone_pfns() to cope with either of 2-banks
>> configuration (PAE40 and non-PAE40) and deal with the third bank when/if
>> it actually materializes.

Fair enough.

> The fix below should take care of any 2-bank configurations. 
> This is vs. current mmotm.
>
> From eb8124fb3584607d1036b7ae00c8092ae43e480d Mon Sep 17 00:00:00 2001
> From: Mike Rapoport <rppt@xxxxxxxxxxxxx>
> Date: Thu, 7 May 2020 23:44:15 +0300
> Subject: [PATCH] arc: free_area_init(): take into account PAE40 mode
>
> The arch_has_descending_max_zone_pfns() does not take into account physical
> memory layout for PAE40 configuration.
> With PAE40 enabled, the HIGHMEM is actually higher than NORMAL and
> arch_has_descending_max_zone_pfns() should return false in this case.
>
> Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>

LGTM.

Acked-by: Vineet Gupta <vgupta@xxxxxxxxxxxx>

Thx,

> ---
>  arch/arc/mm/init.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c
> index 386959bac3d2..e7bdc2ac1c87 100644
> --- a/arch/arc/mm/init.c
> +++ b/arch/arc/mm/init.c
> @@ -79,7 +79,7 @@ void __init early_init_dt_add_memory_arch(u64 base, u64 size)
>  
>  bool arch_has_descending_max_zone_pfns(void)
>  {
> -	return true;
> +	return !IS_ENABLED(CONFIG_ARC_HAS_PAE40);
>  }
>  
>  /*