Re: [PATCH v1 01/11] arm/pgtable: define PFN_PTE_SHIFT on arm and arm64

[Aneesh Kumar K . V]

David Hildenbrand <david@xxxxxxxxxx> writes:

>>>
>>>> If high bits are used for
>>>> something else, then we might produce a garbage PTE on overflow, but that
>>>> shouldn't really matter I concluded for folio_pte_batch() purposes, we'd not
>>>> detect "belongs to this folio batch" either way.
>>>
>>> Exactly.
>>>
>>>>
>>>> Maybe it's likely cleaner to also have a custom pte_next_pfn() on ppc, I just
>>>> hope that we don't lose any other arbitrary PTE bits by doing the pte_pgprot().
>>>
>>> I don't see the need for ppc to implement pte_next_pfn().
>> 
>> Agreed.
>
> So likely we should then do on top for powerpc (whitespace damage):
>
> diff --git a/arch/powerpc/mm/pgtable.c b/arch/powerpc/mm/pgtable.c
> index a04ae4449a025..549a440ed7f65 100644
> --- a/arch/powerpc/mm/pgtable.c
> +++ b/arch/powerpc/mm/pgtable.c
> @@ -220,10 +220,7 @@ void set_ptes(struct mm_struct *mm, unsigned long addr, pte_t *ptep,
>                          break;
>                  ptep++;
>                  addr += PAGE_SIZE;
> -               /*
> -                * increment the pfn.
> -                */
> -               pte = pfn_pte(pte_pfn(pte) + 1, pte_pgprot((pte)));
> +               pte = pte_next_pfn(pte);
>          }
>   }

Agreed.

-aneesh