Re: [PATCH 08/16] debug_vm_pgtable/set_pmd: Don't use set_pmd_at to update an existing pmd entry

[Anshuman Khandual]

On 08/12/2020 12:03 PM, Aneesh Kumar K.V wrote:
> set_pmd_at() should not be used to set a pte entry at locations that
> already holds a valid pte entry. Architectures like ppc64 don't do TLB
> invalidate in set_pmd_at() and hence expect it to be used to set locations
> that are not a valid PTE.
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.ku...@linux.ibm.com>
> ---
>  mm/debug_vm_pgtable.c | 5 +----
>  1 file changed, 1 insertion(+), 4 deletions(-)
> 
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index cd609a212dd4..60bf876081b8 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -164,8 +164,6 @@ static void __init pmd_advanced_tests(struct mm_struct 
> *mm,
>       pmd = READ_ONCE(*pmdp);
>       WARN_ON(pmd_write(pmd));
>  
> -     pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
> -     set_pmd_at(mm, vaddr, pmdp, pmd);
>       pmdp_huge_get_and_clear(mm, vaddr, pmdp);
>       pmd = READ_ONCE(*pmdp);
>       WARN_ON(!pmd_none(pmd));
> @@ -180,12 +178,11 @@ static void __init pmd_advanced_tests(struct mm_struct 
> *mm,
>       pmd = READ_ONCE(*pmdp);
>       WARN_ON(!(pmd_write(pmd) && pmd_dirty(pmd)));
>  
> -     pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
> -     set_pmd_at(mm, vaddr, pmdp, pmd);
>       pmdp_huge_get_and_clear_full(vma, vaddr, pmdp, 1);
>       pmd = READ_ONCE(*pmdp);
>       WARN_ON(!pmd_none(pmd));
>  
> +     pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
>       pmd = pmd_mkyoung(pmd);
>       set_pmd_at(mm, vaddr, pmdp, pmd);
>       pmdp_test_and_clear_young(vma, vaddr, pmdp);
> 

Very similar to [PATCH 3/16] wrt set_pte_at(), please fold it.