[PATCH 10/16] debug_vm_pgtable/thp: Use page table depost/withdraw with THP

[Anshuman Khandual]

On 08/12/2020 12:03 PM, Aneesh Kumar K.V wrote:
> Architectures like ppc64 use deposited page table while updating the huge pte
> entries.
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
> ---
>  mm/debug_vm_pgtable.c | 8 ++++++--
>  1 file changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index 644d28861ce9..48475d288df1 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -147,7 +147,7 @@ static void __init pmd_basic_tests(unsigned long pfn, pgprot_t prot)
>  static void __init pmd_advanced_tests(struct mm_struct *mm,
>  				      struct vm_area_struct *vma, pmd_t *pmdp,
>  				      unsigned long pfn, unsigned long vaddr,
> -				      pgprot_t prot)
> +				      pgprot_t prot, pgtable_t pgtable)
>  {
>  	pmd_t pmd;
>  
> @@ -158,6 +158,8 @@ static void __init pmd_advanced_tests(struct mm_struct *mm,
>  	/* Align the address wrt HPAGE_PMD_SIZE */
>  	vaddr = (vaddr & HPAGE_PMD_MASK) + HPAGE_PMD_SIZE;
>  
> +	pgtable_trans_huge_deposit(mm, pmdp, pgtable);
> +
>  	pmd = pmd_mkhuge(pfn_pmd(pfn, prot));
>  	set_pmd_at(mm, vaddr, pmdp, pmd);
>  	pmdp_set_wrprotect(mm, vaddr, pmdp);
> @@ -188,6 +190,8 @@ static void __init pmd_advanced_tests(struct mm_struct *mm,
>  	pmdp_test_and_clear_young(vma, vaddr, pmdp);
>  	pmd = READ_ONCE(*pmdp);
>  	WARN_ON(pmd_young(pmd));
> +
> +	pgtable = pgtable_trans_huge_withdraw(mm, pmdp);
>  }
>  
>  static void __init pmd_leaf_tests(unsigned long pfn, pgprot_t prot)
> @@ -1002,7 +1006,7 @@ static int __init debug_vm_pgtable(void)
>  	pgd_clear_tests(mm, pgdp);
>  
>  	pte_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot);
> -	pmd_advanced_tests(mm, vma, pmdp, pmd_aligned, vaddr, prot);
> +	pmd_advanced_tests(mm, vma, pmdp, pmd_aligned, vaddr, prot, saved_ptep);
>  	pud_advanced_tests(mm, vma, pudp, pud_aligned, vaddr, prot);
>  	hugetlb_advanced_tests(mm, vma, ptep, pte_aligned, vaddr, prot);
>  
> 

Makes sense, if it is required for THP to work correctly but needs to be tested
across enabled platforms. Why should not the same apply for pud_advanced_tests()
on platforms that supports PUD based THP.