[PATCH 07/16] debug_vm_pgtable/THP: Mark the pte entry huge before using set_pud_at

[Anshuman Khandual]

On 08/12/2020 12:03 PM, Aneesh Kumar K.V wrote:
> kernel expect entries to be marked huge before we use set_pud_at().
> 
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar at linux.ibm.com>
> ---
>  mm/debug_vm_pgtable.c | 11 +++++++----
>  1 file changed, 7 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index b6aca2526e01..cd609a212dd4 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -265,7 +265,7 @@ static void __init pud_advanced_tests(struct mm_struct *mm,
>  				      unsigned long pfn, unsigned long vaddr,
>  				      pgprot_t prot)
>  {
> -	pud_t pud = pfn_pud(pfn, prot);
> +	pud_t pud;
>  
>  	if (!has_transparent_hugepage())
>  		return;
> @@ -274,25 +274,28 @@ static void __init pud_advanced_tests(struct mm_struct *mm,
>  	/* Align the address wrt HPAGE_PUD_SIZE */
>  	vaddr = (vaddr & HPAGE_PUD_MASK) + HPAGE_PUD_SIZE;
>  
> +	pud = pud_mkhuge(pfn_pud(pfn, prot));
>  	set_pud_at(mm, vaddr, pudp, pud);
>  	pudp_set_wrprotect(mm, vaddr, pudp);
>  	pud = READ_ONCE(*pudp);
>  	WARN_ON(pud_write(pud));
>  
>  #ifndef __PAGETABLE_PMD_FOLDED
> -	pud = pfn_pud(pfn, prot);
> +
> +	pud = pud_mkhuge(pfn_pud(pfn, prot));
>  	set_pud_at(mm, vaddr, pudp, pud);
>  	pudp_huge_get_and_clear(mm, vaddr, pudp);
>  	pud = READ_ONCE(*pudp);
>  	WARN_ON(!pud_none(pud));
>  
> -	pud = pfn_pud(pfn, prot);
> +	pud = pud_mkhuge(pfn_pud(pfn, prot));
>  	set_pud_at(mm, vaddr, pudp, pud);
>  	pudp_huge_get_and_clear_full(mm, vaddr, pudp, 1);
>  	pud = READ_ONCE(*pudp);
>  	WARN_ON(!pud_none(pud));
>  #endif /* __PAGETABLE_PMD_FOLDED */
> -	pud = pfn_pud(pfn, prot);
> +
> +	pud = pud_mkhuge(pfn_pud(pfn, prot));
>  	pud = pud_wrprotect(pud);
>  	pud = pud_mkclean(pud);
>  	set_pud_at(mm, vaddr, pudp, pud);
> 

Looks very similar to the previous patch, hence please fold it back.
Seems fair enough that pxx_set_at() expects given entry to be huge.
But would need to run them across enabled platforms to be sure.