Re: [PATCH V2] mm/debug_vm_pgtable: Add [pte|pmd]_mkwrite_novma() tests

["Huang, Ying" <ying.huang@linux.alibaba.com>]

Anshuman Khandual <anshuman.khandual@arm.com> writes:

> Add some [pte|pmd]_mkwrite_novma() relevant tests.
>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: David Hildenbrand <david@redhat.com>
> Cc: Huang Ying <ying.huang@linux.alibaba.com>
> Cc: linux-mm@kvack.org
> Cc: linux-kernel@vger.kernel.org
> Suggested-by: Catalin Marinas <catalin.marinas@arm.com>
> Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
> ---
> These tests clear on arm64 platform after the following recent patch.
>
> https://lore.kernel.org/all/20251015023712.46598-1-ying.huang@linux.alibaba.com/
>
> Changes in V2:
>
> - Added a new test combination per Huang
>
> Changes in V1:
>
> https://lore.kernel.org/all/20251021024424.2390325-1-anshuman.khandual@arm.com/
>
>  mm/debug_vm_pgtable.c | 12 ++++++++++++
>  1 file changed, 12 insertions(+)
>
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index 830107b6dd08..def344bb4a32 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -102,6 +102,12 @@ static void __init pte_basic_tests(struct pgtable_debug_args *args, int idx)
>  	WARN_ON(pte_write(pte_wrprotect(pte_mkwrite(pte, args->vma))));
>  	WARN_ON(pte_dirty(pte_wrprotect(pte_mkclean(pte))));
>  	WARN_ON(!pte_dirty(pte_wrprotect(pte_mkdirty(pte))));
> +
> +	WARN_ON(!pte_dirty(pte_mkwrite_novma(pte_mkdirty(pte))));
> +	WARN_ON(pte_dirty(pte_mkwrite_novma(pte_mkclean(pte))));
> +	WARN_ON(!pte_write(pte_mkdirty(pte_mkwrite_novma(pte))));

Why do you use

pte_mkwrite_novma(pte)

instead of

pte_mkwrite(pte, args->vma)

?

> +	WARN_ON(!pte_write(pte_mkwrite_novma(pte_wrprotect(pte))));
> +	WARN_ON(pte_write(pte_wrprotect(pte_mkwrite_novma(pte))));
>  }
>  
>  static void __init pte_advanced_tests(struct pgtable_debug_args *args)
> @@ -195,6 +201,12 @@ static void __init pmd_basic_tests(struct pgtable_debug_args *args, int idx)
>  	WARN_ON(pmd_write(pmd_wrprotect(pmd_mkwrite(pmd, args->vma))));
>  	WARN_ON(pmd_dirty(pmd_wrprotect(pmd_mkclean(pmd))));
>  	WARN_ON(!pmd_dirty(pmd_wrprotect(pmd_mkdirty(pmd))));
> +
> +	WARN_ON(pmd_dirty(pmd_mkwrite_novma(pmd_mkclean(pmd))));
> +	WARN_ON(!pmd_write(pmd_mkdirty(pmd_mkwrite_novma(pmd))));
> +	WARN_ON(!pmd_write(pmd_mkwrite_novma(pmd_wrprotect(pmd))));
> +	WARN_ON(pmd_write(pmd_wrprotect(pmd_mkwrite_novma(pmd))));
> +
>  	/*
>  	 * A huge page does not point to next level page table
>  	 * entry. Hence this must qualify as pmd_bad().

---
Best Regards,
Huang, Ying