Re: [PATCH v1] mm/debug_vm_pgtable: Test pmd_leaf() behavior with pmd_mkinvalid()

[Anshuman Khandual <anshuman.khandual@arm.com>]

Hello Ryan,

On 5/1/24 20:14, Ryan Roberts wrote:
> An invalidated pmd should still cause pmd_leaf() to return true. Let's
> test for that to ensure all arches remain consistent.

This test definitely makes sense.

> 
> Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
> ---
> 
> Hi Andrew,
> 
> This applies on top of v6.9-rc5. It came out of a discussion with Catalin around
> the pmd_mkinvalid() bug (the fix for which I just posted). I've run the new test
> on both arm64 and x86_64.

Right, works on arm64.

> 
> Thanks,
> Ryan
> 
>  mm/debug_vm_pgtable.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index 65c19025da3d..57e9cb0820ab 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -981,6 +981,7 @@ static void __init pmd_thp_tests(struct pgtable_debug_args *args)
>  #ifndef __HAVE_ARCH_PMDP_INVALIDATE
>  	WARN_ON(!pmd_trans_huge(pmd_mkinvalid(pmd_mkhuge(pmd))));
>  	WARN_ON(!pmd_present(pmd_mkinvalid(pmd_mkhuge(pmd))));
> +	WARN_ON(!pmd_leaf(pmd_mkinvalid(pmd_mkhuge(pmd))));
>  #endif /* __HAVE_ARCH_PMDP_INVALIDATE */
>  }

Should not we update descriptions in Documentation/mm/arch_pgtable_helpers.rst
asserting that pmd_mkinvalid() also preserves pmd_leaf() ?