Re: [PATCH v2 2/8] mm/debug_vm_pgtable: add tests for __HAVE_ARCH_PTE_SWP_EXCLUSIVE

[Vlastimil Babka <vbabka@suse.cz>]

On 3/29/22 18:43, David Hildenbrand wrote:
> Let's test that __HAVE_ARCH_PTE_SWP_EXCLUSIVE works as expected.
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>

Acked-by: Vlastimil Babka <vbabka@suse.cz>

> ---
>  mm/debug_vm_pgtable.c | 15 +++++++++++++++
>  1 file changed, 15 insertions(+)
> 
> diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
> index db2abd9e415b..55f1a8dc716f 100644
> --- a/mm/debug_vm_pgtable.c
> +++ b/mm/debug_vm_pgtable.c
> @@ -837,6 +837,19 @@ static void __init pmd_soft_dirty_tests(struct pgtable_debug_args *args) { }
>  static void __init pmd_swap_soft_dirty_tests(struct pgtable_debug_args *args) { }
>  #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
>  
> +static void __init pte_swap_exclusive_tests(struct pgtable_debug_args *args)
> +{
> +#ifdef __HAVE_ARCH_PTE_SWP_EXCLUSIVE
> +	pte_t pte = pfn_pte(args->fixed_pte_pfn, args->page_prot);
> +
> +	pr_debug("Validating PTE swap exclusive\n");
> +	pte = pte_swp_mkexclusive(pte);
> +	WARN_ON(!pte_swp_exclusive(pte));

I guess only this WARN_ON must be guarded by the #ifdef, but doesn't matter
that much - won't gain significantly more test coverage.

> +	pte = pte_swp_clear_exclusive(pte);
> +	WARN_ON(pte_swp_exclusive(pte));
> +#endif /* __HAVE_ARCH_PTE_SWP_EXCLUSIVE */
> +}
> +
>  static void __init pte_swap_tests(struct pgtable_debug_args *args)
>  {
>  	swp_entry_t swp;
> @@ -1288,6 +1301,8 @@ static int __init debug_vm_pgtable(void)
>  	pte_swap_soft_dirty_tests(&args);
>  	pmd_swap_soft_dirty_tests(&args);
>  
> +	pte_swap_exclusive_tests(&args);
> +
>  	pte_swap_tests(&args);
>  	pmd_swap_tests(&args);
>