linux-kernel - Re: [PATCH v3 3/3] Turn off test_uffdio_wp if CONFIG_PTE_MARKER_UFFD

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Date: Wed, 26 Jun 2024 09:53:20 -0400
From: Peter Xu <peterx@...hat.com>
To: Audra Mitchell <audra@...hat.com>
Cc: viro@...iv.linux.org.uk, brauner@...nel.org, jack@...e.cz,
	aarcange@...hat.com, akpm@...ux-foundation.org,
	rppt@...ux.vnet.ibm.com, shli@...com, linux-fsdevel@...r.kernel.org,
	linux-kernel@...r.kernel.org, shuah@...nel.org,
	linux-kselftest@...r.kernel.org, raquini@...hat.com,
	linux-mm@...ck.org
Subject: Re: [PATCH v3 3/3] Turn off test_uffdio_wp if
 CONFIG_PTE_MARKER_UFFD_WP is not configured.

On Wed, Jun 26, 2024 at 09:05:13AM -0400, Audra Mitchell wrote:
> If CONFIG_PTE_MARKER_UFFD_WP is disabled, then we turn off three features
> in userfaultfd_api (UFFD_FEATURE_WP_HUGETLBFS_SHMEM,
> UFFD_FEATURE_WP_UNPOPULATED, and UFFD_FEATURE_WP_ASYNC). Currently this
> test always will call uffdio_regsiter with the flag
> UFFDIO_REGISTER_MODE_WP. However, the kernel ensures in vma_can_userfault
> that if the feature UFFD_FEATURE_WP_HUGETLBFS_SHMEM is disabled, only
> allow the VM_UFFD_WP on anonymous vmas, meaning our call to
> uffdio_regsiter will fail. We still want to be able to run the test even
> if we have CONFIG_PTE_MARKER_UFFD_WP disabled, so check to see if the
> feature UFFD_FEATURE_WP_HUGETLBFS_SHMEM has been turned off in the test
> and if so, disable us from calling uffdio_regsiter with the flag
> UFFDIO_REGISTER_MODE_WP.
> 
> Signed-off-by: Audra Mitchell <audra@...hat.com>

Reviewed-by: Peter Xu <peterx@...hat.com>

> ---
>  tools/testing/selftests/mm/uffd-stress.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/tools/testing/selftests/mm/uffd-stress.c b/tools/testing/selftests/mm/uffd-stress.c
> index b9b6d858eab8..3266ae885f75 100644
> --- a/tools/testing/selftests/mm/uffd-stress.c
> +++ b/tools/testing/selftests/mm/uffd-stress.c
> @@ -419,6 +419,9 @@ static void parse_test_type_arg(const char *raw_type)
>  	test_uffdio_wp = test_uffdio_wp &&
>  		(features & UFFD_FEATURE_PAGEFAULT_FLAG_WP);
>  
> +	if (test_type != TEST_ANON && !(features & UFFD_FEATURE_WP_HUGETLBFS_SHMEM))
> +		test_uffdio_wp = false;
> +
>  	close(uffd);
>  	uffd = -1;
>  }
> -- 
> 2.44.0
> 

-- 
Peter Xu