Re: [PATCH] selftests/mm: refactor common code and improve test skipping in guard_region

[Lorenzo Stoakes <lorenzo.stoakes@oracle.com>]

On Mon, Jul 14, 2025 at 09:00:09PM +0800, wang lian wrote:
> Move the generic `FORCE_READ` macro from `guard-regions.c` to the shared
> `vm_util.h` header to promote code reuse.
>
> In `guard-regions.c`, replace `ksft_exit_skip()` with the `SKIP()` macro
> to ensure only the current test is skipped on permission failure, instead
> of terminating the entire test binary.
>
> Signed-off-by: wang lian <lianux.mm@gmail.com>

LGTM, so:

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>

> ---
>  tools/testing/selftests/mm/guard-regions.c | 9 +--------
>  tools/testing/selftests/mm/vm_util.h       | 7 +++++++
>  2 files changed, 8 insertions(+), 8 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/guard-regions.c b/tools/testing/selftests/mm/guard-regions.c
> index 93af3d3760f9..b0d42eb04e3a 100644
> --- a/tools/testing/selftests/mm/guard-regions.c
> +++ b/tools/testing/selftests/mm/guard-regions.c
> @@ -35,13 +35,6 @@
>  static volatile sig_atomic_t signal_jump_set;
>  static sigjmp_buf signal_jmp_buf;
>
> -/*
> - * Ignore the checkpatch warning, we must read from x but don't want to do
> - * anything with it in order to trigger a read page fault. We therefore must use
> - * volatile to stop the compiler from optimising this away.
> - */
> -#define FORCE_READ(x) (*(volatile typeof(x) *)x)
> -
>  /*
>   * How is the test backing the mapping being tested?
>   */
> @@ -582,7 +575,7 @@ TEST_F(guard_regions, process_madvise)
>
>  	/* OK we don't have permission to do this, skip. */
>  	if (count == -1 && errno == EPERM)
> -		ksft_exit_skip("No process_madvise() permissions, try running as root.\n");
> +		SKIP(return, "No process_madvise() permissions, try running as root.\n");

Lol oops! :P yes thi is better.

>
>  	/* Returns the number of bytes advised. */
>  	ASSERT_EQ(count, 6 * page_size);
> diff --git a/tools/testing/selftests/mm/vm_util.h b/tools/testing/selftests/mm/vm_util.h
> index 2b154c287591..c20298ae98ea 100644
> --- a/tools/testing/selftests/mm/vm_util.h
> +++ b/tools/testing/selftests/mm/vm_util.h
> @@ -18,6 +18,13 @@
>  #define PM_SWAP                       BIT_ULL(62)
>  #define PM_PRESENT                    BIT_ULL(63)
>
> +/*
> + * Ignore the checkpatch warning, we must read from x but don't want to do
> + * anything with it in order to trigger a read page fault. We therefore must use
> + * volatile to stop the compiler from optimising this away.
> + */
> +#define FORCE_READ(x) (*(volatile typeof(x) *)x)
> +

Cool makes sense to share this.

If this contradicts previous review, take this review to be the correct one
:P

>  extern unsigned int __page_size;
>  extern unsigned int __page_shift;
>
> --
> 2.43.0
>