Re: [PATCH 1/6] selftests/mm: Report errno when things fail

[Dev Jain <dev.jain@xxxxxxx>]

On 20/02/25 8:33 pm, Brendan Jackman wrote:
> Just reporting failure doesn't tell you what went wrong. This can fail
> in different ways so report errno to help the reader get started
> debugging.

IMHO it would be even better if we reported strerror(errno).

> Signed-off-by: Brendan Jackman <jackmanb@xxxxxxxxxx>
> ---
>   tools/testing/selftests/mm/gup_longterm.c | 32 +++++++++++++++----------------
>   1 file changed, 16 insertions(+), 16 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/gup_longterm.c b/tools/testing/selftests/mm/gup_longterm.c
> index 9423ad439a6140163bdef2974615bb86406a8c14..46a2139b3a646f6c050eb031a770f615be76c433 100644
> --- a/tools/testing/selftests/mm/gup_longterm.c
> +++ b/tools/testing/selftests/mm/gup_longterm.c
> @@ -96,13 +96,13 @@ static void do_test(int fd, size_t size, enum test_type type, bool shared)
>   	int ret;
>   
>   	if (ftruncate(fd, size)) {
> -		ksft_test_result_fail("ftruncate() failed\n");
> +		ksft_test_result_fail("ftruncate() failed (%d)\n", errno);
>   		return;
>   	}
>   
>   	if (fallocate(fd, 0, 0, size)) {
>   		if (size == pagesize)
> -			ksft_test_result_fail("fallocate() failed\n");
> +			ksft_test_result_fail("fallocate() failed (%d)\n", errno);
>   		else
>   			ksft_test_result_skip("need more free huge pages\n");
>   		return;
> @@ -112,7 +112,7 @@ static void do_test(int fd, size_t size, enum test_type type, bool shared)
>   		   shared ? MAP_SHARED : MAP_PRIVATE, fd, 0);
>   	if (mem == MAP_FAILED) {
>   		if (size == pagesize || shared)
> -			ksft_test_result_fail("mmap() failed\n");
> +			ksft_test_result_fail("mmap() failed (%d)\n", errno);
>   		else
>   			ksft_test_result_skip("need more free huge pages\n");
>   		return;
> @@ -130,7 +130,7 @@ static void do_test(int fd, size_t size, enum test_type type, bool shared)
>   		 */
>   		ret = mprotect(mem, size, PROT_READ);
>   		if (ret) {
> -			ksft_test_result_fail("mprotect() failed\n");
> +			ksft_test_result_fail("mprotect() failed (%d)\n", errno);
>   			goto munmap;
>   		}
>   		/* FALLTHROUGH */
> @@ -165,18 +165,18 @@ static void do_test(int fd, size_t size, enum test_type type, bool shared)
>   		args.flags |= rw ? PIN_LONGTERM_TEST_FLAG_USE_WRITE : 0;
>   		ret = ioctl(gup_fd, PIN_LONGTERM_TEST_START, &args);
>   		if (ret && errno == EINVAL) {
> -			ksft_test_result_skip("PIN_LONGTERM_TEST_START failed\n");
> +			ksft_test_result_skip("PIN_LONGTERM_TEST_START failed (EINVAL)n");
>   			break;
>   		} else if (ret && errno == EFAULT) {
>   			ksft_test_result(!should_work, "Should have failed\n");
>   			break;
>   		} else if (ret) {
> -			ksft_test_result_fail("PIN_LONGTERM_TEST_START failed\n");
> +			ksft_test_result_fail("PIN_LONGTERM_TEST_START failed (%d)\n", errno);
>   			break;
>   		}
>   
>   		if (ioctl(gup_fd, PIN_LONGTERM_TEST_STOP))
> -			ksft_print_msg("[INFO] PIN_LONGTERM_TEST_STOP failed\n");
> +			ksft_print_msg("[INFO] PIN_LONGTERM_TEST_STOP failed (%d)\n", errno);
>   
>   		/*
>   		 * TODO: if the kernel ever supports long-term R/W pinning on
> @@ -202,7 +202,7 @@ static void do_test(int fd, size_t size, enum test_type type, bool shared)
>   		/* Skip on errors, as we might just lack kernel support. */
>   		ret = io_uring_queue_init(1, &ring, 0);
>   		if (ret < 0) {
> -			ksft_test_result_skip("io_uring_queue_init() failed\n");
> +			ksft_test_result_skip("io_uring_queue_init() failed (%d)\n", errno);
>   			break;
>   		}
>   		/*
> @@ -215,13 +215,13 @@ static void do_test(int fd, size_t size, enum test_type type, bool shared)
>   		/* Only new kernels return EFAULT. */
>   		if (ret && (errno == ENOSPC || errno == EOPNOTSUPP ||
>   			    errno == EFAULT)) {
> -			ksft_test_result(!should_work, "Should have failed\n");
> +			ksft_test_result(!should_work, "Should have failed (%d)\n", errno);
>   		} else if (ret) {
>   			/*
>   			 * We might just lack support or have insufficient
>   			 * MEMLOCK limits.
>   			 */
> -			ksft_test_result_skip("io_uring_register_buffers() failed\n");
> +			ksft_test_result_skip("io_uring_register_buffers() failed (%d)\n", errno);
>   		} else {
>   			ksft_test_result(should_work, "Should have worked\n");
>   			io_uring_unregister_buffers(&ring);
> @@ -249,7 +249,7 @@ static void run_with_memfd(test_fn fn, const char *desc)
>   
>   	fd = memfd_create("test", 0);
>   	if (fd < 0) {
> -		ksft_test_result_fail("memfd_create() failed\n");
> +		ksft_test_result_fail("memfd_create() failed (%d)\n", errno);
>   		return;
>   	}
>   
> @@ -266,13 +266,13 @@ static void run_with_tmpfile(test_fn fn, const char *desc)
>   
>   	file = tmpfile();
>   	if (!file) {
> -		ksft_test_result_fail("tmpfile() failed\n");
> +		ksft_test_result_fail("tmpfile() failed (%d)\n", errno);
>   		return;
>   	}
>   
>   	fd = fileno(file);
>   	if (fd < 0) {
> -		ksft_test_result_fail("fileno() failed\n");
> +		ksft_test_result_fail("fileno() failed (%d)\n", errno);
>   		goto close;
>   	}
>   
> @@ -290,12 +290,12 @@ static void run_with_local_tmpfile(test_fn fn, const char *desc)
>   
>   	fd = mkstemp(filename);
>   	if (fd < 0) {
> -		ksft_test_result_fail("mkstemp() failed\n");
> +		ksft_test_result_fail("mkstemp() failed (%d)\n", errno);
>   		return;
>   	}
>   
>   	if (unlink(filename)) {
> -		ksft_test_result_fail("unlink() failed\n");
> +		ksft_test_result_fail("unlink() failed (%d)\n", errno);
>   		goto close;
>   	}
>   
> @@ -317,7 +317,7 @@ static void run_with_memfd_hugetlb(test_fn fn, const char *desc,
>   
>   	fd = memfd_create("test", flags);
>   	if (fd < 0) {
> -		ksft_test_result_skip("memfd_create() failed\n");
> +		ksft_test_result_skip("memfd_create() failed (%d)\n", errno);
>   		return;
>   	}
>