Re: [PATCH v1 3/3] selftests/mm: gup_longterm: add liburing tests

[Lorenzo Stoakes <lstoakes@gmail.com>]

On Fri, May 19, 2023 at 12:27:23PM +0200, David Hildenbrand wrote:
> Similar to the COW selftests, also use io_uring fixed buffers to test
> if long-term page pinning works as expected.
>
> Signed-off-by: David Hildenbrand <david@redhat.com>
> ---
>  tools/testing/selftests/mm/gup_longterm.c | 73 +++++++++++++++++++++++
>  1 file changed, 73 insertions(+)
>
> diff --git a/tools/testing/selftests/mm/gup_longterm.c b/tools/testing/selftests/mm/gup_longterm.c
> index 44a3617fd423..d33d3e68ffab 100644
> --- a/tools/testing/selftests/mm/gup_longterm.c
> +++ b/tools/testing/selftests/mm/gup_longterm.c
> @@ -22,6 +22,9 @@
>  #include <linux/memfd.h>
>
>  #include "local_config.h"
> +#ifdef LOCAL_CONFIG_HAVE_LIBURING
> +#include <liburing.h>
> +#endif /* LOCAL_CONFIG_HAVE_LIBURING */
>
>  #include "../../../../mm/gup_test.h"
>  #include "../kselftest.h"
> @@ -80,6 +83,9 @@ enum test_type {
>  	TEST_TYPE_RO_FAST,
>  	TEST_TYPE_RW,
>  	TEST_TYPE_RW_FAST,
> +#ifdef LOCAL_CONFIG_HAVE_LIBURING
> +	TEST_TYPE_IOURING,
> +#endif /* LOCAL_CONFIG_HAVE_LIBURING */
>  };
>
>  static void do_test(int fd, size_t size, enum test_type type, bool shared)
> @@ -173,6 +179,51 @@ static void do_test(int fd, size_t size, enum test_type type, bool shared)
>  		ksft_test_result(should_work, "Should have worked\n");
>  		break;
>  	}
> +#ifdef LOCAL_CONFIG_HAVE_LIBURING
> +	case TEST_TYPE_IOURING: {
> +		struct io_uring ring;
> +		struct iovec iov;
> +
> +		/* io_uring always pins pages writable. */
> +		if (shared && fs_is_unknown(fs_type)) {
> +			ksft_test_result_skip("Unknown filesystem\n");
> +			return;
> +		}
> +		should_work = !shared ||
> +			      fs_supports_writable_longterm_pinning(fs_type);
> +
> +		/* 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");
> +			break;
> +		}
> +		/*
> +		 * Register the range as a fixed buffer. This will FOLL_WRITE |
> +		 * FOLL_PIN | FOLL_LONGTERM the range.
> +		 */
> +		iov.iov_base = mem;
> +		iov.iov_len = size;
> +		ret = io_uring_register_buffers(&ring, &iov, 1);
> +		/* Only new kernels return EFAULT. */
> +		if (ret && (errno == ENOSPC || errno == EOPNOTSUPP ||
> +			    errno == EFAULT)) {
> +			ksft_test_result(!should_work, "Should have failed\n");
> +		} else if (ret) {
> +			/*
> +			 * We might just lack support or have insufficient
> +			 * MEMLOCK limits.
> +			 */
> +			ksft_test_result_skip("io_uring_register_buffers() failed\n");
> +		} else {
> +			ksft_test_result(should_work, "Should have worked\n");
> +			io_uring_unregister_buffers(&ring);
> +		}
> +
> +		io_uring_queue_exit(&ring);
> +		break;
> +	}
> +#endif /* LOCAL_CONFIG_HAVE_LIBURING */
>  	default:
>  		assert(false);
>  	}
> @@ -310,6 +361,18 @@ static void test_private_ro_fast_pin(int fd, size_t size)
>  	do_test(fd, size, TEST_TYPE_RO_FAST, false);
>  }
>
> +#ifdef LOCAL_CONFIG_HAVE_LIBURING
> +static void test_shared_iouring(int fd, size_t size)
> +{
> +	do_test(fd, size, TEST_TYPE_IOURING, true);
> +}
> +
> +static void test_private_iouring(int fd, size_t size)
> +{
> +	do_test(fd, size, TEST_TYPE_IOURING, false);
> +}
> +#endif /* LOCAL_CONFIG_HAVE_LIBURING */
> +
>  static const struct test_case test_cases[] = {
>  	{
>  		"R/W longterm GUP pin in MAP_SHARED file mapping",
> @@ -343,6 +406,16 @@ static const struct test_case test_cases[] = {
>  		"R/O longterm GUP-fast pin in MAP_PRIVATE file mapping",
>  		test_private_ro_fast_pin,
>  	},
> +#ifdef LOCAL_CONFIG_HAVE_LIBURING
> +	{
> +		"io_uring fixed buffer with MAP_SHARED file mapping",
> +		test_shared_iouring,
> +	},
> +	{
> +		"io_uring fixed buffer with MAP_PRIVATE file mapping",
> +		test_private_iouring,
> +	},
> +#endif /* LOCAL_CONFIG_HAVE_LIBURING */
>  };
>
>  static void run_test_case(struct test_case const *test_case)
> --
> 2.40.1
>

All good,

Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>