Re: [PATCH v5 03/10] selftests/mm: test splitting file-backed THP to any lower order.

[Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>]

On 2025/1/17 05:10, Zi Yan wrote:
> Now split_huge_page*() supports shmem THP split to any lower order.
> Test it.
>
> The test now reads file content out after split to check if the split
> corrupts the file data.
>
> Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>

LGTM.
Reviewed-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>
Tested-by: Baolin Wang <baolin.wang@xxxxxxxxxxxxxxxxx>

> ---
>   .../selftests/mm/split_huge_page_test.c       | 30 ++++++++++++++-----
>   1 file changed, 23 insertions(+), 7 deletions(-)
>
> diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
> index eccaa347140b..766c1f3a1d78 100644
> --- a/tools/testing/selftests/mm/split_huge_page_test.c
> +++ b/tools/testing/selftests/mm/split_huge_page_test.c
> @@ -261,14 +261,16 @@ void split_pte_mapped_thp(void)
>   	close(kpageflags_fd);
>   }
>   
> -void split_file_backed_thp(void)
> +void split_file_backed_thp(int order)
>   {
>   	int status;
>   	int fd, shmem_sysctl_fd;
>   	ssize_t num_written, num_read;
>   	char tmpfs_template[] = "/tmp/thp_split_XXXXXX";
>   	const char *tmpfs_loc = mkdtemp(tmpfs_template);
> -	char testfile[INPUT_MAX], sysctl_buf[INPUT_MAX] = {0};
> +	char testfile[INPUT_MAX];
> +	char sysctl_buf[INPUT_MAX] = {0};
> +	char file_buf[INPUT_MAX] = {0};
>   	uint64_t pgoff_start = 0, pgoff_end = 1024;
>   	const char *shmem_sysctl = "/sys/kernel/mm/transparent_hugepage/shmem_enabled";
>   	char *opt1, *opt2;
> @@ -314,7 +316,7 @@ void split_file_backed_thp(void)
>   		ksft_exit_fail_msg("Fail to create file-backed THP split testing file\n");
>   	}
>   
> -	fd = open(testfile, O_CREAT|O_WRONLY, 0664);
> +	fd = open(testfile, O_CREAT|O_RDWR, 0664);
>   	if (fd == -1) {
>   		ksft_perror("Cannot open testing file");
>   		goto cleanup;
> @@ -322,7 +324,6 @@ void split_file_backed_thp(void)
>   
>   	/* write something to the file, so a file-backed THP can be allocated */
>   	num_written = write(fd, tmpfs_loc, strlen(tmpfs_loc) + 1);
> -	close(fd);
>   
>   	if (num_written < 1) {
>   		ksft_perror("Fail to write data to testing file");
> @@ -330,8 +331,22 @@ void split_file_backed_thp(void)
>   	}
>   
>   	/* split the file-backed THP */
> -	write_debugfs(PATH_FMT, testfile, pgoff_start, pgoff_end, 0);
> +	write_debugfs(PATH_FMT, testfile, pgoff_start, pgoff_end, order);
> +
> +	/* check file content after split */
> +	num_read = lseek(fd, 0, SEEK_SET);
> +	if (num_read == -1) {
> +		ksft_perror("Cannot lseek file");
> +		goto cleanup;
> +	}
>   
> +	num_read = read(fd, file_buf, num_written);
> +	if (num_read < 1 || strncmp(file_buf, tmpfs_loc, num_read)) {
> +		ksft_print_msg("File content changed, origin: %s, now: %s\n", tmpfs_loc, file_buf);
> +		goto cleanup;
> +	}
> +
> +	close(fd);
>   	status = unlink(testfile);
>   	if (status) {
>   		ksft_perror("Cannot remove testing file");
> @@ -520,7 +535,7 @@ int main(int argc, char **argv)
>   	if (argc > 1)
>   		optional_xfs_path = argv[1];
>   
> -	ksft_set_plan(1+8+2+9);
> +	ksft_set_plan(1+8+1+9+9);
>   
>   	pagesize = getpagesize();
>   	pageshift = ffs(pagesize) - 1;
> @@ -537,7 +552,8 @@ int main(int argc, char **argv)
>   			split_pmd_thp_to_order(i);
>   
>   	split_pte_mapped_thp();
> -	split_file_backed_thp();
> +	for (i = 0; i < 9; i++)
> +		split_file_backed_thp(i);
>   
>   	created_tmp = prepare_thp_fs(optional_xfs_path, fs_loc_template,
>   			&fs_loc);