Kernel already supports splitting a folio to any lower order. Test it.

Signed-off-by: Zi Yan <ziy@nvidia.com>
---
 tools/testing/selftests/mm/split_huge_page_test.c | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/tools/testing/selftests/mm/split_huge_page_test.c b/tools/testing/selftests/mm/split_huge_page_test.c
index cd74ea9b1295..5bb159ebc83d 100644
--- a/tools/testing/selftests/mm/split_huge_page_test.c
+++ b/tools/testing/selftests/mm/split_huge_page_test.c
@@ -144,7 +144,7 @@ void split_pmd_zero_pages(void)
 	free(one_page);
 }
 
-void split_pmd_thp(void)
+void split_pmd_thp_to_order(int order)
 {
 	char *one_page;
 	size_t len = 4 * pmd_pagesize;
@@ -164,7 +164,7 @@ void split_pmd_thp(void)
 
 	/* split all THPs */
 	write_debugfs(PID_FMT, getpid(), (uint64_t)one_page,
-		(uint64_t)one_page + len, 0);
+		(uint64_t)one_page + len, order);
 
 	for (i = 0; i < len; i++)
 		if (one_page[i] != (char)i)
@@ -174,7 +174,7 @@ void split_pmd_thp(void)
 	if (!check_huge_anon(one_page, 0, pmd_pagesize))
 		ksft_exit_fail_msg("Still AnonHugePages not split\n");
 
-	ksft_test_result_pass("Split huge pages successful\n");
+	ksft_test_result_pass("Split huge pages to order %d successful\n", order);
 	free(one_page);
 }
 
@@ -481,7 +481,7 @@ int main(int argc, char **argv)
 	if (argc > 1)
 		optional_xfs_path = argv[1];
 
-	ksft_set_plan(4+9);
+	ksft_set_plan(1+9+2+9);
 
 	pagesize = getpagesize();
 	pageshift = ffs(pagesize) - 1;
@@ -492,7 +492,10 @@ int main(int argc, char **argv)
 	fd_size = 2 * pmd_pagesize;
 
 	split_pmd_zero_pages();
-	split_pmd_thp();
+
+	for (i = 0; i < 9; i++)
+		split_pmd_thp_to_order(i);
+
 	split_pte_mapped_thp();
 	split_file_backed_thp();
 
-- 
2.45.2