[PATCH 2/2] selftests/mm: add tests for splitting pmd THPs to all lower orders.

[Zi Yan]

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

Signed-off-by: Zi Yan <z...@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 128004308233..3d3bc40a268b 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