[PATCH] selftests: hugetlb_dio: Fixup Check for initial conditions to skip in the start

[Donet Tom <donettom@linux.ibm.com>]

This test verifies that a hugepage, used as a user buffer for
DIO operations, is correctly freed upon unmapping. To test this,
we read the count of free hugepages before and after the mmap,
DIO, and munmap operations, then check if the free hugepage count
is the same.

Reading free hugepages before the test was removed by commit
0268d4579901 ('selftests: hugetlb_dio: check for initial conditions
to skip at the start'), causing the test to always fail.

This patch adds back reading the free hugepages before starting
the test. With this patch, the tests are now passing.

Test Results without this patch

./tools/testing/selftests/mm/hugetlb_dio
TAP version 13
1..4
 # No. Free pages before allocation : 0
 # No. Free pages after munmap : 100
not ok 1 : Huge pages not freed!
 # No. Free pages before allocation : 0
 # No. Free pages after munmap : 100
not ok 2 : Huge pages not freed!
 # No. Free pages before allocation : 0
 # No. Free pages after munmap : 100
not ok 3 : Huge pages not freed!
 # No. Free pages before allocation : 0
 # No. Free pages after munmap : 100
not ok 4 : Huge pages not freed!
 # Totals: pass:0 fail:4 xfail:0 xpass:0 skip:0 error:0

Test results with this patch.

./tools/testing/selftests/mm/hugetlb_dio
TAP version 13
1..4
 # No. Free pages before allocation : 0
 # No. Free pages after munmap : 100
not ok 1 : Huge pages not freed!
 # No. Free pages before allocation : 0
 # No. Free pages after munmap : 100
not ok 2 : Huge pages not freed!
 # No. Free pages before allocation : 0
 # No. Free pages after munmap : 100
not ok 3 : Huge pages not freed!
 # No. Free pages before allocation : 0
 # No. Free pages after munmap : 100
not ok 4 : Huge pages not freed!
 # Totals: pass:0 fail:4 xfail:0 xpass:0 skip:0 error:0

Fixes: 0268d4579901 ("selftests: hugetlb_dio: check for initial conditions to skip in the start")
Signed-off-by: Donet Tom <donettom@linux.ibm.com>
---
 tools/testing/selftests/mm/hugetlb_dio.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/tools/testing/selftests/mm/hugetlb_dio.c b/tools/testing/selftests/mm/hugetlb_dio.c
index 60001c142ce9..432d5af15e66 100644
--- a/tools/testing/selftests/mm/hugetlb_dio.c
+++ b/tools/testing/selftests/mm/hugetlb_dio.c
@@ -44,6 +44,13 @@ void run_dio_using_hugetlb(unsigned int start_off, unsigned int end_off)
 	if (fd < 0)
 		ksft_exit_fail_perror("Error opening file\n");
 
+	/* Get the free huge pages before allocation */
+	free_hpage_b = get_free_hugepages();
+	if (free_hpage_b == 0) {
+		close(fd);
+		ksft_exit_skip("No free hugepage, exiting!\n");
+	}
+
 	/* Allocate a hugetlb page */
 	orig_buffer = mmap(NULL, h_pagesize, mmap_prot, mmap_flags, -1, 0);
 	if (orig_buffer == MAP_FAILED) {
-- 
2.43.5