selftests: hugetlb_dio: fixup check for initial conditions to skip in the start

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 : 100
# No. Free pages after munmap : 100
ok 1 : Huge pages freed successfully !
# No. Free pages before allocation : 100
# No. Free pages after munmap : 100
ok 2 : Huge pages freed successfully !
# No. Free pages before allocation : 100
# No. Free pages after munmap : 100
ok 3 : Huge pages freed successfully !
# No. Free pages before allocation : 100
# No. Free pages after munmap : 100
ok 4 : Huge pages freed successfully !

# Totals: pass:4 fail:0 xfail:0 xpass:0 skip:0 error:0

Link: https://lkml.kernel.org/r/20241110064903.23626-1-donettom@linux.ibm.com
Fixes: 0268d4579901 ("selftests: hugetlb_dio: check for initial conditions to skip in the start")
Signed-off-by: Donet Tom <donettom@linux.ibm.com>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/tools/testing/selftests/mm/hugetlb_dio.c b/tools/testing/selftests/mm/hugetlb_dio.c
index 60001c142ce9984607a8d5c23ae4a823d0b10891..432d5af15e66b7d6cac0273fb244d6696d7c9ddc 100644 (file)
--- 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) {