[PATCH 41/53] selftests/mm: hugetlb-soft-online: add setup of HugeTLB pages

Mike Rapoport
2026-04-06T14:21:43Z

hugetlb-soft-online test uses open coded access to /proc to determine
availability of huge pages and fails if there are no enough free huget
pages..

Replace open coded access to /proc with hugepage helpers and add setup
of HugeTLB pages to the test and make sure that the original settings
are restored on the test exit.

Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
.../selftests/mm/hugetlb-soft-offline.c | 45 ++++---------------
1 file changed, 8 insertions(+), 37 deletions(-)

diff --git a/tools/testing/selftests/mm/hugetlb-soft-offline.c b/tools/testing/selftests/mm/hugetlb-soft-offline.c
index a8bc02688085..bc202e4ed2bd 100644
--- a/tools/testing/selftests/mm/hugetlb-soft-offline.c
+++ b/tools/testing/selftests/mm/hugetlb-soft-offline.c
@@ -6,9 +6,7 @@
* - if enable_soft_offline = 1, a hugepage should be dissolved and
* nr_hugepages/free_hugepages should be reduced by 1.
*
- * Before running, make sure more than 2 hugepages of default_hugepagesz
- * are allocated. For example, if /proc/meminfo/Hugepagesize is 2048kB:
- * echo 8 > /sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages
+ * The test allocates 8 default hugepages
*/

#define _GNU_SOURCE
@@ -25,6 +23,7 @@
#include <sys/types.h>

#include "kselftest.h"
+#include "hugepage_settings.h"

#ifndef MADV_SOFT_OFFLINE
#define MADV_SOFT_OFFLINE 101
@@ -100,32 +99,6 @@ static int set_enable_soft_offline(int value)
return 0;
}

-static int read_nr_hugepages(unsigned long hugepage_size,
- unsigned long *nr_hugepages)
-{
- char buffer[256] = {0};
- char cmd[256] = {0};
-
- sprintf(cmd, "cat /sys/kernel/mm/hugepages/hugepages-%ldkB/nr_hugepages",
- hugepage_size);
- FILE *cmdfile = popen(cmd, "r");
-
- if (cmdfile == NULL) {
- ksft_perror(EPREFIX "failed to popen nr_hugepages");
- return -1;
- }
-
- if (!fgets(buffer, sizeof(buffer), cmdfile)) {
- ksft_perror(EPREFIX "failed to read nr_hugepages");
- pclose(cmdfile);
- return -1;
- }
-
- *nr_hugepages = atoll(buffer);
- pclose(cmdfile);
- return 0;
-}
-
static int create_hugetlbfs_file(struct statfs *file_stat)
{
int fd;
@@ -177,20 +150,14 @@ static void test_soft_offline_common(int enable_soft_offline)
ksft_exit_fail_msg("Failed to set enable_soft_offline\n");
}

- if (read_nr_hugepages(hugepagesize_kb, &nr_hugepages_before) != 0) {
- close(fd);
- ksft_exit_fail_msg("Failed to read nr_hugepages\n");
- }
+ nr_hugepages_before = hugetlb_nr_default_pages();

ksft_print_msg("Before MADV_SOFT_OFFLINE nr_hugepages=%ld\n",
nr_hugepages_before);

ret = do_soft_offline(fd, 2 * file_stat.f_bsize, expect_errno);

- if (read_nr_hugepages(hugepagesize_kb, &nr_hugepages_after) != 0) {
- close(fd);
- ksft_exit_fail_msg("Failed to read nr_hugepages\n");
- }
+ nr_hugepages_after = hugetlb_nr_default_pages();

ksft_print_msg("After MADV_SOFT_OFFLINE nr_hugepages=%ld\n",
nr_hugepages_after);
@@ -219,6 +186,10 @@ static void test_soft_offline_common(int enable_soft_offline)
int main(int argc, char **argv)
{
ksft_print_header();
+
+ if (!hugetlb_setup_default(8))
+ ksft_exit_skip("not enough hugetlb pages\n");
+
ksft_set_plan(2);

test_soft_offline_common(1);
--
2.53.0