The current test_memcontrol test fault in memory by write a value
to the start of a page based on the default value of 4k page size.
Micro-optimize it by using the actual system page size to do the
iteration.

Reviewed-by: Li Wang <liwang@redhat.com>
Signed-off-by: Waiman Long <longman@redhat.com>
---
 tools/testing/selftests/cgroup/test_memcontrol.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c b/tools/testing/selftests/cgroup/test_memcontrol.c
index a25eb097b31c..babbfad10aaf 100644
--- a/tools/testing/selftests/cgroup/test_memcontrol.c
+++ b/tools/testing/selftests/cgroup/test_memcontrol.c
@@ -25,6 +25,7 @@
 
 static bool has_localevents;
 static bool has_recursiveprot;
+static int page_size;
 
 int get_temp_fd(void)
 {
@@ -60,7 +61,7 @@ int alloc_anon(const char *cgroup, void *arg)
 	char *buf, *ptr;
 
 	buf = malloc(size);
-	for (ptr = buf; ptr < buf + size; ptr += PAGE_SIZE)
+	for (ptr = buf; ptr < buf + size; ptr += page_size)
 		*ptr = 0;
 
 	free(buf);
@@ -183,7 +184,7 @@ static int alloc_anon_50M_check(const char *cgroup, void *arg)
 		return -1;
 	}
 
-	for (ptr = buf; ptr < buf + size; ptr += PAGE_SIZE)
+	for (ptr = buf; ptr < buf + size; ptr += page_size)
 		*ptr = 0;
 
 	current = cg_read_long(cgroup, "memory.current");
@@ -413,7 +414,7 @@ static int alloc_anon_noexit(const char *cgroup, void *arg)
 		return -1;
 	}
 
-	for (ptr = buf; ptr < buf + size; ptr += PAGE_SIZE)
+	for (ptr = buf; ptr < buf + size; ptr += page_size)
 		*ptr = 0;
 
 	while (getppid() == ppid)
@@ -999,7 +1000,7 @@ static int alloc_anon_50M_check_swap(const char *cgroup, void *arg)
 		return -1;
 	}
 
-	for (ptr = buf; ptr < buf + size; ptr += PAGE_SIZE)
+	for (ptr = buf; ptr < buf + size; ptr += page_size)
 		*ptr = 0;
 
 	mem_current = cg_read_long(cgroup, "memory.current");
@@ -1679,6 +1680,10 @@ int main(int argc, char **argv)
 	char root[PATH_MAX];
 	int i, proc_status;
 
+	page_size = sysconf(_SC_PAGE_SIZE);
+	if (page_size <= 0)
+		page_size = PAGE_SIZE;
+
 	ksft_print_header();
 	ksft_set_plan(ARRAY_SIZE(tests));
 	if (cg_find_unified_root(root, sizeof(root), NULL))
-- 
2.53.0