selftests: vm: return Kselftest Skip code for skipped tests

When vm test is skipped because of unmet dependencies and/or unsupported
configuration, it exits with error which is treated as a fail by the
Kselftest framework. This leads to false negative result even when the
test could not be run.

Change it to return kselftest skip code when a test gets skipped to
clearly report that the test could not be run.

Kselftest framework SKIP code is 4 and the framework prints appropriate
messages to indicate that the test is skipped.

Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>
Acked-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Shuah Khan (Samsung OSG) <shuah@kernel.org>
diff --git a/tools/testing/selftests/vm/mlock2-tests.c b/tools/testing/selftests/vm/mlock2-tests.c
index 4997b92..637b6d0 100644
--- a/tools/testing/selftests/vm/mlock2-tests.c
+++ b/tools/testing/selftests/vm/mlock2-tests.c
@@ -9,6 +9,8 @@
 #include <stdbool.h>
 #include "mlock2.h"
 
+#include "../kselftest.h"
+
 struct vm_boundaries {
 	unsigned long start;
 	unsigned long end;
@@ -303,7 +305,7 @@ static int test_mlock_lock()
 	if (mlock2_(map, 2 * page_size, 0)) {
 		if (errno == ENOSYS) {
 			printf("Cannot call new mlock family, skipping test\n");
-			_exit(0);
+			_exit(KSFT_SKIP);
 		}
 		perror("mlock2(0)");
 		goto unmap;
@@ -412,7 +414,7 @@ static int test_mlock_onfault()
 	if (mlock2_(map, 2 * page_size, MLOCK_ONFAULT)) {
 		if (errno == ENOSYS) {
 			printf("Cannot call new mlock family, skipping test\n");
-			_exit(0);
+			_exit(KSFT_SKIP);
 		}
 		perror("mlock2(MLOCK_ONFAULT)");
 		goto unmap;
@@ -425,7 +427,7 @@ static int test_mlock_onfault()
 	if (munlock(map, 2 * page_size)) {
 		if (errno == ENOSYS) {
 			printf("Cannot call new mlock family, skipping test\n");
-			_exit(0);
+			_exit(KSFT_SKIP);
 		}
 		perror("munlock()");
 		goto unmap;
@@ -457,7 +459,7 @@ static int test_lock_onfault_of_present()
 	if (mlock2_(map, 2 * page_size, MLOCK_ONFAULT)) {
 		if (errno == ENOSYS) {
 			printf("Cannot call new mlock family, skipping test\n");
-			_exit(0);
+			_exit(KSFT_SKIP);
 		}
 		perror("mlock2(MLOCK_ONFAULT)");
 		goto unmap;
@@ -583,7 +585,7 @@ static int test_vma_management(bool call_mlock)
 	if (call_mlock && mlock2_(map, 3 * page_size, MLOCK_ONFAULT)) {
 		if (errno == ENOSYS) {
 			printf("Cannot call new mlock family, skipping test\n");
-			_exit(0);
+			_exit(KSFT_SKIP);
 		}
 		perror("mlock(ONFAULT)\n");
 		goto out;