[LTP] [PATCH v1] munlockall: add test case that verifies memory has been unlocked

[Dennis Brendel]

Adding a munlockall() test case that checks if it has the desired effect,
i.e. after calling munlockall() no more memory is locked.

---
 .../kernel/syscalls/munlockall/munlockall02.c | 55 +++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 testcases/kernel/syscalls/munlockall/munlockall02.c

diff --git a/testcases/kernel/syscalls/munlockall/munlockall02.c b/testcases/kernel/syscalls/munlockall/munlockall02.c
new file mode 100644
index 000000000..53d64d47e
--- /dev/null
+++ b/testcases/kernel/syscalls/munlockall/munlockall02.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* 
+ * Copyright Red Hat
+ * Author: Dennis Brendel <dbrendel@redhat.com>
+ */
+
+/*
+ * [Description]
+ *
+ * Verify that munlockall(2) unlocks all previously locked memory
+ */
+
+#include <sys/mman.h>
+
+#include "tst_test.h"
+
+static void verify_munlockall(void)
+{
+    unsigned long int size = 0;
+
+    SAFE_FILE_LINES_SCANF("/proc/self/status", "VmLck: %ld", &size);
+
+    if (size != 0UL) {
+        tst_res(TFAIL, "Locked memory after init should be 0 "
+                       "but is %ld", size);
+    }
+
+    if (mlockall(MCL_CURRENT | MCL_FUTURE) != 0) {
+        tst_res(TFAIL, "Could not lock memory using mlockall()");
+    }
+
+    SAFE_FILE_LINES_SCANF("/proc/self/status", "VmLck: %ld", &size);
+
+    if (size == 0UL) {
+        tst_res(TFAIL, "Locked memory after mlockall() should be greater "
+                       "than 0, but is %ld", size);
+    }
+
+    if (munlockall() != 0) {
+        tst_res(TFAIL, "Could not unlock memory using munlockall()");
+    }
+
+    SAFE_FILE_LINES_SCANF("/proc/self/status", "VmLck: %ld", &size);
+
+    if (size != 0UL) {
+        tst_res(TFAIL, "Locked memory after munlockall() should be 0 "
+                       "but is %ld", size);
+    } else {
+        tst_res(TPASS, "Test passed");
+    }
+}
+
+static struct tst_test test = {
+    .test_all = verify_munlockall,
+};
-- 
2.44.0