[LTP] [PATCH v3] controllers/memcg: Add testcase for kmem_limit_in_bytes of memory cgroup

[Zhao Gongyi]

Add memory cgroup testcase for checking that kmem overflow is controlled
by kmem.limit_in_bytes.

Signed-off-by: Zhao Gongyi <zhaogongyi@huawei.com>
---
v2->v3: remove the calling of tst_res/tst_brk in test process to avoid
kmem allocation
---
 runtest/controllers                           |  1 +
 testcases/kernel/controllers/memcg/.gitignore |  1 +
 .../functional/memcg_kmem_limit_in_bytes.c    | 76 +++++++++++++++++++
 3 files changed, 78 insertions(+)
 create mode 100644 testcases/kernel/controllers/memcg/functional/memcg_kmem_limit_in_bytes.c

diff --git a/runtest/controllers b/runtest/controllers
index e3d0243f1..f13a112c7 100644
--- a/runtest/controllers
+++ b/runtest/controllers
@@ -15,6 +15,7 @@ memcg_use_hierarchy	memcg_use_hierarchy_test.sh
 memcg_usage_in_bytes	memcg_usage_in_bytes_test.sh
 memcg_stress		memcg_stress_test.sh
 memcg_control		memcg_control_test.sh
+memcg_kmem_limit_in_bytes memcg_kmem_limit_in_bytes

 cgroup_fj_function_debug cgroup_fj_function.sh debug
 cgroup_fj_function_cpuset cgroup_fj_function.sh cpuset
diff --git a/testcases/kernel/controllers/memcg/.gitignore b/testcases/kernel/controllers/memcg/.gitignore
index c0b6d0714..dce8412de 100644
--- a/testcases/kernel/controllers/memcg/.gitignore
+++ b/testcases/kernel/controllers/memcg/.gitignore
@@ -1,5 +1,6 @@
 /control/mem_process
 /functional/memcg_process
+/functional/memcg_kmem_limit_in_bytes
 /regression/memcg_test_1
 /regression/memcg_test_2
 /regression/memcg_test_3
diff --git a/testcases/kernel/controllers/memcg/functional/memcg_kmem_limit_in_bytes.c b/testcases/kernel/controllers/memcg/functional/memcg_kmem_limit_in_bytes.c
new file mode 100644
index 000000000..4521d299c
--- /dev/null
+++ b/testcases/kernel/controllers/memcg/functional/memcg_kmem_limit_in_bytes.c
@@ -0,0 +1,76 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (c) 2021 HUAWEI LIMITED
+ * Author: Zhao Gongyi <zhaogongyi@huawei.com>
+ */
+
+/*\
+ * [Description]
+ * Check that kmem overflow is controlled by kmem.limit_in_bytes.
+ *
+ * [Algorithm]
+ * 1) mount memory cgroup
+ * 2) set 0 to memory.kmem.limit_in_bytes
+ * 3) set test process id to cgroup.procs
+ * 4) fork in test process to trig kmem overflow
+ */
+
+#include <sys/wait.h>
+#include "tst_test.h"
+
+#define MNT_POINT "memcg"
+#define TESTDIR "memcg/ltpmemcg"
+#define CGROUP_PROCS "memcg/ltpmemcg/cgroup.procs"
+#define KMEM_LIMIT_IN_BYTES "memcg/ltpmemcg/memory.kmem.limit_in_bytes"
+
+static void cleanup(void)
+{
+	SAFE_RMDIR(TESTDIR);
+	SAFE_UMOUNT(MNT_POINT);
+	SAFE_RMDIR(MNT_POINT);
+}
+
+static void setup(void)
+{
+	SAFE_MKDIR(MNT_POINT, 0755);
+	SAFE_MOUNT("memcg", MNT_POINT, "cgroup", 0, "memory");
+	SAFE_MKDIR(TESTDIR, 0755);
+}
+
+static void run(void)
+{
+	pid_t pid;
+	int st;
+
+	pid = SAFE_FORK();
+	if (!pid) {
+		SAFE_FILE_PRINTF(KMEM_LIMIT_IN_BYTES, "%d", 0);
+		SAFE_FILE_PRINTF(CGROUP_PROCS, "%d", getpid());
+
+		TEST(fork());
+		if (TST_RET == -1 && TST_ERR == ENOMEM)
+			_exit(TPASS);
+		else
+			_exit(TFAIL);
+	} else {
+		SAFE_WAIT(&st);
+		if (WIFEXITED(st))
+			if (!WEXITSTATUS(st)) {
+				tst_res(TPASS, "kmem alloc is controled "
+					"by memory.kmem.limit_in_bytes");
+				return;
+			}
+
+		tst_res(TFAIL,"kmem alloc is not controled "
+			"by memory.kmem.limit_in_bytes");
+	}
+}
+
+static struct tst_test test = {
+	.needs_root = 1,
+	.needs_tmpdir = 1,
+	.forks_child = 1,
+	.setup = setup,
+	.test_all = run,
+	.cleanup = cleanup,
+};
--
2.17.1