This case is quit simple by using madvise(MADV_PAGEOUT), but for verifying
the memory size of being swaped, we need to setup the memcg and attach test
process to this memcg before perform the test.

Signed-off-by: Yongting Lin <linyongting@bytedance.com>
---
 tools/testing/selftests/mshare/Makefile |  2 +-
 tools/testing/selftests/mshare/memory.c | 71 +++++++++++++++++++++++++
 2 files changed, 72 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/mshare/memory.c

diff --git a/tools/testing/selftests/mshare/Makefile b/tools/testing/selftests/mshare/Makefile
index 651658d091c5..b0418b8c30f2 100644
--- a/tools/testing/selftests/mshare/Makefile
+++ b/tools/testing/selftests/mshare/Makefile
@@ -2,6 +2,6 @@
 
 CFLAGS = $(KHDR_INCLUDES) -Wall -g -O2
 
-TEST_GEN_PROGS := basic
+TEST_GEN_PROGS := basic memory
 
 include ../lib.mk
diff --git a/tools/testing/selftests/mshare/memory.c b/tools/testing/selftests/mshare/memory.c
new file mode 100644
index 000000000000..7754c0e33506
--- /dev/null
+++ b/tools/testing/selftests/mshare/memory.c
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/mman.h>
+
+#include "../kselftest_harness.h"
+#include "util.c"
+
+#define GB(x) ((x) * (1UL << 30))
+
+FIXTURE(memory)
+{
+	char filename[128];
+	int fd;
+
+	char cgroup[128];
+
+	void *addr;
+	size_t allocate_size;
+};
+
+FIXTURE_SETUP(memory)
+{
+	ASSERT_NE(create_mshare_test_cgroup(self->cgroup, sizeof(self->cgroup)), -1);
+
+	attach_to_cgroup(self->cgroup);
+
+	self->allocate_size = mshare_get_info();
+	self->fd = create_mshare_file(self->filename, sizeof(self->filename));
+	ASSERT_NE(self->fd, -1);
+	ASSERT_NE(ftruncate(self->fd, self->allocate_size), -1);
+
+	ASSERT_NE(mshare_ioctl_mapping(self->fd, self->allocate_size,
+				MAP_ANONYMOUS | MAP_SHARED | MAP_FIXED),
+			-1);
+	self->addr = mmap(NULL, self->allocate_size, PROT_READ | PROT_WRITE,
+						MAP_SHARED, self->fd, 0);
+	ASSERT_NE(self->addr, MAP_FAILED);
+}
+
+FIXTURE_TEARDOWN(memory)
+{
+	ASSERT_NE(munmap(self->addr, self->allocate_size), -1);
+	close(self->fd);
+
+	ASSERT_NE(unlink(self->filename), -1);
+	dettach_from_cgroup(self->cgroup);
+
+	ASSERT_NE(remove_cgroup(self->cgroup), -1);
+}
+
+TEST_F(memory, swap)
+{
+	size_t swap_size;
+
+	/* touch 1G memory */
+	memset(self->addr, 0x01, GB(1));
+
+	/* force to reclaim the memory of mshare */
+	ASSERT_NE(madvise(self->addr, GB(1), MADV_PAGEOUT), -1);
+
+	swap_size = read_swap_from_cgroup(self->cgroup);
+	ASSERT_NE(swap_size, -1);
+
+	/* convert to bytes */
+	swap_size *= 4096;
+
+	/* allow an error of 10% */
+	ASSERT_GT(swap_size, GB(1) * 9 / 10);
+}
+
+TEST_HARNESS_MAIN
-- 
2.20.1