mm/damon/core-test: test damon_set_regions

Preceding commit fixes a bug in 'damon_set_regions()', which allows holes
in the new monitoring target ranges.  This commit adds a kunit test case
for the problem to avoid any regression.

Link: https://lkml.kernel.org/r/20220909202901.57977-4-sj@kernel.orgSigned-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Yun Levi <ppbuk5246@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon/core-test.h

@@ -267,6 +267,28 @@ static void damon_test_ops_registration(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, damon_register_ops(&ops), -EINVAL);
 }
 
+static void damon_test_set_regions(struct kunit *test)
+{
+	struct damon_target *t = damon_new_target();
+	struct damon_region *r1 = damon_new_region(4, 16);
+	struct damon_region *r2 = damon_new_region(24, 32);
+	struct damon_addr_range range = {.start = 8, .end = 28};
+	unsigned long expects[] = {8, 16, 16, 24, 24, 28};
+	int expect_idx = 0;
+	struct damon_region *r;
+
+	damon_add_region(r1, t);
+	damon_add_region(r2, t);
+	damon_set_regions(t, &range, 1);
+
+	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 3);
+	damon_for_each_region(r, t) {
+		KUNIT_EXPECT_EQ(test, r->ar.start, expects[expect_idx++]);
+		KUNIT_EXPECT_EQ(test, r->ar.end, expects[expect_idx++]);
+	}
+	damon_destroy_target(t);
+}
+
 static struct kunit_case damon_test_cases[] = {
 	KUNIT_CASE(damon_test_target),
 	KUNIT_CASE(damon_test_regions),
@@ -276,6 +298,7 @@ static struct kunit_case damon_test_cases[] = {
 	KUNIT_CASE(damon_test_merge_regions_of),
 	KUNIT_CASE(damon_test_split_regions_of),
 	KUNIT_CASE(damon_test_ops_registration),
+	KUNIT_CASE(damon_test_set_regions),
 	{},
 };