mm/damon/core-test: add a test for damon_set_attrs()

Commit 5ff6e2f ("mm/damon/core: fix divide error in
damon_nr_accesses_to_accesses_bp()") fixed a bug by adding arguments
validation in damon_set_attrs().  Add a unit test for the added validation
to ensure the bug cannot occur again.

Link: https://lkml.kernel.org/r/20230615183323.87561-1-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: sjp38

mm/damon/core-test.h

@@ -318,6 +318,29 @@ static void damon_test_update_monitoring_result(struct kunit *test)
 	KUNIT_EXPECT_EQ(test, r->age, 20);
 }
 
+static void damon_test_set_attrs(struct kunit *test)
+{
+	struct damon_ctx ctx;
+	struct damon_attrs valid_attrs = {
+		.min_nr_regions = 10, .max_nr_regions = 1000,
+		.sample_interval = 5000, .aggr_interval = 100000,};
+	struct damon_attrs invalid_attrs;
+
+	KUNIT_EXPECT_EQ(test, damon_set_attrs(&ctx, &valid_attrs), 0);
+
+	invalid_attrs = valid_attrs;
+	invalid_attrs.min_nr_regions = 1;
+	KUNIT_EXPECT_EQ(test, damon_set_attrs(&ctx, &invalid_attrs), -EINVAL);
+
+	invalid_attrs = valid_attrs;
+	invalid_attrs.max_nr_regions = 9;
+	KUNIT_EXPECT_EQ(test, damon_set_attrs(&ctx, &invalid_attrs), -EINVAL);
+
+	invalid_attrs = valid_attrs;
+	invalid_attrs.aggr_interval = 4999;
+	KUNIT_EXPECT_EQ(test, damon_set_attrs(&ctx, &invalid_attrs), -EINVAL);
+}
+
 static struct kunit_case damon_test_cases[] = {
 	KUNIT_CASE(damon_test_target),
 	KUNIT_CASE(damon_test_regions),
@@ -329,6 +352,7 @@ static struct kunit_case damon_test_cases[] = {
 	KUNIT_CASE(damon_test_ops_registration),
 	KUNIT_CASE(damon_test_set_regions),
 	KUNIT_CASE(damon_test_update_monitoring_result),
+	KUNIT_CASE(damon_test_set_attrs),
 	{},
 };