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

Implement a kunit test for the core of address range DAMOS filter
handling, namely __damos_filter_out().  The test especially focus on
regions that overlap with given filter's target address range.

Link: https://lkml.kernel.org/r/20230802214312.110532-4-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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

mm/damon/core-test.h

@@ -353,6 +353,66 @@ static void damos_test_new_filter(struct kunit *test)
 	damos_destroy_filter(filter);
 }
 
+static void damos_test_filter_out(struct kunit *test)
+{
+	struct damon_target *t;
+	struct damon_region *r, *r2;
+	struct damos_filter *f;
+
+	f = damos_new_filter(DAMOS_FILTER_TYPE_ADDR, true);
+	f->addr_range = (struct damon_addr_range){
+		.start = DAMON_MIN_REGION * 2, .end = DAMON_MIN_REGION * 6};
+
+	t = damon_new_target();
+	r = damon_new_region(DAMON_MIN_REGION * 3, DAMON_MIN_REGION * 5);
+	damon_add_region(r, t);
+
+	/* region in the range */
+	KUNIT_EXPECT_TRUE(test, __damos_filter_out(NULL, t, r, f));
+	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1);
+
+	/* region before the range */
+	r->ar.start = DAMON_MIN_REGION * 1;
+	r->ar.end = DAMON_MIN_REGION * 2;
+	KUNIT_EXPECT_FALSE(test, __damos_filter_out(NULL, t, r, f));
+	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1);
+
+	/* region after the range */
+	r->ar.start = DAMON_MIN_REGION * 6;
+	r->ar.end = DAMON_MIN_REGION * 8;
+	KUNIT_EXPECT_FALSE(test, __damos_filter_out(NULL, t, r, f));
+	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1);
+
+	/* region started before the range */
+	r->ar.start = DAMON_MIN_REGION * 1;
+	r->ar.end = DAMON_MIN_REGION * 4;
+	KUNIT_EXPECT_FALSE(test, __damos_filter_out(NULL, t, r, f));
+	/* filter should have split the region */
+	KUNIT_EXPECT_EQ(test, r->ar.start, DAMON_MIN_REGION * 1);
+	KUNIT_EXPECT_EQ(test, r->ar.end, DAMON_MIN_REGION * 2);
+	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 2);
+	r2 = damon_next_region(r);
+	KUNIT_EXPECT_EQ(test, r2->ar.start, DAMON_MIN_REGION * 2);
+	KUNIT_EXPECT_EQ(test, r2->ar.end, DAMON_MIN_REGION * 4);
+	damon_destroy_region(r2, t);
+
+	/* region started in the range */
+	r->ar.start = DAMON_MIN_REGION * 2;
+	r->ar.end = DAMON_MIN_REGION * 8;
+	KUNIT_EXPECT_TRUE(test, __damos_filter_out(NULL, t, r, f));
+	/* filter should have split the region */
+	KUNIT_EXPECT_EQ(test, r->ar.start, DAMON_MIN_REGION * 2);
+	KUNIT_EXPECT_EQ(test, r->ar.end, DAMON_MIN_REGION * 6);
+	KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 2);
+	r2 = damon_next_region(r);
+	KUNIT_EXPECT_EQ(test, r2->ar.start, DAMON_MIN_REGION * 6);
+	KUNIT_EXPECT_EQ(test, r2->ar.end, DAMON_MIN_REGION * 8);
+	damon_destroy_region(r2, t);
+
+	damon_free_target(t);
+	damos_free_filter(f);
+}
+
 static struct kunit_case damon_test_cases[] = {
 	KUNIT_CASE(damon_test_target),
 	KUNIT_CASE(damon_test_regions),
@@ -366,6 +426,7 @@ static struct kunit_case damon_test_cases[] = {
 	KUNIT_CASE(damon_test_update_monitoring_result),
 	KUNIT_CASE(damon_test_set_attrs),
 	KUNIT_CASE(damos_test_new_filter),
+	KUNIT_CASE(damos_test_filter_out),
 	{},
 };