new_three_regions, expected, ARRAY_SIZE(expected));
 }
 
-static void damon_test_split_evenly(struct kunit *test)
+static void damon_test_split_evenly_fail(struct kunit *test,
+               unsigned long start, unsigned long end, unsigned int nr_pieces)
 {
-       struct damon_ctx *c = damon_new_ctx();
-       struct damon_target *t;
-       struct damon_region *r;
-       unsigned long i;
-
-       KUNIT_EXPECT_EQ(test, damon_va_evenly_split_region(NULL, NULL, 5),
-                       -EINVAL);
-
-       t = damon_new_target(42);
-       r = damon_new_region(0, 100);
-       KUNIT_EXPECT_EQ(test, damon_va_evenly_split_region(t, r, 0), -EINVAL);
+       struct damon_target *t = damon_new_target(42);
+       struct damon_region *r = damon_new_region(start, end);
 
        damon_add_region(r, t);
-       KUNIT_EXPECT_EQ(test, damon_va_evenly_split_region(t, r, 10), 0);
-       KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 10u);
+       KUNIT_EXPECT_EQ(test,
+                       damon_va_evenly_split_region(t, r, nr_pieces), -EINVAL);
+       KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1u);
 
-       i = 0;
        damon_for_each_region(r, t) {
-               KUNIT_EXPECT_EQ(test, r->ar.start, i++ * 10);
-               KUNIT_EXPECT_EQ(test, r->ar.end, i * 10);
+               KUNIT_EXPECT_EQ(test, r->ar.start, start);
+               KUNIT_EXPECT_EQ(test, r->ar.end, end);
        }
+
        damon_free_target(t);
+}
+
+static void damon_test_split_evenly_succ(struct kunit *test,
+       unsigned long start, unsigned long end, unsigned int nr_pieces)
+{
+       struct damon_target *t = damon_new_target(42);
+       struct damon_region *r = damon_new_region(start, end);
+       unsigned long expected_width = (end - start) / nr_pieces;
+       unsigned long i = 0;
 
-       t = damon_new_target(42);
-       r = damon_new_region(5, 59);
        damon_add_region(r, t);
-       KUNIT_EXPECT_EQ(test, damon_va_evenly_split_region(t, r, 5), 0);
-       KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 5u);
+       KUNIT_EXPECT_EQ(test,
+                       damon_va_evenly_split_region(t, r, nr_pieces), 0);
+       KUNIT_EXPECT_EQ(test, damon_nr_regions(t), nr_pieces);
 
-       i = 0;
        damon_for_each_region(r, t) {
-               if (i == 4)
+               if (i == nr_pieces - 1)
                        break;
-               KUNIT_EXPECT_EQ(test, r->ar.start, 5 + 10 * i++);
-               KUNIT_EXPECT_EQ(test, r->ar.end, 5 + 10 * i);
+               KUNIT_EXPECT_EQ(test,
+                               r->ar.start, start + i++ * expected_width);
+               KUNIT_EXPECT_EQ(test, r->ar.end, start + i * expected_width);
        }
-       KUNIT_EXPECT_EQ(test, r->ar.start, 5 + 10 * i);
-       KUNIT_EXPECT_EQ(test, r->ar.end, 59ul);
+       KUNIT_EXPECT_EQ(test, r->ar.start, start + i * expected_width);
+       KUNIT_EXPECT_EQ(test, r->ar.end, end);
        damon_free_target(t);
+}
 
-       t = damon_new_target(42);
-       r = damon_new_region(5, 6);
-       damon_add_region(r, t);
-       KUNIT_EXPECT_EQ(test, damon_va_evenly_split_region(t, r, 2), -EINVAL);
-       KUNIT_EXPECT_EQ(test, damon_nr_regions(t), 1u);
+static void damon_test_split_evenly(struct kunit *test)
+{
+       struct damon_ctx *c = damon_new_ctx();
+
+       KUNIT_EXPECT_EQ(test, damon_va_evenly_split_region(NULL, NULL, 5),
+                       -EINVAL);
+
+       damon_test_split_evenly_fail(test, 0, 100, 0);
+       damon_test_split_evenly_succ(test, 0, 100, 10);
+       damon_test_split_evenly_succ(test, 5, 59, 5);
+       damon_test_split_evenly_fail(test, 5, 6, 2);
 
-       damon_for_each_region(r, t) {
-               KUNIT_EXPECT_EQ(test, r->ar.start, 5ul);
-               KUNIT_EXPECT_EQ(test, r->ar.end, 6ul);
-       }
-       damon_free_target(t);
        damon_destroy_ctx(c);
 }