As discussed in [1], damon_va_evenly_split_region() is called to
size-evenly split a region into 'nr_pieces' small regions,
when nr_pieces == 1, no actual split is required. Check that case
for better code readability and add a simple kunit testcase.
[1] https://lore.kernel.org/all/20241021163316.12443-1-sj@kernel.org/
Signed-off-by: Zheng Yejian <zhengyejian@huaweicloud.com>
---
mm/damon/tests/vaddr-kunit.h | 1 +
mm/damon/vaddr.c | 3 +++
2 files changed, 4 insertions(+)
diff --git a/mm/damon/tests/vaddr-kunit.h b/mm/damon/tests/vaddr-kunit.h
index a149e354bb26..b9a03e4e29e5 100644
--- a/mm/damon/tests/vaddr-kunit.h
+++ b/mm/damon/tests/vaddr-kunit.h
@@ -300,6 +300,7 @@ static void damon_test_split_evenly(struct kunit *test)
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_succ(test, 4, 6, 1);
damon_test_split_evenly_succ(test, 0, 3, 2);
damon_test_split_evenly_fail(test, 5, 6, 2);
}
diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index dba3b2f4d758..25db0a582c27 100644
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -72,6 +72,9 @@ static int damon_va_evenly_split_region(struct damon_target *t,
if (!r || !nr_pieces)
return -EINVAL;
+ if (nr_pieces == 1)
+ return 0;
+
orig_end = r->ar.end;
sz_orig = damon_sz_region(r);
sz_piece = ALIGN_DOWN(sz_orig / nr_pieces, DAMON_MIN_REGION);
--
2.25.1