[PATCH] mm/damon: validate min_region_size to be power of 2

[Liew Rui Yan <aethernet65535@gmail.com>]

Problem
=======
damon_commit_ctx() checks if 'min_region_sz' is a power of 2. But if it
is not, kdamond will terminate unexpectedly due to the user's invalid
input.

Solution
========
Add the same check to damon_{lru_sort, reclaim}_apply_parameters(), but
return -EINVAL immediately. This is to prevent user's invalid input
causing kdamond to terminate unexpectedly.

Signed-off-by: Liew Rui Yan <aethernet65535@gmail.com>
---
 mm/damon/lru_sort.c | 3 +++
 mm/damon/reclaim.c  | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c
index 554559d72976..205592194efd 100644
--- a/mm/damon/lru_sort.c
+++ b/mm/damon/lru_sort.c
@@ -294,6 +294,9 @@ static int damon_lru_sort_apply_parameters(void)
 	param_ctx->addr_unit = addr_unit;
 	param_ctx->min_region_sz = max(DAMON_MIN_REGION_SZ / addr_unit, 1);
 
+	if (!is_power_of_2(param_ctx->min_region_sz))
+		return -EINVAL;
+
 	if (!damon_lru_sort_mon_attrs.sample_interval) {
 		err = -EINVAL;
 		goto out;
diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
index 86da14778658..6e29d92670c4 100644
--- a/mm/damon/reclaim.c
+++ b/mm/damon/reclaim.c
@@ -204,6 +204,9 @@ static int damon_reclaim_apply_parameters(void)
 	param_ctx->addr_unit = addr_unit;
 	param_ctx->min_region_sz = max(DAMON_MIN_REGION_SZ / addr_unit, 1);
 
+	if (!is_power_of_2(param_ctx->min_region_sz))
+		return -EINVAL;
+
 	if (!damon_reclaim_mon_attrs.aggr_interval) {
 		err = -EINVAL;
 		goto out;
-- 
2.53.0