[PATCH 6.1.y] mm/damon/reclaim: avoid divide-by-zero in damon_reclaim_apply_parameters()

[PATCH 6.1.y] mm/damon/reclaim: avoid divide-by-zero in damon_reclaim_apply_parameters()

[SeongJae Park]

From: Quanmin Yan <yanquanmin1@huawei.com>

When creating a new scheme of DAMON_RECLAIM, the calculation of
'min_age_region' uses 'aggr_interval' as the divisor, which may lead to
division-by-zero errors.  Fix it by directly returning -EINVAL when such a
case occurs.

Link: https://lkml.kernel.org/r/20250827115858.1186261-3-yanquanmin1@huawei.com
Fixes: f5a79d7c0c87 ("mm/damon: introduce struct damos_access_pattern")
Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: ze zuo <zuoze1@huawei.com>
Cc: <stable@vger.kernel.org>	[6.1+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
(cherry picked from commit e6b543ca9806d7bced863f43020e016ee996c057)
Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/reclaim.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/damon/reclaim.c b/mm/damon/reclaim.c
index cc337e94acfd..7952a0b7f409 100644
--- a/mm/damon/reclaim.c
+++ b/mm/damon/reclaim.c
@@ -157,6 +157,9 @@ static int damon_reclaim_apply_parameters(void)
 	struct damos *scheme, *old_scheme;
 	int err = 0;
 
+	if (!damon_reclaim_mon_attrs.aggr_interval)
+		return -EINVAL;
+
 	err = damon_set_attrs(ctx, &damon_reclaim_mon_attrs);
 	if (err)
 		return err;
-- 
2.39.5