During the calculation of 'hot_thres' and 'cold_thres', either
'sample_interval' or 'aggr_interval' is used as the divisor,
which may lead to division-by-zero errors. Fix it by directly
returning -EINVAL when such a case occurs. Additionally, since
'aggr_interval' is already required to be set no smaller than
'sample_interval' in damon_set_attrs(), only the case where
'sample_interval' is zero needs to be checked.

Fixes: 40e983cca927 ("mm/damon: introduce DAMON-based LRU-lists Sorting")
Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>
---
 mm/damon/lru_sort.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c
index 151a9de5ad8b..b5a5ed16a7a5 100644
--- a/mm/damon/lru_sort.c
+++ b/mm/damon/lru_sort.c
@@ -198,6 +198,11 @@ static int damon_lru_sort_apply_parameters(void)
 	if (err)
 		return err;
 
+	if (!damon_lru_sort_mon_attrs.sample_interval) {
+		err = -EINVAL;
+		goto out;
+	}
+
 	err = damon_set_attrs(ctx, &damon_lru_sort_mon_attrs);
 	if (err)
 		goto out;
-- 
2.43.0

On Tue, 26 Aug 2025 11:36:52 +0800 Quanmin Yan <yanquanmin1@huawei.com> wrote:

> During the calculation of 'hot_thres' and 'cold_thres', either
> 'sample_interval' or 'aggr_interval' is used as the divisor,
> which may lead to division-by-zero errors. Fix it by directly
> returning -EINVAL when such a case occurs. Additionally, since
> 'aggr_interval' is already required to be set no smaller than
> 'sample_interval' in damon_set_attrs(), only the case where
> 'sample_interval' is zero needs to be checked.

Nice catch and fix!

> 
> Fixes: 40e983cca927 ("mm/damon: introduce DAMON-based LRU-lists Sorting")

Let's add Cc: stable@

> Signed-off-by: Quanmin Yan <yanquanmin1@huawei.com>

Reviewed-by: SeongJae Park <sj@kernel.org>


Thanks,
SJ

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