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[4/5] mm/damon/lru_sort: avoid divide-by-zero in hot threshold calculation

Message ID 20231019194924.100347-5-sj@kernel.org (mailing list archive)
State New
Headers show
Series avoid divide-by-zero due to max_nr_accesses overflow | expand

Commit Message

SeongJae Park Oct. 19, 2023, 7:49 p.m. UTC 
When calculating the hotness threshold for lru_prio scheme of
DAMON_LRU_SORT, the module divides some values by the maximum
nr_accesses.  However, due to the type of the related variables, simple
division-based calculation of the divisor can return zero.  As a result,
divide-by-zero is possible.  Fix it by using damon_max_nr_accesses(),
which handles the case.

Fixes: 40e983cca927 ("mm/damon: introduce DAMON-based LRU-lists Sorting")
Cc: <stable@vger.kernel.org> # 6.0.x
Signed-off-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/lru_sort.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)
diff mbox series

Patch

diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c
index 3ecdcc029443..f2e5f9431892 100644
--- a/mm/damon/lru_sort.c
+++ b/mm/damon/lru_sort.c
@@ -195,9 +195,7 @@  static int damon_lru_sort_apply_parameters(void)
 	if (err)
 		return err;
 
-	/* aggr_interval / sample_interval is the maximum nr_accesses */
-	hot_thres = damon_lru_sort_mon_attrs.aggr_interval /
-		damon_lru_sort_mon_attrs.sample_interval *
+	hot_thres = damon_max_nr_accesses(&damon_lru_sort_mon_attrs) *
 		hot_thres_access_freq / 1000;
 	scheme = damon_lru_sort_new_hot_scheme(hot_thres);
 	if (!scheme)