When calculating the pseudo-moving access rate, DAMON 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.
Note that this is a fix for a commit that not in the mainline but mm
tree.
Fixes: ace30fb21af5 ("mm/damon/core: use pseudo-moving sum for nr_accesses_bp")
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
---
Note that this is for a patch in mm-stable that not yet merged into the
mainline.
mm/damon/core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/damon/core.c b/mm/damon/core.c
index e194c8075235..aa2dc7087cd9 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -1665,7 +1665,7 @@ void damon_update_region_access_rate(struct damon_region *r, bool accessed,
* aggr_interval, owing to validation of damon_set_attrs().
*/
if (attrs->sample_interval)
- len_window = attrs->aggr_interval / attrs->sample_interval;
+ len_window = damon_max_nr_accesses(attrs);
r->nr_accesses_bp = damon_moving_sum(r->nr_accesses_bp,
r->last_nr_accesses * 10000, len_window,
accessed ? 10000 : 0);
--
2.34.1
