mm/damon/core: avoid divide-by-zero from pseudo-moving window length …

…calculation 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. Link: https://lkml.kernel.org/r/[email protected] Fixes: ace30fb ("mm/damon/core: use pseudo-moving sum for nr_accesses_bp") Reported-by: Jakub Acs <[email protected]> Signed-off-by: SeongJae Park <[email protected]> Signed-off-by: Andrew Morton <[email protected]>
niw · Oct 25, 2023 · 62f76a7 · 62f76a7
1 parent 44063f1
commit 62f76a7
Showing 1 changed file with 1 addition and 1 deletion.
diff --git 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);