mm/damon/lru_sort: avoid divide-by-zero in hot threshold calculation

commit 44063f1 upstream.

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.

Link: https://lkml.kernel.org/r/20231019194924.100347-5-sj@kernel.org
Fixes: 40e983c ("mm/damon: introduce DAMON-based LRU-lists Sorting")
Signed-off-by: SeongJae Park <sj@kernel.org>
Reported-by: Jakub Acs <acsjakub@amazon.de>
Cc: <stable@vger.kernel.org>	[6.0+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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)