Commit 44063f12 authored by SeongJae Park's avatar SeongJae Park Committed by Andrew Morton
Browse files

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

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: 40e983cc ("mm/damon: introduce DAMON-based LRU-lists Sorting")
Signed-off-by: default avatarSeongJae Park <sj@kernel.org>
Reported-by: default avatarJakub Acs <acsjakub@amazon.de>
Cc: <stable@vger.kernel.org>	[6.0+]
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 3bafc47d

mm/damon/lru_sort.c

+1 −3
Original line number Diff line number Diff line
@@ -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)