The patch titled Subject: mm/damon/lru_sort: avoid divide-by-zero in hot threshold calculation has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-damon-lru_sort-avoid-divide-by-zero-in-hot-threshold-calculation.patch

This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...

This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------ From: SeongJae Park sj@kernel.org Subject: mm/damon/lru_sort: avoid divide-by-zero in hot threshold calculation Date: Thu, 19 Oct 2023 19:49:23 +0000

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: 40e983cca927 ("mm/damon: introduce DAMON-based LRU-lists Sorting") Signed-off-by: SeongJae Park sj@kernel.org Cc: stable@vger.kernel.org [6.0+] Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

mm/damon/lru_sort.c | 4 +--- 1 file changed, 1 insertion(+), 3 deletions(-)

--- a/mm/damon/lru_sort.c~mm-damon-lru_sort-avoid-divide-by-zero-in-hot-threshold-calculation +++ a/mm/damon/lru_sort.c @@ -193,9 +193,7 @@ static int damon_lru_sort_apply_paramete 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) _

Patches currently in -mm which might be from sj@kernel.org are

mm-damon-implement-a-function-for-max-nr_accesses-safe-calculation.patch mm-damon-core-avoid-divide-by-zero-during-monitoring-results-update.patch mm-damon-ops-common-avoid-divide-by-zero-during-region-hotness-calculation.patch mm-damon-lru_sort-avoid-divide-by-zero-in-hot-threshold-calculation.patch