The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x 711f19dfd783ffb37ca4324388b9c4cb87e71363 # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025091317-snowsuit-earthen-6ad7@gregkh' --subject-prefix 'PATCH 6.6.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 711f19dfd783ffb37ca4324388b9c4cb87e71363 Mon Sep 17 00:00:00 2001 From: Quanmin Yan yanquanmin1@huawei.com Date: Wed, 27 Aug 2025 19:58:57 +0800 Subject: [PATCH] mm/damon/lru_sort: avoid divide-by-zero in damon_lru_sort_apply_parameters()

Patch series "mm/damon: avoid divide-by-zero in DAMON module's parameters application".

DAMON's RECLAIM and LRU_SORT modules perform no validation on user-configured parameters during application, which may lead to division-by-zero errors.

Avoid the divide-by-zero by adding validation checks when DAMON modules attempt to apply the parameters.

This patch (of 2):

During the calculation of 'hot_thres' and 'cold_thres', either 'sample_interval' or 'aggr_interval' is used as the divisor, which may lead to division-by-zero errors. Fix it by directly returning -EINVAL when such a case occurs. Additionally, since 'aggr_interval' is already required to be set no smaller than 'sample_interval' in damon_set_attrs(), only the case where 'sample_interval' is zero needs to be checked.

Link: https://lkml.kernel.org/r/20250827115858.1186261-2-yanquanmin1@huawei.com Fixes: 40e983cca927 ("mm/damon: introduce DAMON-based LRU-lists Sorting") Signed-off-by: Quanmin Yan yanquanmin1@huawei.com Reviewed-by: SeongJae Park sj@kernel.org Cc: Kefeng Wang wangkefeng.wang@huawei.com Cc: ze zuo zuoze1@huawei.com Cc: stable@vger.kernel.org [6.0+] Signed-off-by: Andrew Morton akpm@linux-foundation.org

diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c index 151a9de5ad8b..b5a5ed16a7a5 100644 --- a/mm/damon/lru_sort.c +++ b/mm/damon/lru_sort.c @@ -198,6 +198,11 @@ static int damon_lru_sort_apply_parameters(void) if (err) return err;

+ if (!damon_lru_sort_mon_attrs.sample_interval) { + err = -EINVAL; + goto out; + } + err = damon_set_attrs(ctx, &damon_lru_sort_mon_attrs); if (err) goto out;