FAILED: patch "[PATCH] mm/damon/lru_sort: avoid divide-by-zero in" failed to apply to 6.6-stable tree

[<gregkh@linuxfoundation.org>]

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;