+ mm-damon-reclaim-avoid-divide-by-zero-in-damon_reclaim_apply_parameters.patch added to mm-hotfixes-unstable branch

+ mm-damon-reclaim-avoid-divide-by-zero-in-damon_reclaim_apply_parameters.patch added to mm-hotfixes-unstable branch

[Andrew Morton]

The patch titled
     Subject: mm/damon/reclaim: avoid divide-by-zero in damon_reclaim_apply_parameters()
has been added to the -mm mm-hotfixes-unstable branch.  Its filename is
     mm-damon-reclaim-avoid-divide-by-zero-in-damon_reclaim_apply_parameters.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-damon-reclaim-avoid-divide-by-zero-in-damon_reclaim_apply_parameters.patch

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

Before you just go and hit "reply", please:
   a) Consider who else should be cc'ed
   b) Prefer to cc a suitable mailing list as well
   c) Ideally: find the original patch on the mailing list and do a
      reply-to-all to that, adding suitable additional cc's

*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days

------------------------------------------------------
From: Quanmin Yan <yanquanmin1@huawei.com>
Subject: mm/damon/reclaim: avoid divide-by-zero in damon_reclaim_apply_parameters()
Date: Wed, 27 Aug 2025 19:58:58 +0800

When creating a new scheme of DAMON_RECLAIM, the calculation of
'min_age_region' uses 'aggr_interval' as the divisor, which may lead to
division-by-zero errors.  Fix it by directly returning -EINVAL when such a
case occurs.

Link: https://lkml.kernel.org/r/20250827115858.1186261-3-yanquanmin1@huawei.com
Fixes: f5a79d7c0c87 ("mm/damon: introduce struct damos_access_pattern")
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>	[6.1+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/damon/reclaim.c |    5 +++++
 1 file changed, 5 insertions(+)

--- a/mm/damon/reclaim.c~mm-damon-reclaim-avoid-divide-by-zero-in-damon_reclaim_apply_parameters
+++ a/mm/damon/reclaim.c
@@ -194,6 +194,11 @@ static int damon_reclaim_apply_parameter
 	if (err)
 		return err;
 
+	if (!damon_reclaim_mon_attrs.aggr_interval) {
+		err = -EINVAL;
+		goto out;
+	}
+
 	err = damon_set_attrs(param_ctx, &damon_reclaim_mon_attrs);
 	if (err)
 		goto out;
_

Patches currently in -mm which might be from yanquanmin1@huawei.com are

mm-damon-core-prevent-unnecessary-overflow-in-damos_set_effective_quota.patch
mm-damon-lru_sort-avoid-divide-by-zero-in-damon_lru_sort_apply_parameters.patch
mm-damon-reclaim-avoid-divide-by-zero-in-damon_reclaim_apply_parameters.patch