mm/damon/lru_sort: avoid divide-by-zero in damon_lru_sort_apply_parameters()

commit 711f19dfd783ffb37ca4324388b9c4cb87e71363 upstream.

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>
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/mm/damon/lru_sort.c b/mm/damon/lru_sort.c
index 98a678129b06717073d3cbdf5a4521bc289e9254..61311800abc9847fba3ec4341e23e11a4f7fbf67 100644 (file)
--- a/mm/damon/lru_sort.c
+++ b/mm/damon/lru_sort.c
@@ -203,6 +203,9 @@ static int damon_lru_sort_apply_parameters(void)
        unsigned int hot_thres, cold_thres;
        int err = 0;
 
+       if (!damon_lru_sort_mon_attrs.sample_interval)
+               return -EINVAL;
+
        err = damon_set_attrs(ctx, &damon_lru_sort_mon_attrs);
        if (err)
                return err;