When calculating the hotness of each region for the under-quota regions
prioritization, DAMON 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.
Reported-by: Jakub Acs <acsjakub@xxxxxxxxx>
Fixes: 198f0f4c58b9 ("mm/damon/vaddr,paddr: support pageout prioritization")
Cc: <stable@xxxxxxxxxxxxxxx> # 5.16.x
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
---
mm/damon/ops-common.c | 5 ++---
1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/mm/damon/ops-common.c b/mm/damon/ops-common.c
index ac1c3fa80f98..d25d99cb5f2b 100644
--- a/mm/damon/ops-common.c
+++ b/mm/damon/ops-common.c
@@ -73,7 +73,6 @@ void damon_pmdp_mkold(pmd_t *pmd, struct vm_area_struct *vma, unsigned long addr
int damon_hot_score(struct damon_ctx *c, struct damon_region *r,
struct damos *s)
{
- unsigned int max_nr_accesses;
int freq_subscore;
unsigned int age_in_sec;
int age_in_log, age_subscore;
@@ -81,8 +80,8 @@ int damon_hot_score(struct damon_ctx *c, struct damon_region *r,
unsigned int age_weight = s->quota.weight_age;
int hotness;
- max_nr_accesses = c->attrs.aggr_interval / c->attrs.sample_interval;
- freq_subscore = r->nr_accesses * DAMON_MAX_SUBSCORE / max_nr_accesses;
+ freq_subscore = r->nr_accesses * DAMON_MAX_SUBSCORE /
+ damon_max_nr_accesses(&c->attrs);
age_in_sec = (unsigned long)r->age * c->attrs.aggr_interval / 1000000;
for (age_in_log = 0; age_in_log < DAMON_MAX_AGE_IN_LOG && age_in_sec;
--
2.34.1
