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authorSeongJae Park <sj@kernel.org>2023-10-19 22:49:22 +0300
committerAndrew Morton <akpm@linux-foundation.org>2023-10-26 02:47:15 +0300
commit3bafc47d3c4a2fc4d3b382aeb3c087f8fc84d9fd (patch)
treeca24b9c75176b8588462d1ceb65dbb290d058e3a /mm/damon
parentd35963bfb05877455228ecec6b194f624489f96a (diff)
downloadlinux-3bafc47d3c4a2fc4d3b382aeb3c087f8fc84d9fd.tar.xz
mm/damon/ops-common: avoid divide-by-zero during region hotness calculation
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. Link: https://lkml.kernel.org/r/20231019194924.100347-4-sj@kernel.org Fixes: 198f0f4c58b9 ("mm/damon/vaddr,paddr: support pageout prioritization") Signed-off-by: SeongJae Park <sj@kernel.org> Reported-by: Jakub Acs <acsjakub@amazon.de> Cc: <stable@vger.kernel.org> [5.16+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/damon')
-rw-r--r--mm/damon/ops-common.c5
1 files 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;