From: SeongJae Park Date: Thu, 19 Oct 2023 19:49:22 +0000 (+0000) Subject: mm/damon/ops-common: avoid divide-by-zero during region hotness calculation X-Git-Tag: v6.1.68~569 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=834a800c58ea494483d63aa077debfef3ac7199f;p=platform%2Fkernel%2Flinux-starfive.git mm/damon/ops-common: avoid divide-by-zero during region hotness calculation commit 3bafc47d3c4a2fc4d3b382aeb3c087f8fc84d9fd upstream. 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 Reported-by: Jakub Acs Cc: [5.16+] Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- diff --git a/mm/damon/ops-common.c b/mm/damon/ops-common.c index 13b9997..0b75a8d 100644 --- a/mm/damon/ops-common.c +++ b/mm/damon/ops-common.c @@ -87,7 +87,6 @@ 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; @@ -95,8 +94,8 @@ 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;