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authorSeongJae Park <sj@kernel.org>2023-10-19 19:49:24 +0000
committerAndrew Morton <akpm@linux-foundation.org>2023-10-25 16:47:15 -0700
commit62f76a7b53bfa2ecfe1570a5b1d0d574c576a56d (patch)
tree85df0492bcf83435b53bf99daf924ac4a1898550 /mm/damon
parent44063f125af4bb4efd1d500d8091fa33a98af325 (diff)
mm/damon/core: avoid divide-by-zero from pseudo-moving window length calculation
When calculating the pseudo-moving access rate, 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. Note that this is a fix for a commit that not in the mainline but mm tree. Link: https://lkml.kernel.org/r/20231019194924.100347-6-sj@kernel.org Fixes: ace30fb21af5 ("mm/damon/core: use pseudo-moving sum for nr_accesses_bp") Reported-by: Jakub Acs <acsjakub@amazon.de> Signed-off-by: SeongJae Park <sj@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/damon')
-rw-r--r--mm/damon/core.c2
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/damon/core.c b/mm/damon/core.c
index e194c8075235..aa2dc7087cd9 100644
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -1665,7 +1665,7 @@ void damon_update_region_access_rate(struct damon_region *r, bool accessed,
* aggr_interval, owing to validation of damon_set_attrs().
*/
if (attrs->sample_interval)
- len_window = attrs->aggr_interval / attrs->sample_interval;
+ len_window = damon_max_nr_accesses(attrs);
r->nr_accesses_bp = damon_moving_sum(r->nr_accesses_bp,
r->last_nr_accesses * 10000, len_window,
accessed ? 10000 : 0);