This is a note to let you know that I've just added the patch titled
mm/damon/core: avoid divide-by-zero during monitoring results update
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-damon-core-avoid-divide-by-zero-during-monitoring-results-update.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d35963bfb05877455228ecec6b194f624489f96a Mon Sep 17 00:00:00 2001
From: SeongJae Park <sj@xxxxxxxxxx>
Date: Thu, 19 Oct 2023 19:49:21 +0000
Subject: mm/damon/core: avoid divide-by-zero during monitoring results update
From: SeongJae Park <sj@xxxxxxxxxx>
commit d35963bfb05877455228ecec6b194f624489f96a upstream.
When monitoring attributes are changed, DAMON updates access rate of the
monitoring results accordingly. For that, it 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/20231019194924.100347-3-sj@xxxxxxxxxx
Fixes: 2f5bef5a590b ("mm/damon/core: update monitoring results for new monitoring attributes")
Signed-off-by: SeongJae Park <sj@xxxxxxxxxx>
Reported-by: Jakub Acs <acsjakub@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> [6.3+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/damon/core.c | 10 ++--------
1 file changed, 2 insertions(+), 8 deletions(-)
--- a/mm/damon/core.c
+++ b/mm/damon/core.c
@@ -476,20 +476,14 @@ static unsigned int damon_age_for_new_at
static unsigned int damon_accesses_bp_to_nr_accesses(
unsigned int accesses_bp, struct damon_attrs *attrs)
{
- unsigned int max_nr_accesses =
- attrs->aggr_interval / attrs->sample_interval;
-
- return accesses_bp * max_nr_accesses / 10000;
+ return accesses_bp * damon_max_nr_accesses(attrs) / 10000;
}
/* convert nr_accesses to access ratio in bp (per 10,000) */
static unsigned int damon_nr_accesses_to_accesses_bp(
unsigned int nr_accesses, struct damon_attrs *attrs)
{
- unsigned int max_nr_accesses =
- attrs->aggr_interval / attrs->sample_interval;
-
- return nr_accesses * 10000 / max_nr_accesses;
+ return nr_accesses * 10000 / damon_max_nr_accesses(attrs);
}
static unsigned int damon_nr_accesses_for_new_attrs(unsigned int nr_accesses,
Patches currently in stable-queue which might be from sj@xxxxxxxxxx are
queue-6.6/mm-damon-implement-a-function-for-max-nr_accesses-safe-calculation.patch
queue-6.6/mm-damon-ops-common-avoid-divide-by-zero-during-region-hotness-calculation.patch
queue-6.6/mm-damon-sysfs-check-error-from-damon_sysfs_update_target.patch
queue-6.6/mm-damon-lru_sort-avoid-divide-by-zero-in-hot-threshold-calculation.patch
queue-6.6/mm-damon-core-avoid-divide-by-zero-during-monitoring-results-update.patch
queue-6.6/mm-damon-sysfs-schemes-handle-tried-region-directory-allocation-failure.patch
queue-6.6/mm-damon-sysfs-update-monitoring-target-regions-for-online-input-commit.patch
queue-6.6/mm-damon-sysfs-schemes-handle-tried-regions-sysfs-directory-allocation-failure.patch
queue-6.6/mm-damon-sysfs-remove-requested-targets-when-online-commit-inputs.patch
queue-6.6/mm-damon-core.c-avoid-unintentional-filtering-out-of-schemes.patch
