From: Andrew Morton <akpm@linux-foundation.org>
To: mm-commits@vger.kernel.org,stable@vger.kernel.org,sj@kernel.org,honggyu.kim@sk.com,akpm@linux-foundation.org
Subject: [merged mm-hotfixes-stable] mm-damon-fix-divide-by-zero-in-damon_get_intervals_score.patch removed from -mm tree
Date: Wed, 09 Jul 2025 21:09:22 -0700 [thread overview]
Message-ID: <20250710040922.C069DC4CEE3@smtp.kernel.org> (raw)
The quilt patch titled
Subject: mm/damon: fix divide by zero in damon_get_intervals_score()
has been removed from the -mm tree. Its filename was
mm-damon-fix-divide-by-zero-in-damon_get_intervals_score.patch
This patch was dropped because it was merged into the mm-hotfixes-stable branch
of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
------------------------------------------------------
From: Honggyu Kim <honggyu.kim@sk.com>
Subject: mm/damon: fix divide by zero in damon_get_intervals_score()
Date: Wed, 2 Jul 2025 09:02:04 +0900
The current implementation allows having zero size regions with no special
reasons, but damon_get_intervals_score() gets crashed by divide by zero
when the region size is zero.
[ 29.403950] Oops: divide error: 0000 [#1] SMP NOPTI
This patch fixes the bug, but does not disallow zero size regions to keep
the backward compatibility since disallowing zero size regions might be a
breaking change for some users.
In addition, the same crash can happen when intervals_goal.access_bp is
zero so this should be fixed in stable trees as well.
Link: https://lkml.kernel.org/r/20250702000205.1921-5-honggyu.kim@sk.com
Fixes: f04b0fedbe71 ("mm/damon/core: implement intervals auto-tuning")
Signed-off-by: Honggyu Kim <honggyu.kim@sk.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
mm/damon/core.c | 1 +
1 file changed, 1 insertion(+)
--- a/mm/damon/core.c~mm-damon-fix-divide-by-zero-in-damon_get_intervals_score
+++ a/mm/damon/core.c
@@ -1449,6 +1449,7 @@ static unsigned long damon_get_intervals
}
}
target_access_events = max_access_events * goal_bp / 10000;
+ target_access_events = target_access_events ? : 1;
return access_events * 10000 / target_access_events;
}
_
Patches currently in -mm which might be from honggyu.kim@sk.com are
samples-damon-change-enable-parameters-to-enabled.patch
reply other threads:[~2025-07-10 4:09 UTC|newest]
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