The patch titled Subject: mm/damon: fix divide by zero in damon_get_intervals_score() has been added to the -mm mm-hotfixes-unstable branch. Its filename is mm-damon-fix-divide-by-zero-in-damon_get_intervals_score.patch
This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches...
This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------ 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; }
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Patches currently in -mm which might be from honggyu.kim@sk.com are
samples-damon-fix-damon-sample-prcl-for-start-failure.patch samples-damon-fix-damon-sample-wsse-for-start-failure.patch samples-damon-fix-damon-sample-mtier-for-start-failure.patch mm-damon-fix-divide-by-zero-in-damon_get_intervals_score.patch