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.

Fixes: f04b0fedbe71 ("mm/damon/core: implement intervals auto-tuning") Signed-off-by: Honggyu Kim honggyu.kim@sk.com Cc: stable@vger.kernel.org --- mm/damon/core.c | 1 + 1 file changed, 1 insertion(+)

diff --git a/mm/damon/core.c b/mm/damon/core.c index b217e0120e09..2a6b8d1c2c9e 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -1449,6 +1449,7 @@ static unsigned long damon_get_intervals_score(struct damon_ctx *c) } } target_access_events = max_access_events * goal_bp / 10000; + target_access_events = target_access_events ? : 1; return access_events * 10000 / target_access_events; }