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b=gSIC6W3fIjsjD6tAbqohQR+5KgzASN3vZf47SOlZUIvyza1ATwUpS/t78YYf9VHl4 uyJSfKU5XTs2uE3toGAYAy7OQ+eGA9zIe+mGH4xUXTFweDh7jrxBst/unj08ZGclzT EKh7kOeUoCzX89UXMZHTcqeXZXNSGVNpbAAEdsCXBKFqqHEH1e2w7Pvawv0JI01kJ0 hCKiDILlT4G2yesyvCe2gCYLnBwsY4nMTTyviZITOiQD+4gtHMEXY7WiX9Ac/n0rZB Q/pZE2DQwfzgYdUkHsRHK+8Au3ZmiRf0pYks5wyh1gwEY5m0l02Dl9jviS+mX3LLGh 1mIqvWCgkJZ3w== From: SJ Park To: Cc: SJ Park , Andrew Morton , damon@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH v1.1 1/7] mm/damon/core: remove obsolete comment for nr_to_bp() divide-by-zero Date: Tue, 7 Jul 2026 06:50:30 -0700 Message-ID: <20260707135038.90068-2-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20260707135038.90068-1-sj@kernel.org> References: <20260707135038.90068-1-sj@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: tydhq6h51wjt76mrbnrrojbnz4h9ckfe X-Rspamd-Queue-Id: 89FEA40007 X-Rspamd-Server: rspam01 X-Rspam-User: X-HE-Tag: 1783432251-713328 X-HE-Meta: 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 KAh3Qsqv h8PfO218cTEXHmhAvPBAXEfmm6BtwxRj760dZAcE7yHl/qFexwt+gcvjeSvp0h7NZaZIrMex25EbEoPyU9QmHTz1KwLpjtEBLJbkvSssZRYV55LhwKaGpzUnHUJpmUGqJhL2IPvRngxk+xEuM6Gn0ZBae5vD3IVeeE8r+nmqzH/3iZz86CU+dnvlztnslyQXhmc53e27a1Ukcvdj2RCw4lF6lokwDSCD93hJUgOP+m15+GHnVRixwOvSe0eLVwgXnBRTYFXECbyf05Diebyx4l0Jl+g== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: damon_nr_accesses_to_accesses_bp() warns it can trigger division-by-zero when the aggregation interval is zero. Commit 35d4a3cf70a8 ("mm/damon/ops-common: handle extreme intervals in damon_hot_score()") modified damon_nr_samples_per_aggr() to always return non-zero. Hence no division-by-zero of the note can happen. Remove the obsolete comment on the function and its test code. Also remove the unnecessary guard code in the test. Signed-off-by: SJ Park --- mm/damon/core.c | 8 +------- mm/damon/tests/core-kunit.h | 12 ------------ 2 files changed, 1 insertion(+), 19 deletions(-) diff --git a/mm/damon/core.c b/mm/damon/core.c index 390e00b3685ef..a15005db82899 100644 --- a/mm/damon/core.c +++ b/mm/damon/core.c @@ -883,13 +883,7 @@ static unsigned int damon_accesses_bp_to_nr_accesses( return accesses_bp * damon_max_nr_accesses(attrs) / 10000; } -/* - * Convert nr_accesses to access ratio in bp (per 10,000). - * - * Callers should ensure attrs.aggr_interval is not zero, like - * damon_update_monitoring_results() does . Otherwise, divide-by-zero would - * happen. - */ +/* 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) { diff --git a/mm/damon/tests/core-kunit.h b/mm/damon/tests/core-kunit.h index 0124f83b39b83..224a3ecaa0701 100644 --- a/mm/damon/tests/core-kunit.h +++ b/mm/damon/tests/core-kunit.h @@ -582,18 +582,6 @@ static void damon_test_nr_accesses_to_accesses_bp(struct kunit *test) .aggr_interval = ((unsigned long)UINT_MAX + 1) * 10 }; - /* - * In some cases such as 32bit architectures where UINT_MAX is - * ULONG_MAX, attrs.aggr_interval becomes zero. Calling - * damon_nr_accesses_to_accesses_bp() in the case will cause - * divide-by-zero. Such case is prohibited in normal execution since - * the caution is documented on the comment for the function, and - * damon_update_monitoring_results() does the check. Skip the test in - * the case. - */ - if (!attrs.aggr_interval) - kunit_skip(test, "aggr_interval is zero."); - KUNIT_EXPECT_EQ(test, damon_nr_accesses_to_accesses_bp(123, &attrs), 0); } -- 2.47.3