From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 90B5842252D; Tue, 7 Jul 2026 13:50:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783432255; cv=none; b=sF2jROngmnHoaVq1j0+mvtu5rNw/ny0vS5OQ+yE3GrXT8WV6YRhk+EIeClFdAYv4lcP/ozP700fEGR5lWgbcFr+yi1cL6HtCm88zm9fKCVVkd/BUZHtIF4GCImyZtAYc0/A/B1/qHWY5/Za75JFAfiSqdNxk1unOSZuTkuc9+h8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1783432255; c=relaxed/simple; bh=/CKErzgrvjCi5gJb1b6KPLWiCgkDsNxqIuMCwPTw83M=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=aRGfVOxXADNAIOZisIRh+nZ/0zWt4FRfvwYkcXn0r/s2dokzTQDheQIHJuqwEf0alQSD0eysipmoefz2Hz8yH0/lAWyhTV/blRGx7BCb0E4wX4VIMO/pllbORePDFdJv5tOKRIH89yEvi1WeASvddHsMbgVm5o04bo7ifHddBnw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=gSIC6W3f; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="gSIC6W3f" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8A0D31F000E9; Tue, 7 Jul 2026 13:50:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783432250; bh=GY3vV+uG8yWd6R6f7yGxLhbvEHq+g5ke+H2XqmQ5/Pc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; 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> Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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