From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793478738; b=s5XEVp9XZDsapJ+fK1JdMAam5bP93un2xYSNmxubF39Q1sMajW6dM667+3zStw7eoBA5 2X5+LAHuWRZc27U4dDSF9BqH5gpp0Qg3OrU1ZcYDnu3oxw3ZlNXItTlaVmUjjWRk3iD4+ eSN011ftXOEaaFREyNhBtAIp0yQD+57ox6Y3AxQomsgEh5QVryuyYdpnlO3FTalvztCb4 8VrqnpaFEA2yefO3YUdvh9cY7CcZeK3UrvMpFrFnUxOma1z+7+WG3EOYE1ljkqSW7Yy2I qzBVZHtDD9OseRmsQbPJkQVWvsPyB2xANSGLWlwgM+oyvvUj5aQEDnJGPkIFOj343Qg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793478738; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=FMgfvRp5JPcIJgWwSWUQxOJ1IubweUnndfqAWm80QtI=; b=lirWvs9RHE8W8Oi5YgCP/zNpwhmCnbAhzKYt/U7vbpLAPNrXiYi7/LDfaGDTXLRd4aiR S2ToBXB+iiPacYeqO0Hr2u659qHuXZSjYYqGoUhB9P8k0kojjxBmH0pN5a+GR+s58+5IX 6sVx6EWxkbjVc0/fZY5LuPRsa5ipA4LekVl25JbMftj5lcoAIbcanPGNlpbO1tic+adtr tVlA+GqrxPZRKdh4YYAXhBLdb9P6VQ2irEsRxrVA8bbM3Ne2AQFjzdbYDL44a6jZyGcDt +YylgNs0A4leEtDP104K8A1T8vw1SLXXlO2giBTzsMjV54S+agXYB8L2Y1r4j83ANAQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=bBxsUNea; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 3B99F606A31A for ; Sat, 31 Oct 2026 20:32:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=bBxsUNea Received: by smtp.kernel.org (Postfix) with ESMTPSA id EA6091F000C1; Sat, 31 Oct 2026 20:32:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793478738; bh=FMgfvRp5JPcIJgWwSWUQxOJ1IubweUnndfqAWm80QtI=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=bBxsUNeak4L10FMk1GCwNSStkMoFzMMtIbTeBSg8QzihLqkryIdhlsJoV9ompFNNF JySi+4MtCD9eNXqLlE0eNeeFrTc1i7zbwjmiEyqNuvfEHiaqEmRf4VrsFWJelJMLry bQxErMQ+FFZCAsRBBrnmLUGyb5rPKcaFxudURr82esHUJE+KVVJzE4oeSPBjDYy5Mv k65J3K0KnRR41q6XfA6km+hfbBeSwk+qgdbGrYp8Fetkkgjgia+lst8AUq3VbtKbFC XQRGWQfxkyzoC23I0ByWo++YT9J7qAMqM+S3HgnRkJeIUAl2NLx56M3NPdrc+3VSLD JeWgi5mD/gRxQ== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [RFC PATCH 4/6] mm/damon/sysfs-schemes: drop redundant and racy zero target_value check Reply-To: sashiko-reviews@lists.linux.dev To: "SJ Park" Cc: damon@lists.linux.dev In-Reply-To: <20261031202614.96036-5-sj@kernel.org> References: <20261031202614.96036-1-sj@kernel.org> <20261031202614.96036-5-sj@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Sat, 31 Oct 2026 20:32:17 +0000 X-Mailing-List: damon@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > DAMON sysfs interface disallowed zero target_value because it could > result in divide-by-zero in damos_quota_store(). Because similar checks > were duplicated to other DAMON API callers, a patch series that starts > with commit 610c4438fb66 ("mm/damon/core: error > damos_commit_quota_goal() for zero target_value") added a same check in > the core layer central parameters, and dropped redundant checks in > DAMON_LRU_SORT and DAMON_SAMPLIE_MTIER. It forgot to drop that in the > DAMON sysfs interface. >=20 > Now the zero target_value check in DAMON sysfs interface is only > redundant. Further, it has a time-of-check to time-of-use (toctou) race > with target_value_store(). It can confuse readers to believe [1] the > division-by-zero can still happen. Drop the redundant and racy check. >=20 > [1] https://lore.kernel.org/20261021005234.94107-1-sj@kernel.org >=20 > Signed-off-by: SJ Park Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261031202614.9603= 6-1-sj@kernel.org?part=3D4