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=1793553867; b=ER5Aq1V5nbu5qhaXGuqdij7p1PNGtxoz2MnITGuX2btdTjOPMwrp3kttIZvN37OlF4tm hFPpUangJCS24AOCyJoRMA0xKnAYtG8sXfASuV5uxYtl+BN4DauOnkT5N+18G0fySyJg3 F3BtP9qqEHlAppkAk7TJ581sThBQnewHEIVWtTDmoD0dFz867ZYNUTci7uukUxeAg202Y p4vAbMVWeFJ6xz/42xnHQ8nQxO3885nW66nCsvLyC8T+Lk61Edt7TwZp9Dt1L4XciQqS5 ksWx4tsoh2rKZwLWj1AQNlaidNjF/x9o6KPYCCWBvckIl6TmAGBBvPeK/myEceQ574Q== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793553867; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=147o5fUFXrCNV/qQ89AzwD3Q2RWXIphR1psPINCNBXo=; b=uafgkn01LQN9prJZkvS5+cKdL2pYNGDf3vhVHhmxI4ckIDsQHafvryJXi6BaSVm5gKyF cHv9aIWUCHGYlTSzSXy6gbJXox13BFU5mtfPDNamP8q6KVijfSzEcV32HGmsAtBet4dPz 33Ue/PTFEIG0hVJmi6mHGXMdA4osk7PlabTfal+KlzccHOGfcNouf57MUjQNSlNigS7mU Fd2LdQ1ALudS81hUhOHcdkuZnhRdyBS3zzVxAB0XS/fYxvu1Bxlel007/DcmAO976o3Ir 2Q7cs83HNtWtLcSPmWV/am7RKsGdTlwDI6VKIXtG+50M8i4xXVSO9ZqbrmYh1egwZ7w== 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=g5JOACo4; 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 53D9F606A324 for ; Sun, 1 Nov 2026 17:24:27 +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=g5JOACo4 Received: by smtp.kernel.org (Postfix) with ESMTPSA id BA5B11F000C1; Sun, 1 Nov 2026 17:24:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793553866; bh=147o5fUFXrCNV/qQ89AzwD3Q2RWXIphR1psPINCNBXo=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=g5JOACo4+6b+Jq5uh/Ar61G+OS9b9hg/cQjFW+mUjnTP0qJyhGAgbxu9o0r+UWbTD 8rHmk42uPdNPpN8aiv9ju6jTiKG3FpHhQvHNKlWcKoGs5Ht9uGX1KWD+TafwgR8RKD czAAC2dHgJMJqQsz4Gb9uZTPsUPL0Z8dcQoSXYmtXzgVKrynHPYu4qJzJC5XVZ1Nwr XXzAS0pZ+6fHwiKc/IeIwvM9UkGOMubOqWO6lqXoXTne7DG7YVNwoaY9BO4CWGx9yF raslDeLUIJv42JD30LN+HocU6kMlYEsekHDFWZJAcAj5sV+92hfS2yUgi0EEka/f01 LTTaL02QnB/Gg== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [RFC PATCH v2 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: <20261101171630.81477-5-sj@kernel.org> References: <20261101171630.81477-1-sj@kernel.org> <20261101171630.81477-5-sj@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Sun, 01 Nov 2026 17:24:25 +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/20261101171630.8147= 7-1-sj@kernel.org?part=3D4