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=1792947232; b=QHOpyIQLqkLpzOyu7ETmLVOd3uv67QeAf5lgLuKEX+C5TiYA6O82k4nESyUUeCpXu242 CkUg3x4ZT3l+zQTQwsSwkQMjsoYXO1+5ip6YDH6Zx7UJtTaB59zog57HMlB6ZBZXdNmrX ekTJUbgda3sNNNDKu52kXE8ma0PF9dBJNEAuK7a3opPHgZip/KyTq4necWbvKDnSxAj9K HpE9GmeAN6tk+X9ZJ5JEDMcTLuNJwv8hTUp+inctR4DpDAzsrTT3sgBu4RtLzQQ6IENgC phQ/C4MHQu3iVlFCbxEiF3Cdju0v4atD4OiqBtFbcjHJrMFvMj+mr/6xk6nU0KgCKYA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792947232; h=Received:DKIM-Signature:Message-ID:From:Subject:Reply-To:To:Cc: In-Reply-To:References:Content-Type:Content-Transfer-Encoding:Date; bh=4aXGV9omOA5pjV7TB6r8XBSmZPCz3U3HoTBjml181DM=; b=Y1cntz8APPhxRpiM0bwJ6uyTqdqzUPEwOgHd7vve0yXPXO2bviQFMErInVhMjSPPV030 ILXG8QO/8lGTXsflKnTjNeYjQa350tgcB1Sm/vWEuwP2zTxlsk/jdYytukCOcRHcJH1ux FOLdVqnNEbx5lxbwohS8PByGXr0NUCpClgSdlN5WwdGJuC2/KQ4ZkcEVLUHwbCiCeAWMu CUdUixF0jBytCnFEdj/n+InhKobj36dcihQLoOvM/V5cFuMklvPhjzVKqJQ5MWOgLK3Rf kRcKc2wPS/h6b8QCDfZmMvGJ73FCRd+RSeCGmU7VdkSUQMmDGyqRDd6zTlb6bHyIvCQ== 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=jc6wvD8j; 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 31754606A31A for ; Sun, 25 Oct 2026 16:53:51 +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=jc6wvD8j Received: by smtp.kernel.org (Postfix) with ESMTPSA id A475F1F01825; Sun, 25 Oct 2026 16:53:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792947231; bh=4aXGV9omOA5pjV7TB6r8XBSmZPCz3U3HoTBjml181DM=; h=From:Subject:Reply-To:To:Cc:In-Reply-To:References:Date; b=jc6wvD8jMx3JN2NRcPgx5z5Qe9DVWcG/hoc1nzXOj2z3DZV5V2/irY34FDwJxgjYi JdQSreELmBpW0/OEkdZdAyPdiIRnNMqWad6EYRhVn2xEihnCoJO60pb4tWjSiqvlH2 le1PD+MUhiep7OrhF6OsFS1ehiHHVfkhkHou+7gkRbBtk7iLwyGhR5JBAnv9txiWlb gnR6NoiefyehZzaE9T/seoCiJGZcSKgIwBknl/9+v8qyQX0PwwQgTU8eHNeRsxO6QT 5S/Y3VC6awQohxEr5UImF0bIB3kFbtuS7IZr/Fv5aCJeHa7uYx6qJNmVkskLDTUBkT GrKA+LVSL/2/g== Message-ID: From: sashiko-bot@kernel.org Subject: Re: [PATCH 2/3] mm/damon/core: move static variable last_nr_regions to damon_ctx Reply-To: sashiko-reviews@lists.linux.dev To: "SJ Park" Cc: damon@lists.linux.dev In-Reply-To: <20261025164808.152048-3-sj@kernel.org> References: <20261025164808.152048-1-sj@kernel.org> <20261025164808.152048-3-sj@kernel.org> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Sun, 25 Oct 2026 16:53:51 +0000 X-Mailing-List: damon@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list > kdamond_split_regions() uses a static variable last_nr_regions, to infer > if the region boundaries are too stable. If it looks too stable, it > does a more aggressive region split because it might be a fake stability > coming from non-aggressive split. Because the variable is static, the > inference can be racy and wrong when multiple kdamonds are running in > parallel. >=20 > The user impact is not critical. No crash, no leak. DAMON's > best-effort monitoring accuracy can be degraded when multiple kdamonds > are used in parallel and the workload has certain access patterns. Still > it is a bug that is better to fix. >=20 > Move the variable into the damon_ctx struct to fix the problem. >=20 > Fixes: 75c1c2b53c78 ("mm/damon/dbgfs: support multiple contexts") > Cc: # 5.15.x > Closes: https://sashiko.dev/#/bug/linux-eebfcdde-2881-48ef-8df1-e2019d2a4= 7f2 > Signed-off-by: SJ Park Sashiko has reviewed this patch and found no issues. --=20 Sashiko AI review =C2=B7 https://sashiko.dev/#/patchset/20261025164808.1520= 48-1-sj@kernel.org?part=3D2