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=1792786093; b=rcLbVVJmLiZJSbOknQhMiLYJ0u25jlyp2LG5C3Pp6PEVUJVlwI6LmYA/hXzn6VUUBuA7 wwBgT1Y8wlDz4e9Nwgn98UDblXQ9IC2j9A2030FAZfhavnn8TfXWb2x3kYagzClRlqvVj fqhG5sXrIk+gYCPEPBgeOytFLid9qQzdW8Y/qZPEV4tt+v03ThXMhRhinorZz1p6FfQ8c /lk2YGFuX4lu2n5pI+0UF9No8zfQ7mfWL+lCgFenFIsSpoivba2dSqIv9qu2nuDgG1Bph ZSWbblDirG4Kj5u55l2/u65wEq0QF3WNbOUv3tce+Lk2qZ75gcEpZt/dH7BINkZ/9ag== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792786093; h=Received:DKIM-Signature:Date:From:To:Subject:Message-ID:In-Reply-To: References:MIME-Version:Content-Type:Content-Transfer-Encoding; bh=cgOLbH2Bki6NsD6SDMz7gOkkaaZ5+FtQ/PhC4n/dAYo=; b=ImKhrKKhp3f+I0lKRr05A3EMOxKrhewbKLak0y544ck8E+zKu8bIneK3ZeOnTu4SVvlN kfA/2CmJAYH959WqA8YHfOZ6MqBec0ZZp//RvDI6VOqEmzK9Ll/njgqU5tbAsRIDXhrrJ 4tIvmCaglDVG7KSPpy76zcarw2FY4U9zh+6pOrg2lI8P4YE/tMSBzr2dAHjgAvgqmUoyT CICKGhXFkMXXA2iaQGIpdQzfFQRyKVpRTeisCuCNHoSExigE1CV+vMTCx/FfJfnIUYGFr FK4lGxRK968YKZuUsRKUAMXQn2/RFMqH6Qtuqh7BBu1DbwH9PMEOTRGroSAAWEvWYgg== 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=BYGLg3bg; 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 893C6606A31D for ; Fri, 23 Oct 2026 20:08:13 +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=BYGLg3bg Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1CB721F01825; Fri, 23 Oct 2026 20:08:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1792786093; bh=cgOLbH2Bki6NsD6SDMz7gOkkaaZ5+FtQ/PhC4n/dAYo=; h=Date:From:To:Subject:In-Reply-To:References; b=BYGLg3bgeYsoQE6H05jMYgtW58c6Njh2yEDrpekYWtx5lo0RJWNjeDL82nxL75LxW hXW8IFGl6+qlondpYe8lULKe49AX6LxLgbCbb0+dP+Bur8LJEZSVfNMljUSeEWiO6i Oy2kp1VneoCsZk4drYWXX6wvYbspoBFll2l02Uc/SaXmlaMu2tUDh66KQ63fARskkR UqHeUElrhgyko9NPN8aktZT+UEIVkCZytUozptR029OyqsqcLJUwyt6SR3HUhqNFG+ WVCMo3Z+BnVXhCJw4GDhIW+vbCqkLAxXeeVL0NPgcPAi/6odc8mobwTBevUWu4U2+f HJ7rw3SfAaC9g== Date: Fri, 23 Oct 2026 13:08:12 -0700 From: Jakub Kicinski To: Matthias Tafelmeier , netdev@vger.kernel.org Subject: Re: [PATCH net] net: reject dev_weight products that overflow int Message-ID: <20261023130812.1ba2462a@kernel.org> In-Reply-To: <607851eb-e42b-46bc-928f-91db542fa9c0@gmx.net> References: <20261023114228.289161-1-jiayuan.chen@linux.dev> <20261023123102.3c30d01e@kernel.org> <607851eb-e42b-46bc-928f-91db542fa9c0@gmx.net> X-Mailing-List: netdev@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Fri, 23 Oct 2026 21:32:40 +0200 Matthias Tafelmeier wrote: > On 10/23/26 21:31, Jakub Kicinski wrote: > > On Fri, 23 Oct 2026 19:42:25 +0800 Jiayuan Chen wrote: > >> proc_do_dev_weight() sets the backlog NAPI weight and the qdisc quota > >> to dev_weight * dev_weight_rx_bias and dev_weight * dev_weight_tx_bias. > >> The three sysctls only have a lower bound of 1, so the products can > >> overflow int and end up <= 0, e.g. dev_weight=65536 and > >> dev_weight_rx_bias=65536 give a backlog weight of 0. > > Not sure anyone uses these, maybe we could cap them? > > 1k for dev weight 8 for bias? > > Capping does not make sense to me. Please don't email people off list. What are the values you know of being used in production?