From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 2E58ADDC1 for ; Thu, 2 Jan 2025 22:36:48 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735857409; cv=none; b=KBMex0GLJnX8PxsmwqYlP0bP4D9k91wAtiNYT+iWD3HwhdB4EkHq4WfTu3XW+f9W0xBmixFrz8w+Pc/KNFxbPlS8lJqBCSfM5fuZr258HZUND5lRmswAF+arh8gJIzBd2ZRwuHODzeGlgEQIsKpanffxNmh/pph2AT40aYDsq5Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735857409; c=relaxed/simple; bh=ocaRHi59zpGnTRXE9GIhf/VGujjxdQjnIcymJYvU5LI=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=pmzifuSQMTlittogud75D34G42mQjcIFtmzsFCuvPR/JAMgbzkUdMadbYZJeiFimQ8R/V2BD8n6hJZYyyNBgaGiU03Vw9wU1n1YP01LDB+JUTnmMyNaAiVdaLRemJmJGXS/Wux+G+TRShPtDUnyDFVzAWNwpqPawMVGovqcqPCc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=JwSwLAJ1; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="JwSwLAJ1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 77123C4CED0; Thu, 2 Jan 2025 22:36:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1735857408; bh=ocaRHi59zpGnTRXE9GIhf/VGujjxdQjnIcymJYvU5LI=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=JwSwLAJ1xPIRdbyoIwlj+HPFrfy2yEEcbz6w5Do4mLo2v3DVdwO0PEU36LE2VshoN EyIgZoEqL6AhVCGRijVxbi3Prx8c0Fjfsb89/jhygm7JhT9zGCt+tqATV/org71vLM 6Ed2bWCLzECSu4JKiCb2Du8kUxFBW4VPLqD8Z058hKUPNLGmc6PZEWXUXZF3HAAdg4 Fres/tcWC+6kXssiXH5nPuwwD9mfghfoIGXDfpMyYhhKHkEih4FV5S8uzHNRNhFgTn 3U71I4ypcZOK0+itvSa5Xz2IRWnXk21gaQQH9OXaMH5vmXx1brmsFnSV/3KYTWPoXz Sq2GEQ4KQ38Ow== Date: Thu, 2 Jan 2025 14:36:47 -0800 From: Jakub Kicinski To: Antoine Tenart Cc: davem@davemloft.net, pabeni@redhat.com, edumazet@google.com, netdev@vger.kernel.org, gregkh@linuxfoundation.org, mhocko@suse.com, stephen@networkplumber.org Subject: Re: [RFC PATCH net-next 1/4] net-sysfs: remove rtnl_trylock from device attributes Message-ID: <20250102143647.7963cbfd@kernel.org> In-Reply-To: <20231018154804.420823-2-atenart@kernel.org> References: <20231018154804.420823-1-atenart@kernel.org> <20231018154804.420823-2-atenart@kernel.org> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Wed, 18 Oct 2023 17:47:43 +0200 Antoine Tenart wrote: > We have an ABBA deadlock between net device unregistration and sysfs > files being accessed[1][2]. To prevent this from happening all paths > taking the rtnl lock after the sysfs one (actually kn->active refcount) > use rtnl_trylock and return early (using restart_syscall)[3] which can > make syscalls to spin for a long time when there is contention on the > rtnl lock[4]. Hi Antoine! I was looking at the sysfs locking, and ended up going down a very similar path. Luckily lore search for sysfs_break_active_protection() surfaced this thread so I can save myself some duplicated work :) Is there any particular reason why you haven't pursued this solution further? I think it should work. My version, FWIW: https://github.com/kuba-moo/linux/commit/2724bb7275496a254b001fe06fe20ccc5addc9d2