From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=209.85.128.178 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794397109; b=WJ7srcWRvGXCFDEws4DFJHGimXXhwe3LcZQshAeeemvwX52f2Z3ahTvRCSenu6wjzJhh 0clUdBZfMRp6scaEuwnuIudgtxOTUXk2VxeuVMi8WCfZT5l9aCYTRSoXo7E8QhW5WpGuK 1/mQzPIhf2rSNhUqr2C8pR+Igz2uTLzTSLEYqN9AlJbxPnOFOyavvZPm6X/pv1vKHRml1 7ZXj/YAiU+jGXGitX3WjZrAWqU/dEdN4KbrXG5D3ZTOsFQI7oE9cBYDqkmqIjBEP2tBrx 4UDFfqzLpW5giKOEKcfg16N+YKbthKOnpTnz03yUAmtf935M/3jNcVGQNoEy/ut1yMQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794397109; h=DMARC-Filter:Received:DKIM-Signature:X-Google-DKIM-Signature: X-Forwarded-Encrypted:X-Gm-Message-State:X-Gm-Gg:X-Received:Received: From:To:Cc:Subject:Date:Message-ID:X-Mailer:In-Reply-To:References: MIME-Version:Content-Transfer-Encoding; bh=4fTSg96yjoQMA+V2VPZldNNXe6tjLZP6OX5IOcXamiY=; b=ZU6V2lcj4CpgV8RjM8VxUWqRg/5SZ+rMe5IJuO0gMridoFy14SNS1R+RD7jPwGfoSqZo 9XdaBcBMCZ9Zm0gVevRCZCSjbvzPd70+FZuuz5St7vCVaHr1Yosh0jBMCgAlUNQ8SQMo8 deGAJLFqUTxPBImsfn6rtMZO8T1dYY3AY3UF83P2b9muTIoXxdCxqE5F8XHdsLWqZ0zjK vhSMgCE1bKw6BMoj232wb/Mqg2fSeXSq0fHlPJVU3phbN7JGTZe3mOmLfOfirlQx5fOsG oAFeHUNXRuxMTlsmoMO6jYrLwzpJi8WY/2tz4Ajkw7nJh8HICIWeEuwOQvcbWfkphkw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b="vB/q3lbx"; arc=none smtp.remote-ip=209.85.128.178 Received: from mail-yw1-f178.google.com (mail-yw1-f178.google.com [209.85.128.178]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A92EC606A32D for ; Wed, 11 Nov 2026 11:38:28 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org A92EC606A32D Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256 header.s=20260707 header.b=vB/q3lbx Received: by mail-yw1-f178.google.com with SMTP id 00721157ae682-8b31ca7e0bcso34030137b3.0 for ; Wed, 11 Nov 2026 03:38:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20260707; t=1794397107; x=1795001907; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=4fTSg96yjoQMA+V2VPZldNNXe6tjLZP6OX5IOcXamiY=; b=vB/q3lbxzaYlSJ1+gXxktaNt86Jwvfy2jDt2MT+T7mKBFdt7mmeMZ53iEjIWNJFvHh IIZL0qdkYyYYgN57HQSKr33WHgMlUF00IUwe1XHSHzeZ0vQeq04AS/NPTTYTwXteT5k3 oE04k47YKh3Ia+VqASIpobwla8xPQLSOThYuRjlsz7yg9lDbex7XBYVdr79DdDVBsJ0W +XecGUII5mlSenRVyIIkho2Z+Sg6AHHqWpl5E/qPGEydBtWPi/CySJkw4iUku8AJ8nqX 3WpXH9hJEeg0qlAjq8gHoZDIvG2F7EpEqpUL31L7CafO6HFFbIROu7KCecTxOatcMbPy hMDw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20260707; t=1794397107; x=1795001907; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=4fTSg96yjoQMA+V2VPZldNNXe6tjLZP6OX5IOcXamiY=; b=FhkK8TAuJBLfu6/h75Zs4CXATlKrNpekAZ1dgSWUJ44hUQhePps5OL9QpKV+0i/tpb LNu5JL8I5mcpIKxDvewmpwdhf4L/2kmKi+NtUQWLynlck0LAW0Z6B0/UwAPhs2T3bv8y ng0jmqQJxG54bPeEPHDcd7Ce5zelwCCsnGPJ9K0/1gbOhhE8NGexw5Mhn1WJ5OKyw5PA rzM0I4YoKGRGNTQPuRS6MRZ+0bdlevgO44Sr6uw3P4Da2zOs5nN05hcpoxEKKss6wjXh hNWOwLb+MmXLKjj4V19gN+R6tyW54tsVgKy5ZER5jSTBh8zPPGxuPR1B6WI7r6/bR3WD DQFQ== X-Forwarded-Encrypted: i=1; AL+hErEeTPXCvC0kEMn7q+VnlpMSBzPIvYPlyDJYeOZ5j9JCPrgo8f+0Zaww9s9S22NTeR5ZLcBFo6EFI/FbNCA=@vger.kernel.org X-Gm-Message-State: APuU4Z8YkYEIvoRJAUPuiXT2USfSkirYoS8Zq9JbyRcqViHLVCRBQxL4 el2XOxg+PD9y+2Nw+zO6nspTxFjIpp/1SQxhVTl3gvqnzYF8hMsW6J3r X-Gm-Gg: AYBFou3ReawOqacl2QBRVO0VLF0O8OPVORj616wZHcpPPmJ9EqBtXjc1KNOhxASsXbM YR+G88lRwsh2Gv6dPEx1JvniFXR+r3/LduxGSSixzTLDG/AkykpKpACk2io1UwXnoVSnHYm5MW3 WF0yZ3Dgirgiqc/r935oo8CZROqGaf1L0lKpUyIoqzbWwe1WGq6QXb68DdjMsH4pnLhHKru0+E0 ernepZ24cpJ8RTdo6G0xg0E7wlb3ne0iP5Mor8WTCMLeZHhkQB+BGvinDwmUwSsWL6XcT/xhPo7 Gyw0RTSPXMfioKboeaXG2sfDcCCgjNokBFCIoqW77DSWiesvpfBPDwsy0ViLDtNpzQud7lQUCzP ZYuAJB/J7tVNrgSb6YHAzyEHg6mzOzuyWj0KveifyzwQUP4WVgvqrr2NDOwG8wI/0V+ldQF8X97 0nJOWibHm4HcmtX9906UQSSkgP/Mj6951LPWgIt93o8nCuNGihDiZ0wlOPZgsQH49f7Of/Ue4l5 vUFBrKwvCX0Dy0axEM1Zg9wDLLbAIjJp+p2uACK5tPUteBbTc2HsVXycAG5TbomgxCD/harkoiK 4CQ8nQQ41K/6nxFDtVMfg/ApUJ8aP0hOQCPFNEap3hLbRJtHxPHItmr7zP1w5vRyvtvHf6EQhm2 vUQSVkv1B X-Received: by 2002:a05:690c:15:b0:8b0:d9ff:4f74 with SMTP id 00721157ae682-8b3a81ce1b9mr20456647b3.42.1794397107526; Wed, 11 Nov 2026 03:38:27 -0800 (PST) Received: from fedora ([187.120.157.132]) by smtp.gmail.com with ESMTPSA id 00721157ae682-8b393426f13sm42133187b3.34.2026.11.11.03.38.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Nov 2026 03:38:27 -0800 (PST) From: Guilherme Giacomo Simoes To: trintaeoitogc@gmail.com Cc: axboe@kernel.dk, bvanassche@acm.org, josef@toxicpanda.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, nbd@other.debian.org, syzbot+d7d72f3d467710442af0@syzkaller.appspotmail.com Subject: Re: [PATCH] nbd: fix circular lock dependency Date: Wed, 11 Nov 2026 08:38:14 -0300 Message-ID: <20261111113814.221685-1-trintaeoitogc@gmail.com> X-Mailer: git-send-email 2.52.0 In-Reply-To: <20261111101919.215767-1-trintaeoitogc@gmail.com> References: <20261111101919.215767-1-trintaeoitogc@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Guilherme Giacomo Simoes wrote: > > There is no real circular lock dependency here. This patch addresses a > > lockdep false positive caused by the missing socket reclassification in > > the reconnect path. Please change the subject into something like > > "nbd: Also reclassify sockets in the reconnect path". > > > > > instead of the NBD-specific class leading to a possible lock dependency. > > > > Please change "possible lock dependency" into "lockdep false positive". > > > > > Reported-by: syzbot+d7d72f3d467710442af0@syzkaller.appspotmail.com > > > Link: https://syzkaller.appspot.com/bug?extid=d7d72f3d467710442af0 > > > > Please use Closes: instead of Link: for the syzbot report. > Ok, I will send a V2 What do you think: ``` nbd: must reclassify socket when socket is created When we need to connect or reconnect a new socket, we need to call nbd_reclassify_socket() to ensure that a false positive lock_dep circular warning fires. Inside nbd_add_socket(), after nbd_get_socket() call he already call nbd_reclassify_socket(). However inside nbd_genl_reconnect_sock_cb() the nbd_reclassify_socket() must be called too and this is not doing. To ensure that even when nbd_get_socket() is called the nbd_reclassify_socket() will be called to, put the nbd_reclassify_socket() inside nbd_get_socket(). Move the nbd_get_socket() bellow of nbd_reclassify_socket(). nbd_add_socket() no longer needs to do it. ``` ? > > If the reclassification should happen in nbd_get_socket(), please move > > nbd_reclassify_socket() up instead of moving nbd_get_socket() down. > I was have moved nbd_reclassify_socket up, just like you suggested, but git > don't understanded this very well. But I will find way to get it No , I couldn't do it :( thanks, Guilherme