From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out30-130.freemail.mail.aliyun.com (out30-130.freemail.mail.aliyun.com [115.124.30.130]) (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 E2C0BBA42; Tue, 10 Sep 2024 05:55:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.130 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725947718; cv=none; b=uWjbViT0hW/IaCXYkoRvXJu4uEwxejXAz1qu51Zxr2tPs3aYpu8L0COXKTKPtPBFg1DSp0yVeo90Afou/yGDXzhW8PmxeXvNFhxFz0nwYtYUqRhQa02Zg/TQSw6ecQJuXzQI7KosqR4ym5HQNk9hKrNG1m5LfziwP/JC33WWnyY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1725947718; c=relaxed/simple; bh=jCMOo32aAOxhSAoezhGNiFwU189v3QtxX0IEdyDCFu0=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=V9DP1zY08w5fDL036pqdX7qXHtA+ebnbxiPwnx3UXBC4A9xaNkCV7i0xBvxub3OPhosVe0iVF0cwZ2mBqYglMhWp6oODudaZqyYo+ZeJM/zSe9h3DrE7tGiltSlAFbEnZwGsDp8ahaCx0DoID2r4C6fYe4LAt8BdE8eZBopGCVY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=XR0Ahpgr; arc=none smtp.client-ip=115.124.30.130 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="XR0Ahpgr" DKIM-Signature:v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1725947707; h=Message-ID:Date:MIME-Version:Subject:To:From:Content-Type; bh=Q0yviRGBPKBitFi3hppGbYn4wyovmBxnZN0o6fY+fTo=; b=XR0AhpgrPGx+V5N9odCp8VPNAGsnAdtUj3PhGllWurwvFAQ8nUn1BHt70F/ddcfaAWe6lVgWNqTWnHGfbJuSD0bss4SgmRcochoFQ6xzHfBOqLbNyd9a9VOoXcwWCFmUdWQ5N4l2yciWEZLQBKtWzIN1XH1oVhDmF4QRex/nbOw= Received: from 30.221.149.60(mailfrom:alibuda@linux.alibaba.com fp:SMTPD_---0WEj560t_1725947705) by smtp.aliyun-inc.com; Tue, 10 Sep 2024 13:55:06 +0800 Message-ID: <02634384-2468-4598-b64a-0f558730c925@linux.alibaba.com> Date: Tue, 10 Sep 2024 13:55:05 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [syzbot] [net?] possible deadlock in rtnl_lock (8) To: Wenjia Zhang , Eric Dumazet , syzbot , Dust Li Cc: davem@davemloft.net, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, pabeni@redhat.com, syzkaller-bugs@googlegroups.com References: <0000000000000311430620013217@google.com> <0000000000005d1b320621973380@google.com> <17dc89d6-5079-4e99-9058-829a07eb773f@linux.ibm.com> Content-Language: en-US From: "D. Wythe" In-Reply-To: <17dc89d6-5079-4e99-9058-829a07eb773f@linux.ibm.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 9/9/24 7:44 PM, Wenjia Zhang wrote: > > > On 09.09.24 10:02, Eric Dumazet wrote: >> On Sun, Sep 8, 2024 at 10:12 AM syzbot >> wrote: >>> >>> syzbot has found a reproducer for the following issue on: >>> >>> HEAD commit:    df54f4a16f82 Merge branch 'for-next/core' into >>> for-kernelci >>> git tree: >>> git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git >>> for-kernelci >>> console output: >>> https://syzkaller.appspot.com/x/log.txt?x=12bdabc7980000 >>> kernel config: >>> https://syzkaller.appspot.com/x/.config?x=dde5a5ba8d41ee9e >>> dashboard link: >>> https://syzkaller.appspot.com/bug?extid=51cf7cc5f9ffc1006ef2 >>> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils >>> for Debian) 2.40 >>> userspace arch: arm64 >>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1798589f980000 >>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10a30e00580000 >>> >>> Downloadable assets: >>> disk image: >>> https://storage.googleapis.com/syzbot-assets/aa2eb06e0aea/disk-df54f4a1.raw.xz >>> vmlinux: >>> https://storage.googleapis.com/syzbot-assets/14728733d385/vmlinux-df54f4a1.xz >>> kernel image: >>> https://storage.googleapis.com/syzbot-assets/99816271407d/Image-df54f4a1.gz.xz >>> >>> IMPORTANT: if you fix the issue, please add the following tag to the >>> commit: >>> Reported-by: syzbot+51cf7cc5f9ffc1006ef2@syzkaller.appspotmail.com >>> >>> ====================================================== >>> WARNING: possible circular locking dependency detected >>> 6.11.0-rc5-syzkaller-gdf54f4a16f82 #0 Not tainted >>> ------------------------------------------------------ >>> syz-executor272/6388 is trying to acquire lock: >>> ffff8000923b6ce8 (rtnl_mutex){+.+.}-{3:3}, at: rtnl_lock+0x20/0x2c >>> net/core/rtnetlink.c:79 >>> >>> but task is already holding lock: >>> ffff0000dc408a50 (&smc->clcsock_release_lock){+.+.}-{3:3}, at: >>> smc_setsockopt+0x178/0x10fc net/smc/af_smc.c:3064 >>> >>> which lock already depends on the new lock. >>> I have noticed this issue for a while, but I question the possibility of it. If I understand correctly, a deadlock issue following is reported here: #2 lock_sock_smc {     clcsock_release_lock            --- deadlock     {     } } #1 rtnl_mutex {     lock_sock_smc     {     } } #0 clcsock_release_lock {     rtnl_mutex                      --deadlock     {     } } This is of course a deadlock, but #1 is suspicious. How would this happen to a smc sock? #1 ->        lock_sock_nested+0x38/0xe8 net/core/sock.c:3543        lock_sock include/net/sock.h:1607 [inline]        sockopt_lock_sock net/core/sock.c:1061 [inline]        sockopt_lock_sock+0x58/0x74 net/core/sock.c:1052        do_ip_setsockopt+0xe0/0x2358 net/ipv4/ip_sockglue.c:1078        ip_setsockopt+0x34/0x9c net/ipv4/ip_sockglue.c:1417        raw_setsockopt+0x7c/0x2e0 net/ipv4/raw.c:845        sock_common_setsockopt+0x70/0xe0 net/core/sock.c:3735        do_sock_setsockopt+0x17c/0x354 net/socket.c:2324 As a comparison, the correct calling chain should be:        sock_common_setsockopt+0x70/0xe0 net/core/sock.c:3735        smc_setsockopt+0x150/0xcec net/smc/af_smc.c:3072        do_sock_setsockopt+0x17c/0x354 net/socket.c:2324 That's to say,  any setting on SOL_IP options of smc_sock will go with smc_setsockopt, which will try lock clcsock_release_lock at first. Anyway, if anyone can explain #1, then we can see how to solve this problem, otherwise I think this problem doesn't exist. (Just my opinion) Best wishes, D. Wythe