From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from szxga01-in.huawei.com (szxga01-in.huawei.com [45.249.212.187]) (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 18C872C0F87; Wed, 13 Aug 2025 01:09:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.187 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755047395; cv=none; b=DJM9H7cKWlN1pvkAq6NMGmOIixK02SwMBQePzIeMp34l8PYMLFHDx+tj7t/tZvHdS3rnoOFwVofCXQSxzjHgXlfS17csAR4oD7wvdcCXJXdTUEPGxkgwEwXDbvePBUbZB4ga9Bku6V19Ka5ZHmAGriYKLrD2OJrZjGnVQ9AGkQ8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755047395; c=relaxed/simple; bh=Dp2TFP6knBwgB8NLhqQXcsYqaD8uvln3PQSjEoxzmkI=; h=Message-ID:Date:MIME-Version:Subject:To:CC:References:From: In-Reply-To:Content-Type; b=vDjxQFEo3Ohm4Is0oKAXtmkCYLLUYdWRypw3Ce2A41Pi9wwOsHrbt0QFDRcuK6TJblz2cVY5IuxrLpxd8FB3ukJZ9VQLFLAf8FFiCJnTlCZxqn1vnWdTDMtWIS7Ye922ZL5Yb6y5c7uZ0Qyq0p81lRv52R9CVICEvudP7mf4iAs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com; spf=pass smtp.mailfrom=huawei.com; arc=none smtp.client-ip=45.249.212.187 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=huawei.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huawei.com Received: from mail.maildlp.com (unknown [172.19.88.194]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4c1qvP6d1gz13N3g; Wed, 13 Aug 2025 09:06:25 +0800 (CST) Received: from dggpemf500016.china.huawei.com (unknown [7.185.36.197]) by mail.maildlp.com (Postfix) with ESMTPS id AA91814027A; Wed, 13 Aug 2025 09:09:49 +0800 (CST) Received: from [10.174.176.70] (10.174.176.70) by dggpemf500016.china.huawei.com (7.185.36.197) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1544.11; Wed, 13 Aug 2025 09:09:48 +0800 Message-ID: <3a6a930b-8d5d-4323-a71d-d7b0883a7527@huawei.com> Date: Wed, 13 Aug 2025 09:09:46 +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: [PATCH net v2] net: bridge: fix soft lockup in br_multicast_query_expired() To: Ido Schimmel CC: , , , , , , , , , , References: <20250812091818.542238-1-wangliang74@huawei.com> From: Wang Liang In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-ClientProxiedBy: kwepems200002.china.huawei.com (7.221.188.68) To dggpemf500016.china.huawei.com (7.185.36.197) 在 2025/8/12 14:10, Ido Schimmel 写道: > On Tue, Aug 12, 2025 at 05:18:18PM +0800, Wang Liang wrote: >> When set multicast_query_interval to a large value, the local variable >> 'time' in br_multicast_send_query() may overflow. If the time is smaller >> than jiffies, the timer will expire immediately, and then call mod_timer() >> again, which creates a loop and may trigger the following soft lockup >> issue. >> >> watchdog: BUG: soft lockup - CPU#1 stuck for 221s! [rb_consumer:66] >> CPU: 1 UID: 0 PID: 66 Comm: rb_consumer Not tainted 6.16.0+ #259 PREEMPT(none) >> Call Trace: >> >> __netdev_alloc_skb+0x2e/0x3a0 >> br_ip6_multicast_alloc_query+0x212/0x1b70 >> __br_multicast_send_query+0x376/0xac0 >> br_multicast_send_query+0x299/0x510 >> br_multicast_query_expired.constprop.0+0x16d/0x1b0 >> call_timer_fn+0x3b/0x2a0 >> __run_timers+0x619/0x950 >> run_timer_softirq+0x11c/0x220 >> handle_softirqs+0x18e/0x560 >> __irq_exit_rcu+0x158/0x1a0 >> sysvec_apic_timer_interrupt+0x76/0x90 >> >> >> This issue can be reproduced with: >> ip link add br0 type bridge >> echo 1 > /sys/class/net/br0/bridge/multicast_querier >> echo 0xffffffffffffffff > >> /sys/class/net/br0/bridge/multicast_query_interval >> ip link set dev br0 up >> >> The multicast_startup_query_interval can also cause this issue. Similar to >> the commit 99b40610956a("net: bridge: mcast: add and enforce query interval > ^ missing space > >> minimum"), add check for the query interval maximum to fix this issue. >> >> Link: https://lore.kernel.org/netdev/20250806094941.1285944-1-wangliang74@huawei.com/ >> Fixes: 7e4df51eb35d ("bridge: netlink: add support for igmp's intervals") > Probably doesn't matter in practice given how old both commits are, but > I think you should blame d902eee43f19 ("bridge: Add multicast > count/interval sysfs entries") instead. The commit message also uses the > sysfs path and not the netlink one. Thanks for your suggestions! The bug fix tag is really important. I will correct it and send a new patch later. >> Suggested-by: Nikolay Aleksandrov >> Signed-off-by: Wang Liang > Code looks fine to me.