From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tommi Rantala Subject: sctp netns "unregister_netdevice: waiting for lo to become free. Usage count = 1" Date: Mon, 29 Jan 2018 17:55:45 +0200 Message-ID: <2a9c25b0-9ee7-baf6-f212-2c94b06941ea@nokia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit To: Vlad Yasevich , Neil Horman , linux-sctp@vger.kernel.org, "netdev@vger.kernel.org" Return-path: Received: from mail-eopbgr20113.outbound.protection.outlook.com ([40.107.2.113]:54625 "EHLO EUR02-VE1-obe.outbound.protection.outlook.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751829AbeA2Pzy (ORCPT ); Mon, 29 Jan 2018 10:55:54 -0500 Content-Language: en-US Sender: netdev-owner@vger.kernel.org List-ID: Hi, When running sctp_test from lksctp-tools in netns in 4.4 and 4.9 with suitable arguments, the local loopback device in the netns is not getting destroyed after deleting the netns. For example: ip netns add TEST ip netns exec TEST ip link set lo up ip link add dummy0 type dummy ip link add dummy1 type dummy ip link add dummy2 type dummy ip link set dev dummy0 netns TEST ip link set dev dummy1 netns TEST ip link set dev dummy2 netns TEST ip netns exec TEST ip addr add 192.168.1.1/24 dev dummy0 ip netns exec TEST ip link set dummy0 up ip netns exec TEST ip addr add 192.168.1.2/24 dev dummy1 ip netns exec TEST ip link set dummy1 up ip netns exec TEST ip addr add 192.168.1.3/24 dev dummy2 ip netns exec TEST ip link set dummy2 up ip netns exec TEST sctp_test -H 192.168.1.2 -P 20002 -h 192.168.1.1 -p 20000 -s -B 192.168.1.3 ip netns del TEST Results to: [ 354.179591] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 364.419674] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 374.663664] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 384.903717] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 395.143724] unregister_netdevice: waiting for lo to become free. Usage count = 1 [ 405.383645] unregister_netdevice: waiting for lo to become free. Usage count = 1 ... Based on a quick test, 4.14 and 4.15 does not suffer from this, but its reproducible e.g. in 4.4.113 and 4.9.75 Any ideas? Tommi