ThinkPad W541（Ubuntu 20.04.6）下NetworkManager启动失败（核心转储）求助

我的问题背景 #

我用的是ThinkPad W541，装的Ubuntu 20.04.6，因为在ISP工作，平时经常要进「高级网络配置」编辑VLAN接口，这么操作快一年了都没出过问题。

前阵子把一个接口改成DHCP后重启生效，结果重启后GNOME桌面提示NetworkManager需要运行，但我卸载重装（purge后重新安装）、反复重启都没用，它就是启动失败，核心转储了。

当前NetworkManager状态输出：

● NetworkManager.service - Network Manager
Loaded: loaded (/lib/systemd/system/NetworkManager.service; enabled; vendo>
Active: failed (Result: core-dump) since Mon 2023-07-17 16:32:13 MDT; 32mi>
Docs: man:NetworkManager(8)
Process: 7383 ExecStart=/usr/sbin/NetworkManager --no-daemon (code=dumped, >
Main PID: 7383 (code=dumped, signal=SEGV)
lines 1-6/6 (END)

启动时的详细日志：

Jul 17 20:57:58 lacomputadoradecfiddy systemd[1]: Stopped Network Manager.
Jul 17 20:57:58 lacomputadoradecfiddy systemd[1]: Starting Network Manager...
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6696] NetworkManager (version 1.22.10) is starting... (after a restart)
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6696] Read config: /etc/NetworkManager/NetworkManager.conf (lib: 10-dns-resolved.conf>
Jul 17 20:57:58 lacomputadoradecfiddy systemd[1]: Started Network Manager.
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6714] bus-manager: acquired D-Bus service "org.freedesktop.NetworkManager"
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6735] manager[0x55a2a5c74040]: monitoring kernel firmware directory '/lib/firmware'.
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6735] monitoring ifupdown state file '/run/network/ifstate'.
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6746] hostname: hostname: using hostnamed
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6746] hostname: hostname changed from (none) to "lacomputadoradecfiddy"
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6748] dns-mgr[0x55a2a5c5f290]: init: dns=systemd-resolved rc-manager=symlink, plugin=>
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6755] rfkill2: found Wi-Fi radio killswitch (at /sys/devices/pci0000:00/0000:00:1c.1/>
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6757] manager[0x55a2a5c74040]: rfkill: Wi-Fi hardware radio set enabled
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6757] manager[0x55a2a5c74040]: rfkill: WWAN hardware radio set enabled
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6768] Loaded device plugin: NMWwanFactory (/usr/lib/x86_64-linux-gnu/NetworkManager/1>
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6776] Loaded device plugin: NMTeamFactory (/usr/lib/x86_64-linux-gnu/NetworkManager/1>
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6781] Loaded device plugin: NMBluezManager (/usr/lib/x86_64-linux-gnu/NetworkManager/>
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6785] Loaded device plugin: NMWifiFactory (/usr/lib/x86_64-linux-gnu/NetworkManager/1>
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6787] Loaded device plugin: NMAtmManager (/usr/lib/x86_64-linux-gnu/NetworkManager/1.>
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6791] manager: rfkill: Wi-Fi enabled by radio killswitch; enabled by state file
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6792] manager: rfkill: WWAN enabled by radio killswitch; enabled by state file
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6794] manager: Networking is enabled by state file
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6795] dhcp-init: Using DHCP client 'internal'
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6797] settings: Loaded settings plugin: ifupdown ("/usr/lib/x86_64-linux-gnu/NetworkM>
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6798] settings: Loaded settings plugin: keyfile (internal)
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6798] ifupdown: management mode: unmanaged
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6798] ifupdown:       interface-parser: parsing file /etc/network/interfaces
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6798] ifupdown:       interface-parser: source line includes interfaces file(s) /etc/>
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.6799] ifupdown:       interface-parser: finished parsing file /etc/network/interfaces
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.8376] device (lo): carrier: link connected
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.8379] manager: (lo): new Generic device (/org/freedesktop/NetworkManager/Devices/1)
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.8394] manager: (enp0s25): new Ethernet device (/org/freedesktop/NetworkManager/Device>
Jul 17 20:57:58 lacomputadoradecfiddy NetworkManager[1341]:   [1689649078.8403] device (enp0s25): state change: unmanaged -> unavailable (reason 'managed', sys>
Jul 17 20:57:59 lacomputadoradecfiddy systemd[1]: NetworkManager.service: Main process exited, code=dumped, status=11/SEGV
Jul 17 20:57:59 lacomputadoradecfiddy systemd[1]: NetworkManager.service: Failed with result 'core-dump'.
Jul 17 20:57:59 lacomputadoradecfiddy systemd[1]: NetworkManager.service: Scheduled restart job, restart counter is at 5.
Jul 17 20:57:59 lacomputadoradecfiddy systemd[1]: Stopped Network Manager.
Jul 17 20:57:59 lacomputadoradecfiddy systemd[1]: NetworkManager.service: Start request repeated too quickly.
Jul 17 20:57:59 lacomputadoradecfiddy systemd[1]: NetworkManager.service: Failed with result 'core-dump'.
Jul 17 20:57:59 lacomputadoradecfiddy systemd[1]: Failed to start Network Manager.

现在我能手动设置接口为DHCP，但这完全满足不了我日常工作的需求，有没有大佬能给点思路？

针对你的情况，试试这些排查和解决步骤： #

1. 检查/etc/network/interfaces配置文件

从日志里能看到NetworkManager在解析这个文件后没多久就崩溃了，大概率是这个文件里的VLAN配置有语法错误或者冲突。你可以先备份这个文件，然后暂时替换成默认内容试试：

sudo cp /etc/network/interfaces /etc/network/interfaces.bak
sudo echo -e "auto lo\niface lo inet loopback" > /etc/network/interfaces

然后重启NetworkManager服务：

sudo systemctl restart NetworkManager

如果能正常启动，说明就是原配置文件的问题，你可以慢慢对比备份文件，找出出错的VLAN配置项。

2. 分析核心转储文件，定位崩溃点

Ubuntu默认会生成核心转储，你可以用gdb来分析，看看NetworkManager到底在处理什么内容时崩溃：

sudo apt install gdb
sudo gdb /usr/sbin/NetworkManager /var/lib/systemd/coredump/core.NetworkManager.*

在gdb里输入bt查看调用栈，这样能精准定位到崩溃的模块，比如是不是某个VLAN相关的插件出问题了。

3. 重置NetworkManager的配置文件

有时候配置文件损坏也会导致崩溃，你可以重置NetworkManager的配置：

sudo systemctl stop NetworkManager
sudo rm -rf /etc/NetworkManager/system-connections/*
sudo rm -rf /var/lib/NetworkManager/*
sudo systemctl start NetworkManager

注意：这样会清除所有已保存的网络配置，你之后需要重新添加VLAN和接口信息，但能排除配置损坏的问题。

4. 检查并修复依赖包

可能是NetworkManager的依赖包损坏导致崩溃，试试重新安装所有相关依赖：

sudo apt install --reinstall network-manager network-manager-gnome
sudo apt-get -f install

5. 临时应急方案（如果以上都没效果）

如果急着用网络，你可以先禁用NetworkManager，改用systemd-networkd来管理网络，虽然操作麻烦点，但能满足你编辑VLAN的需求：

sudo systemctl stop NetworkManager
sudo systemctl disable NetworkManager
sudo systemctl enable systemd-networkd
sudo systemctl start systemd-networkd

然后在/etc/systemd/network目录下创建VLAN和接口的配置文件，比如VLAN 10的配置文件10-vlan10.netdev：

[NetDev]
Name=vlan10
Kind=vlan

[VLAN]
Id=10

再创建对应的IP配置文件20-vlan10.network：

[Match]
Name=vlan10

[Network]
DHCP=yes

重启systemd-networkd就能生效：

sudo systemctl restart systemd-networkd

6. 考虑升级或降级NetworkManager版本

Ubuntu 20.04的NetworkManager版本是1.22.10，可能这个版本存在已知的VLAN相关bug，你可以试试升级到backports里的新版本：

sudo add-apt-repository universe
sudo add-apt-repository ppa:ubuntu-backports/ppa
sudo apt update
sudo apt install network-manager -t focal-backports

如果升级后问题依旧，也可以尝试降级到之前的稳定版本。

备注：内容来源于stack exchange，提问作者Chris Foster