systemctl命令timed out

问题描述：执行ps、reboot、shutdown命令卡住，无响应。systemctl命令会报timed out。导致无法重启机器。

• 使用journalctl -f命令查看systemd的日志，发现循环报出同一个错误“SLUB: Unable to allocate memory on node -1”；

Jun 17 22:22:44 m7-notebook-gpu01 kernel: SLUB: Unable to allocate memory on node -1 (gfp=0x20)
Jun 17 22:22:44 m7-notebook-gpu01 kernel:   node 1: slabs: 11, objs: 352, free: 0
Jun 17 22:22:44 m7-notebook-gpu01 kernel:   node 0: slabs: 8, objs: 256, free: 0
Jun 17 22:22:44 m7-notebook-gpu01 kernel:   cache: kmalloc-1024(9594:b6a598753d8c02d1281bd02f94591591ff9d5a2efbf24f43fa209dbca9136b84), object size: 1024, buffer size: 1024, default order: 3, min order: 0
Jun 17 22:22:44 m7-notebook-gpu01 kernel: SLUB: Unable to allocate memory on node -1 (gfp=0x20)
Jun 17 22:22:44 m7-notebook-gpu01 kernel:   node 1: slabs: 11, objs: 352, free: 0
Jun 17 22:22:44 m7-notebook-gpu01 kernel:   node 0: slabs: 8, objs: 256, free: 0
Jun 17 22:22:44 m7-notebook-gpu01 kernel:   cache: kmalloc-1024(9594:b6a598753d8c02d1281bd02f94591591ff9d5a2efbf24f43fa209dbca9136b84), object size: 1024, buffer size: 1024, default order: 3, min order: 0
Jun 17 22:22:44 m7-notebook-gpu01 kernel: SLUB: Unable to allocate memory on node -1 (gfp=0x20)
Jun 17 22:22:44 m7-notebook-gpu01 kernel:   node 1: slabs: 11, objs: 352, free: 0
Jun 17 22:22:44 m7-notebook-gpu01 kernel:   node 0: slabs: 8, objs: 256, free: 0
Jun 17 22:22:44 m7-notebook-gpu01 kernel:   cache: kmalloc-1024(9594:b6a598753d8c02d1281bd02f94591591ff9d5a2efbf24f43fa209dbca9136b84), object size: 1024, buffer size: 1024, default order: 3, min order: 0

• 查询后发现，添加交换分区可以解决该问题；https://stackoverflow.com/questions/43405813/linux-slub-unable-to-allocate-memory-on-node
• 使用mkswap命令设置交换分区；http://man.linuxde.net/mkswap
• 设置交换分区后，systemctl命令可以正常执行；