exception about Kernel Panic // dirperm1 breaks the protection by the permission bits on the lower branch

问题描述：

1. K8S集群有一个worker，经常磁盘满，然后导致服务异常。

2. 查看/var/log/syslog， 发现非常多的异常如下：

1568405.455565] docker0: port 2(vethfd09262) entered forwarding state
[1568490.807194] aufs au_opts_verify:1612:docker[22618]: dirperm1 breaks the protection by the permission bits on the lower branch
[1568490.839695] aufs au_opts_verify:1612:docker[25041]: dirperm1 breaks the protection by the permission bits on the lower branch

3. 从/var/log/kern.log中查到以下异常：

SLUB: Unable to allocate memory on node -1 (gfp=0x2080020)
Mar 31 18:52:08 AQA-Worker-CLD kernel: [292333.759874] cache: nf_conntrack_12(1847:58cc5f8478f68d01290885da9a59e974cf0d4575d5b92047bea0c7fd5f82130f), object size: 312, buffer size: 320, default order: 1, min order: 0

原因：

AUFS不稳定,导致docker删除instance的时候不能正常删除，从docker ps上看container已经删除掉了，但系统资源并没有释放，导致磁盘使用持续上升。

参考：https://codeday.me/bug/20181115/395036.html

docker info

Containers: 0
Images: 0
Storage Driver: aufs
 Backing Filesystem: xfs
 Supports d_type: true
 Native Overlay Diff: true
<output truncated>

解决方法：

1. sudo systemctl stop docker

2. mv  /var/lib/docker /var/lib/docker.bk

3. vim /etc/docker/daemon.json

{
  "storage-driver": "overlay2"
}
4. systemctl restart docker 
5. docker info :

Containers: 0
Images: 0
Storage Driver: overlay2
 Backing Filesystem: xfs
 Supports d_type: true
 Native Overlay Diff: true
<output truncated>

参考：https://docs.docker.com/storage/storagedriver/overlayfs-driver/