Question: How to switch a process namespace by nsfs "device" and inode number directly?

[Chengdong Li <chengdong.li@linux.alibaba.com>]

Hi folks,

I am getting stuck by the lack of approach to switch process namespace 
by nsfs "device" and inode number in user-space,  for example (mnt: 
0xf0000000)

 From my best understanding, the normal way to do that is by setns 
system call. But setns only accept fd that refer to a opened namespace, 
sometimes we couldn't get it.

For example:  After perf record, perf report couldn't work well once the 
process that runs inside a container has exited, as the /proc/pid/ns 
doesn't exist anymore after process exit.

Any comments are welcome!


Thanks,

Chengdong