Hello Yang Bo,

On 9/19/19 4:38 AM, Yang Bo wrote:

The man page says that new_root does not have be a mountpoint
but it must be, I tried to pivot_root into a non-mountpoint
directory and always failed with EINVAL, the kernel source
fs/namespace.c confirms that, to quote a comment from this file:

- it's okay to pick a root that isn't the root of a file system, e.g.
- /nfs/my_root where /nfs is the mount point. It must be a mountpoint,
- though, so you may need to say mount --bind /nfs/my_root /nfs/my_root
- first.

Yes, you are correct. There are in fact many problems in the
current pivot_root(2) page, and I am in the process of 
substantially revising it.

Thanks

Michael


-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/