Re: pivot_root. unmount old root

[Stephen Powell <zlinuxman@wowway.com>]

On Sun, 21 Mar 2010 09:38:12 -0400 (EDT), Katharina Haselhorst wrote:
> Since I'm doing a pivot_root before trying to umount the old root there 
> are still several processes keeping some files open inside the old root 
> subdirs. Init is still running, als well as rc and one shutdown script 
> (atm I'm doing the pivot_root just before shutdown, because most 
> processes are terminted by the time). If I kill one of these processes, 
> the systems gets shut down.
> I don't understand why there is still that shutdown script running, 
> because I'm doing a exec chroot. The pivot_root's manual says:  "Note 
> that exec chroot changes the running executable, which is necessary if 
> the  old root  directory  should be unmounted afterwards."
> And the init process is always running, so how does pivot_root handle 
> the open files of init?
> I did move the /proc and /dev mountpoints from old-root to the new root 
> - might that cause some problems? If I don't do that - lsof or fuser of 
> course don't show any open files for old-root, but I'm not able to 
> unmount to old-root either.

Maybe it's time to step back and ask a more basic question.
What is it that you are trying to accomplish?  I know that you are trying
to do a pivot_root.  But *why* are you trying to do a pivot_root?
Why do you think you need to do it?  What is the real-world problem
that you are trying to solve?

-- 
  .''`.     Stephen Powell    <zlinuxman@wowway.com>
 : :'  :
 `. `'`
   `-