Re: [RFC] Add option to mount only a pids subset

[Alexey Gladkov <gladkov.alexey-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On Sun, Mar 26, 2017 at 09:03:33AM +0200, Djalal Harouni wrote:
> (Cc'ed Kees and Jann for the procfs stacking issue)
> 
> > I completely agree with you that it looks wrong when options of one
> > mountpoint affect the others mountpoints.
> >
> >> I'm not sure if that's the right approach, it is still buggy, however
> >> seems that your patch also stores the mount option inside the
> >> pid_namespace which may get propagated to all mounts inside same pidns
> >> ?
> >
> > I don't store 'pidonly' option in my current patch. I mean in:
> > https://lkml.org/lkml/2017/3/20/363
> >
> > I parse options twice at first mount of procfs. It happens before
> > the mounting /proc in userspace.
> >
> > I know it's bad, but I couldn't find place to store this option.
> 
> Ok, then maybe that approach of having a procfs struct holder instead
> of using pid namespace may help!

I deside to stop doing my patch. I talked with a few people and found out
that the overlayfs doesn't feel very well if on the lower level filesystem
appear/disappear files.

In addition with the pidfs isn't so simple. Separate the root will lead to
a doubling of memory consumption and restrictions on the filesystem operations
level can easily be skipped.

It means that even I can do this pidfs (or pid subset in /proc), it
will be pointless.

-- 
Rgrds, legion