Re: [PATCH v10 1/2] /proc/PID/status: show all sets of pid according to ns

["Serge E. Hallyn" <serge@hallyn.com>]

On Mon, Feb 23, 2015 at 01:00:09PM -0800, Andrew Morton wrote:
> On Fri, 6 Feb 2015 18:45:49 +0800 Chen Hanxiao <chenhanxiao@cn.fujitsu.com> wrote:
> 
> > If some issues occurred inside a container guest, host user
> > could not know which process is in trouble just by guest pid:
> > the users of container guest only knew the pid inside containers.
> > This will bring obstacle for trouble shooting.
> > 
> > This patch adds four fields: NStgid, NSpid, NSpgid and NSsid:
> > a) In init_pid_ns, nothing changed;
> > 
> > b) In one pidns, will tell the pid inside containers:
> >   NStgid: 21776   5       1
> >   NSpid:  21776   5       1
> >   NSpgid: 21776   5       1
> >   NSsid:  21729   1       0
> >   ** Process id is 21776 in level 0, 5 in level 1, 1 in level 2.
> > 
> > c) If pidns is nested, it depends on which pidns are you in.
> >   NStgid: 5       1
> >   NSpid:  5       1
> >   NSpgid: 5       1
> >   NSsid:  1       0
> >   ** Views from level 1
> > 
> > ...
> >
> > --- a/fs/proc/array.c
> > +++ b/fs/proc/array.c
> > @@ -208,6 +208,22 @@ static inline void task_state(struct seq_file *m, struct pid_namespace *ns,
> >  			   from_kgid_munged(user_ns, GROUP_AT(group_info, g)));
> >  	put_cred(cred);
> >  
> > +	seq_puts(m, "\nNStgid:");
> > +	for (g = ns->level; g <= pid->level; g++)
> > +		seq_printf(m, "\t%d",
> > +			task_tgid_nr_ns(p, pid->numbers[g].ns));
> > +	seq_puts(m, "\nNSpid:");
> > +	for (g = ns->level; g <= pid->level; g++)
> > +		seq_printf(m, "\t%d",
> > +			task_pid_nr_ns(p, pid->numbers[g].ns));
> > +	seq_puts(m, "\nNSpgid:");
> > +	for (g = ns->level; g <= pid->level; g++)
> > +		seq_printf(m, "\t%d",
> > +			task_pgrp_nr_ns(p, pid->numbers[g].ns));
> > +	seq_puts(m, "\nNSsid:");
> > +	for (g = ns->level; g <= pid->level; g++)
> > +		seq_printf(m, "\t%d",
> > +			task_session_nr_ns(p, pid->numbers[g].ns));
> >  	seq_putc(m, '\n');
> >  }
> 
> Is there any point in including this code if CONFIG_USER_NS=n?

Not if CONFIG_PID_NS=n, no