Hi Richard,
Sorry, I already forgot the context, not sure I understand your email
correctly.
On 12/16, Richard Guy Briggs wrote:
> On 13/08/26, Richard Guy Briggs wrote:
> > On Thu, Aug 22, 2013 at 09:08:48PM +0200, Oleg Nesterov wrote:
> > > On 08/20, Richard Guy Briggs wrote:
> > > >
> > > > static inline int is_global_init(struct task_struct *tsk)
> > > > {
> > > > - return tsk->pid == 1;
> > > > + return task_pid_nr(tsk) == 1;
> > > > }
> > >
> > > Probably it would be better to simply kill it. Almost every usage is
> > > wrong.
> >
> > Can you be more clear? I don't follow. It should instead return a
> > boolean. Usage of is_global_init() or task_pid_nr()?
> >
> > If is_global_init(), is that because they could be unaware of pid
> > namespaces?
> >
> > If task_pid_nr(), is that for the same reason?
>
> Oleg, I still don't understand your comment above. Kill what,
> "is_global_init()"? If so, how is almost every usage of it wrong?
Because is_global_init() is only true for the main thread of /sbin/init.
Just look at oom_unkillable_task(). It tries to not kill init. But, say,
select_bad_process() can happily find a sub-thread of is_global_init()
and still kill it.
> There are a number of functions that call is_global_init(). Might any
> of them be called from inside the namespace context of a container and
> hence should return true?
Not sure I understand, but certainly some callers should check ->child_reaper
or SIGNAL_UNKILLABLE instead. Say, unhandled_signal().
> > > > static inline bool is_idle_task(const struct task_struct *p)
> > > > {
> > > > - return p->pid == 0;
> > > > + return task_pid(p) == &init_struct_pid;
> > > > }
> > >
> > > hmm. there should be a simpler check for this...
> >
> > Other than the original, this one is pretty simple. What did you have
> > in mind?
>
> I vaguely remember a clarification to this, but don't remember and can't
> find it. What sort of simplification did you have in mind?
I do not remember ;) Most probably, I meant "it would be nice to find a
simpler check".
Oleg.
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