Re: oops in proc_pid_stat() on task->real_parent?

[Chris Wright <chrisw@osdl.org>]

* Andrew Morton (akpm@osdl.org) wrote:
> Chris Wright <chrisw@osdl.org> wrote:
> >
> > * Andrew Morton (akpm@osdl.org) wrote:
> > > yup, we fixed that one.
> > 
> > I thought the same thing, but this oops is from proc_pid_stat, not
> > proc_pid_status.  The code is now in do_task_stat(), and the oops is
> > within the orignal tasklist lock (instead of dropping and reaquiring the
> > lock).  So, might be fixed, but if so, I think for a different reason.
> > 
> 
> Ah, thanks.
> 
> I'm not sure that the holding of tasklist_lock is going to save us there. 
> But then, Manfred recently did an audit, so I'm probably missing something.
> 
> Manfred, should we do this?

Yeah, I wondered the same.  Although I don't see why pid_alive() check
would be useful if it's the real_parent that's gone.  Dave mentioned
that he's got slab poisoning enabled, and the real_parent pointer was
valid (i.e. not 6b6b6b6b).  So wouldn't tasklist_lock serialize against
exiting real_parent?

thanks,
-chris
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