Re: [PATCH] task: Make task list manipulations RCU safe.

[Oleg Nesterov]

"Eric W. Biederman" wrote:
> 
> Oleg Nesterov <oleg@xxxxxxxxxx> writes:
> 
> > Some questions.
> >
> > first_tgid:
> >       ...
> >       for (; pos && pid_alive(pos); pos = next_task(pos))
> >
> > I think this patch makes this 'pid_alive(pos)' unneeded?
> 
> Close.  The problem is that we could have slept with the
> count elevated on start before we do rcu_read_lock().

Yes, we could have slept. But (unlike next_tgid) this loop
starts from pos=init_task or from pos=find_task_by_pid()
and we are doing find_task_by_pid under rcu_read_lock() ?

Oleg.
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