Re: Q: cgroup: Questions about possible issues in cgroup locking

[Oleg Nesterov]

On 01/19, Mandeep Singh Baines wrote:
>
> Oleg Nesterov (oleg@xxxxxxxxxx) wrote:
> > But we did
> > have a reason (reasons?). Hopefully, the only really important reason
> > was already removed by 087806b1.
>
> Ah. So the leader->group_leader may have been necessary earlier in order
> to prevent two tasks, old leader and new leader from both returning true
> for thread_group_leader(tsk).

Not really. de_thread() does release_task(old_leader). Please look, for
example, at __exit_signal(). thread_group_leader() must not be true in
this case.

Oleg.

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