Re: [PATCH 3/7] memcg: immigrate charges only when a threadgroup leader is moved

[Michal Hocko <mhocko@suse.cz>]

On Fri 22-05-15 20:30:42, Oleg Nesterov wrote:
> On 05/22, Michal Hocko wrote:
> >
> > On Fri 22-05-15 18:29:00, Oleg Nesterov wrote:
> > >
> > > In the likely case (if CLONE_VM without CLONE_THREAD was not used) the
> > > last for_each_process() in mm_update_next_owner() will find another thread
> > > from the same group.
> >
> > My understanding was that for_each_process will iterate only over
> > processes (represented by the thread group leaders).
> 
> Yes. But note the inner for_each_thread() loop. And note that we
> we need this loop exactly because the leader can be zombie.

I was too vague, sorry about that. What I meant was that
for_each_process would pick up a group leader and the inner
for_each_thread will return it as the first element in the list. As the
leader waits for other threads then it should stay on the thread_node
list as well. But I might be easily wrong here because the whole thing
is really quite confusing to be honest.
-- 
Michal Hocko
SUSE Labs

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