On 04/08, David Rientjes wrote:
>
> On Thu, 1 Apr 2010, Oleg Nesterov wrote:
>
> > Look. We have a main thread M and the sub-thread T. T forks a lot of
> > processes which use a lot of memory. These processes _are_ the first
> > descendant children of the M+T thread group, they should be accounted.
> > But M->children list is empty.
> >
> > oom_forkbomb_penalty() and oom_kill_process() should do
> >
> > t = tsk;
> > do {
> > list_for_each_entry(child, &t->children, sibling) {
> > ... take child into account ...
> > }
> > } while_each_thread(tsk, t);
> >
>
> In this case, it seems more appropriate that we would penalize T and not M
We can't. Any fatal signal sent to any sub-thread kills the whole thread
group. It is not possible to kill T but not M.
> since it's not necessarily responsible for the behavior of the children it
> forks. T is the buggy/malicious program, not M.
Since a) they share the same ->mm and b) they share their children, I
don't think we should separate T and M.
->children is per_thread. But this is only because we have some strange
historiral oddities like __WNOTHREAD. Otherwise, it is not correct to
assume that the child of T is not the child of M. Any process is the
child of its parent's thread group, not the thread which actually called
fork().
> > --- x/mm/oom_kill.c
> > +++ x/mm/oom_kill.c
> > @@ -97,13 +97,16 @@ static unsigned long oom_forkbomb_penalt
> > return 0;
> > list_for_each_entry(child, &tsk->children, sibling) {
> > struct task_cputime task_time;
> > - unsigned long runtime;
> > + unsigned long runtime, this_rss;
> >
> > task_lock(child);
> > if (!child->mm || child->mm == tsk->mm) {
> > task_unlock(child);
> > continue;
> > }
> > + this_rss = get_mm_rss(child->mm);
> > + task_unlock(child);
> > +
> > /*
>
> This patch looks good, will you send it to Andrew with a changelog and
> sign-off line? Also feel free to add:
>
> Acked-by: David Rientjes <rientjes@xxxxxxxxxx>
Thanks! already in -mm.
Oleg.
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxxx For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>