On Mon, Jun 21, 2010 at 08:45:45PM +0900, KOSAKI Motohiro wrote:
> > On Thu, 17 Jun 2010, KOSAKI Motohiro wrote:
> >
> > > When oom_kill_allocating_task is enabled, an argument task of
> > > oom_kill_process is not selected by select_bad_process(), It's
> > > just out_of_memory() caller task. It mean the task can be
> > > unkillable. check it first.
> > >
> >
> > This should be unnecessary if oom_kill_process() appropriately returns
> > non-zero when it cannot kill a task. What problem are you addressing with
> > this fix?
>
> oom_kill_process() only check its children are unkillable, not its own.
> To add check oom_kill_process() also solve the issue. as my previous patch does.
> but Minchan pointed out it's unnecessary. because when !oom_kill_allocating_task
> case, we have the same check in select_bad_process().
>
>
>
If kthread doesn't use other process's mm, oom_kill_process can return non-zero.
and it might be no problem.
but let's consider following case that kthread use use_mm.
if (oom_kill_allocating_task)
oom_kill_process
pr_err("kill process.."); <-- false alarm
oom_kill_task
find_lock_task_mm if kthread use use_mm
kill kernel thread
Yes. it's a just theory that kthread use use_mm and is selected as victim.
But although kthread doesn't use use_mm, oom_kill_process emits false alarm.
As a matter of fact, it doesn't kill itself or sacrifice child.
I think victim process selection should be done before calling
oom_kill_process. oom_kill_process and oom_kill_task's role is
just to try to kill the process or process's children by best effort
as function's name.
--
Kind regards,
Minchan Kim
--
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>