> > > > (3) oom_kill_task (when oom_kill_allocating_task==1 only)
> > > >
> > >
> > > Why would care about cpuset attachment in oom_kill_task()? You mean
> > > oom_kill_process() to filter the children list?
> >
> > Ah, intersting question. OK, we have to discuss oom_kill_allocating_task
> > design at first.
> >
> > First of All, oom_kill_process() to filter the children list and this issue
> > are independent and unrelated. My patch was not correct too.
> >
> > Now, oom_kill_allocating_task basic logic is here. It mean, if oom_kill_process()
> > return 0, oom kill finished successfully. but if oom_kill_process() return 1,
> > fallback to normall __out_of_memory().
> >
>
> Right.
>
> >
> > ===================================================
> > static void __out_of_memory(gfp_t gfp_mask, int order, nodemask_t *nodemask)
> > {
> > struct task_struct *p;
> > unsigned long points;
> >
> > if (sysctl_oom_kill_allocating_task)
> > if (!oom_kill_process(current, gfp_mask, order, 0, NULL, nodemask,
> > "Out of memory (oom_kill_allocating_task)"))
> > return;
> > retry:
> >
> > When oom_kill_process() return 1?
> > I think It should be
> > - current is OOM_DISABLE
>
> In this case, oom_kill_task() returns 1, which causes oom_kill_process()
> to return 1 if current (and not one of its children) is actually selected
> to die.
Right.
>
> > - current have no intersected CPUSET
>
> current will always intersect its own cpuset's mems.
Oops, It was my mistake.
>
> > - current is KTHREAD
>
> find_lock_task_mm() should take care of that in oom_kill_task() just like
> it does for OOM_DISABLE, although we can still race with use_mm(), in
> which case this would be a good chance.
find_lock_task_mm() implementation is here. it only check ->mm.
other place are using both KTHREAD check and find_lock_task_mm().
----------------------------------------------------------------------
/*
* The process p may have detached its own ->mm while exiting or through
* use_mm(), but one or more of its subthreads may still have a valid
* pointer. Return p, or any of its subthreads with a valid ->mm, with
* task_lock() held.
*/
static struct task_struct *find_lock_task_mm(struct task_struct *p)
{
struct task_struct *t = p;
do {
task_lock(t);
if (likely(t->mm))
return t;
task_unlock(t);
} while_each_thread(p, t);
return NULL;
}
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