On 06/16, KOSAKI Motohiro wrote:
>
> Now, oom are using "child->mm != p->mm" check to distinguish subthread.
Heh. is it true??? I never undestood what oom_kill_process()->list_for_each_entry()
is supposed to do.
> But It's incorrect. vfork() child also have the same ->mm.
Yes.
> This patch change to use same_thread_group() instead.
I don't think we need same_thread_group(). Please note that any children must
be from the different thread_group.
So,
> --- a/mm/oom_kill.c
> +++ b/mm/oom_kill.c
> @@ -161,7 +161,7 @@ unsigned long oom_badness(struct task_struct *p, unsigned long uptime)
> list_for_each_entry(c, &t->children, sibling) {
> child = find_lock_task_mm(c);
> if (child) {
> - if (child->mm != p->mm)
> + if (same_thread_group(p, child))
> points += child->mm->total_vm/2 + 1;
> task_unlock(child);
> }
> @@ -486,7 +486,7 @@ static int oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
> list_for_each_entry(child, &t->children, sibling) {
> unsigned long child_points;
>
> - if (child->mm == p->mm)
> + if (same_thread_group(p, child))
> continue;
In both cases same_thread_group() must be false.
This means that the change in oom_badness() doesn't look right,
"child->mm != p->mm" is the correct check to decide whether we should
account child->mm.
The change in oom_kill_process() merely removes this "continue".
Could someone please explain what this code _should_ do?
Oleg.
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