On Thu, Aug 10, 2023 at 1:13 AM Chuyi Zhou <zhouchuyi@xxxxxxxxxxxxx> wrote:
> static int oom_evaluate_task(struct task_struct *task, void *arg)
> {
> struct oom_control *oc = arg;
> @@ -317,6 +339,26 @@ static int oom_evaluate_task(struct task_struct *task, void *arg)
> if (!is_memcg_oom(oc) && !oom_cpuset_eligible(task, oc))
> goto next;
>
> + /*
> + * If task is allocating a lot of memory and has been marked to be
> + * killed first if it triggers an oom, then select it.
> + */
> + if (oom_task_origin(task)) {
> + points = LONG_MAX;
> + goto select;
> + }
> +
> + switch (bpf_oom_evaluate_task(task, oc)) {
> + case BPF_EVAL_ABORT:
> + goto abort; /* abort search process */
> + case BPF_EVAL_NEXT:
> + goto next; /* ignore the task */
> + case BPF_EVAL_SELECT:
> + goto select; /* select the task */
> + default:
> + break; /* No BPF policy */
> + }
> +
I think forcing bpf prog to look at every task is going to be limiting
long term.
It's more flexible to invoke bpf prog from out_of_memory()
and if it doesn't choose a task then fallback to select_bad_process().
I believe that's what Roman was proposing.
bpf can choose to iterate memcg or it might have some side knowledge
that there are processes that can be set as oc->chosen right away,
so it can skip the iteration.
