Re: [PATCH 10/10] mm, oom: hide mm which is shared with kthread or global init

[Oleg Nesterov]

Michal,

I am going to ack the whole series, but send some nits/questions,

On 06/09, Michal Hocko wrote:
>
> @@ -283,10 +283,22 @@ enum oom_scan_t oom_scan_process_thread(struct oom_control *oc,
>  
>  	/*
>  	 * This task already has access to memory reserves and is being killed.
> -	 * Don't allow any other task to have access to the reserves.
> +	 * Don't allow any other task to have access to the reserves unless
> +	 * the task has MMF_OOM_REAPED because chances that it would release
> +	 * any memory is quite low.
>  	 */
> -	if (!is_sysrq_oom(oc) && atomic_read(&task->signal->oom_victims))
> -		return OOM_SCAN_ABORT;
> +	if (!is_sysrq_oom(oc) && atomic_read(&task->signal->oom_victims)) {
> +		struct task_struct *p = find_lock_task_mm(task);
> +		enum oom_scan_t ret = OOM_SCAN_ABORT;
> +
> +		if (p) {
> +			if (test_bit(MMF_OOM_REAPED, &p->mm->flags))
> +				ret = OOM_SCAN_CONTINUE;
> +			task_unlock(p);

OK, but perhaps it would be beter to change oom_badness() to return zero if
MMF_OOM_REAPED is set?

Oleg.