Michal Hocko wrote:
> @@ -563,6 +582,53 @@ static void wake_oom_reaper(struct task_struct *tsk)
> wake_up(&oom_reaper_wait);
> }
>
> +/* Check if we can reap the given task. This has to be called with stable
> + * tsk->mm
> + */
> +static void try_oom_reaper(struct task_struct *tsk)
> +{
> + struct mm_struct *mm = tsk->mm;
> + struct task_struct *p;
> +
> + if (!mm)
> + return;
> +
> + /*
> + * There might be other threads/processes which are either not
> + * dying or even not killable.
> + */
> + if (atomic_read(&mm->mm_users) > 1) {
> + rcu_read_lock();
> + for_each_process(p) {
> + bool exiting;
> +
> + if (!process_shares_mm(p, mm))
> + continue;
> + if (same_thread_group(p, tsk))
> + continue;
> + if (fatal_signal_pending(p))
> + continue;
> +
> + /*
> + * If the task is exiting make sure the whole thread group
> + * is exiting and cannot acces mm anymore.
> + */
> + spin_lock_irq(&p->sighand->siglock);
> + exiting = signal_group_exit(p->signal);
> + spin_unlock_irq(&p->sighand->siglock);
> + if (exiting)
> + continue;
> +
> + /* Give up */
> + rcu_read_unlock();
> + return;
> + }
> + rcu_read_unlock();
> + }
> +
> + wake_oom_reaper(tsk);
> +}
> +
I think you want to change "try_oom_reaper() without wake_oom_reaper()"
as mm_is_reapable() and use it from oom_kill_process() in order to skip
p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN test which needlessly makes
can_oom_reap false.
> @@ -694,6 +746,7 @@ void oom_kill_process(struct oom_control *oc, struct task_struct *p,
> task_lock(p);
> if (p->mm && task_will_free_mem(p)) {
> mark_oom_victim(p);
> + try_oom_reaper(p);
> task_unlock(p);
> put_task_struct(p);
> return;
> @@ -873,6 +926,7 @@ bool out_of_memory(struct oom_control *oc)
> if (current->mm &&
> (fatal_signal_pending(current) || task_will_free_mem(current))) {
> mark_oom_victim(current);
> + try_oom_reaper(current);
> return true;
> }
>
Why don't you call try_oom_reaper() from the shortcuts in
mem_cgroup_out_of_memory() as well?
Why don't you embed try_oom_reaper() into mark_oom_victim() like I did at
http://lkml.kernel.org/r/201602052014.HBG52666.HFMOQVLFOSFJtO@xxxxxxxxxxxxxxxxxxx ?
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