On Thu, Aug 5, 2021 at 11:40 PM Michal Hocko <mhocko@xxxxxxxx> wrote:
>
[...]
> I think you really want something like this:
>
> if (flags)
> return -EINVAL;
>
> pid = pidfd_get_pid(fd, &f_flags);
> if (IS_ERR(pid))
> return PTR_ERR(pid);
> task = get_pid_task(pid, PIDTYPE_PID);
> if (!task) {
> ret = -ESRCH;
> goto put_pid;
> }
>
> /*
> * Make sure to chose a thread which still has a reference to mm
> * during the group exit
> */
> p = find_lock_task_mm(task);
> if (!p) {
> ret = -ESRCH;
> goto put_task;
> }
>
> mm = task->mm;
mm = p->mm;
> mmgrab(mm);
> reap = true;
> /* If the work has been done already, just exit with success */
> if (test_bit(MMF_OOM_SKIP, &mm->flags)) {
> reap = false;
> } else if (!task_will_free_mem(p)) {
> reap = false;
> ret = -EINVAL;
> }
> task_unlock(p);
>
> if (!reap)
> goto dropmm;;
>
> /* Do the work*/
>
>
> dropmm:
> mmdrop(mm);
> put_task:
> put_task(task);
> put_pid:
> put_pid(pid);
>
> return ret;
>
> --
> Michal Hocko
> SUSE Labs
