fget_task
file = fget_task(task, fd);
fd_file = fget_task(task, fd);
extern struct file *fget_task(struct task_struct *task, unsigned int fd);
file = fget_task(task, fd);
filp_epoll = fget_task(task2, slot.efd);
file = fget_task(task, idx);
file = fget_task(task, fd);