关于proc页表的合并 about xv6-k210 HOT 4 CLOSED

int
Proc::proc_pagetable(){
	pagetable = (pagetable_t)kalloc(); // 申请页表
       if(pagetable == 0)
            return 0;
	
	kstack = (uint64)kalloc(); // 申请内核栈
	if(kstack == 0){
		kfree(pagetable);
		return 0;
	}
        memmove(pagetable, kernel_pagetable, PGSIZE); //现在有了映射到内核的页表项
	for(uint i=0; i < PX(2, MAXUVA); ++i){
		pagetable[i] = 0;
	}
	
	trapframe = (Trapframe*)kalloc();  // 申请trapframe页
	if(trapframe == 0){
		kfree(pagetable);
		kfree((void*)kstack);
		return 0;
	}
	return 1;
}