Today there is a problem for operating system problem puzzled, the teacher speak level page table for PCB save page table will not change the starting address, through the page table register in order to succeed when addressing positioning level page table must reside memory, but I wondered if can pull up the rest process memory page in the table corresponding to each piece, or the location of the corresponding page table 2 does not change? Or is the operating system will be synchronized block, in what way,