In widows there is a mechanism calling "MDL"(Memory descriptor list). When user and kernel trans data,it lock the user space memory firstly,then trans the address to kernel address.After kernel has done the work,it unlock this memory.So the kernel need not to copy the data in user space. Is there a mechanism in linux like this? Which function can lock/unlock the user space's memory? )zYw朆az^jn{zP+rzmj)gX+w?!zXr^-wGg{zŞlzm w(