memory remap question

Hello,I am confused about the index field in page structure,How kernel can get all the virtual page frame in different process according to the unique index??

page table questions

hello ,how to know wheather a pmd maps a 2M physical page or not?? if(pmd_trans_huge(*pmd)){ if(pte_present(*pmd)){ /*page is in ram?*/ } } can I judge it according the above codes?? thanks a lot!!