[patch 1/3] smaps: extract pte walker from smaps code

Extracts the page table entry walker from the smaps-specific code in fs/proc/task_mmu.c. This will be used later for clearing the reference bits on pages to measure the number of pages accessed over a time period through /proc/pid/smaps. The new struct pte_walker includes the struct

[patch 1/3] smaps: extract pte walker from smaps code

Extracts the page table entry walker from the smaps-specific code in fs/proc/task_mmu.c. This will be used later for clearing the reference bits on pages to measure the number of pages accessed over a time period through /proc/pid/smaps. The new struct pte_walker includes the struct