unsigned long get_zeroed_page(int flags);
Returns the virtual address of a free page, initialized to zero
unsigned long __get_free_page(int flags);
Same, but doesn't initialize the contents
unsigned long __get_free_pages(int flags,
unsigned int order);
Returns the starting virtual address of an area of several contiguous pages in physical RAM, with order being log2(<number_of_pages>).Can be computed from the size with the get_order() function.
void free_page(unsigned long addr);
Frees one page.
void free_pages(unsigned long addr,
unsigned int order);
Frees multiple pages. Need to use the same order as in allocation.