free_pgt_page
void (*free_pgt_page)(void *, void *); /* free buf for page table */
.free_pgt_page = free_pgt_page,
info->free_pgt_page(pte, info->context);
info->free_pgt_page(pmd, info->context);
info->free_pgt_page(pud, info->context);
info->free_pgt_page(p4d, info->context);
info->free_pgt_page(pgd, info->context);