alloc_pgt_page
mapping_info.alloc_pgt_page = alloc_pgt_page;
top_level_pgt = (unsigned long)alloc_pgt_page(&pgt_data);
pte = (pte_t *)info->alloc_pgt_page(info->context);
void *(*alloc_pgt_page)(void *); /* allocate buf for page table */
.alloc_pgt_page = alloc_pgt_page,
pgd = alloc_pgt_page(NULL);
.alloc_pgt_page = alloc_pgt_page,
image->arch.pgd = alloc_pgt_page(image);
pmd = (pmd_t *)info->alloc_pgt_page(info->context);
pud = (pud_t *)info->alloc_pgt_page(info->context);
p4d = (p4d_t *)info->alloc_pgt_page(info->context);
.alloc_pgt_page = alloc_pgt_page,