percpu.c

	schunk = alloc_bootmem(pcpu_chunk_struct_size);
	INIT_LIST_HEAD(&schunk->list);
	schunk->vm = &first_vm;
	schunk->map = smap;
	schunk->map_alloc = ARRAY_SIZE(smap);
	schunk->page = schunk->page_ar;

	if (reserved_size) {
		schunk->free_size = reserved_size;
		pcpu_reserved_chunk = schunk;	/* not for dynamic alloc */
	} else {
		schunk->free_size = dyn_size;
		dyn_size = 0;			/* dynamic area covered */
	}
	schunk->contig_hint = schunk->free_size;

	schunk->map[schunk->map_used++] = -static_size;
	if (schunk->free_size)
		schunk->map[schunk->map_used++] = schunk->free_size;

	pcpu_reserved_chunk_limit = static_size + schunk->free_size;

	/* init dynamic chunk if necessary */
	if (dyn_size) {
		dchunk = alloc_bootmem(sizeof(struct pcpu_chunk));
		INIT_LIST_HEAD(&dchunk->list);
		dchunk->vm = &first_vm;
		dchunk->map = dmap;
		dchunk->map_alloc = ARRAY_SIZE(dmap);
		dchunk->page = schunk->page_ar;	/* share page map with schunk */

		dchunk->contig_hint = dchunk->free_size = dyn_size;
		dchunk->map[dchunk->map_used++] = -pcpu_reserved_chunk_limit;
		dchunk->map[dchunk->map_used++] = dchunk->free_size;
	}

	/* allocate vm address */
	first_vm.flags = VM_ALLOC;
	first_vm.size = pcpu_chunk_size;

	if (!base_addr)
		vm_area_register_early(&first_vm, PAGE_SIZE);
	else {
		/*
		 * Pages already mapped.  No need to remap into
		 * vmalloc area.  In this case the first chunks can't
		 * be mapped or unmapped by percpu and are marked
		 * immutable.
		 */
		first_vm.addr = base_addr;
		schunk->immutable = true;
		if (dchunk)
			dchunk->immutable = true;
	}

	/* assign pages */
	nr_pages = -1;
	for_each_possible_cpu(cpu) {
		for (i = 0; i < pcpu_unit_pages; i++) {
			struct page *page = get_page_fn(cpu, i);

			if (!page)
				break;
			*pcpu_chunk_pagep(schunk, cpu, i) = page;
		}

		BUG_ON(i < PFN_UP(static_size));

		if (nr_pages < 0)
			nr_pages = i;
		else
			BUG_ON(nr_pages != i);
	}

	/* map them */
	if (populate_pte_fn) {
		for_each_possible_cpu(cpu)
			for (i = 0; i < nr_pages; i++)
				populate_pte_fn(pcpu_chunk_addr(schunk,
								cpu, i));

		err = pcpu_map(schunk, 0, nr_pages);
		if (err)
			panic("failed to setup static percpu area, err=%d\n",
			      err);
	}

	/* link the first chunk in */
	if (!dchunk) {
		pcpu_chunk_relocate(schunk, -1);
		pcpu_chunk_addr_insert(schunk);
	} else {
		pcpu_chunk_relocate(dchunk, -1);
		pcpu_chunk_addr_insert(dchunk);
	}

	/* we're done */
	pcpu_base_addr = (void *)pcpu_chunk_addr(schunk, 0, 0);
	return pcpu_unit_size;
}