vmalloc

again:
	area = __get_vm_area_node(real_size, align, shift, VM_ALLOC |
				  VM_UNINITIALIZED | vm_flags, start, end, node,
				  gfp_mask, caller);
	if (!area) {
		bool nofail = gfp_mask & __GFP_NOFAIL;
		warn_alloc(gfp_mask, NULL,
			"vmalloc error: size %lu, vm_struct allocation failed%s",
			real_size, (nofail) ? ". Retrying." : "");
		if (nofail) {
			schedule_timeout_uninterruptible(1);
			goto again;
		}
		goto fail;
	}

	/*
	 * Prepare arguments for __vmalloc_area_node() and
	 * kasan_unpoison_vmalloc().
	 */
	if (pgprot_val(prot) == pgprot_val(PAGE_KERNEL)) {
		if (kasan_hw_tags_enabled()) {
			/*
			 * Modify protection bits to allow tagging.
			 * This must be done before mapping.
			 */
			prot = arch_vmap_pgprot_tagged(prot);

			/*
			 * Skip page_alloc poisoning and zeroing for physical
			 * pages backing VM_ALLOC mapping. Memory is instead
			 * poisoned and zeroed by kasan_unpoison_vmalloc().
			 */
			gfp_mask |= __GFP_SKIP_KASAN | __GFP_SKIP_ZERO;
		}

		/* Take note that the mapping is PAGE_KERNEL. */
		kasan_flags |= KASAN_VMALLOC_PROT_NORMAL;
	}

	/* Allocate physical pages and map them into vmalloc space. */
	ret = __vmalloc_area_node(area, gfp_mask, prot, shift, node);
	if (!ret)
		goto fail;

	array_size = (unsigned long)nr_small_pages * sizeof(struct page *);

	if (!(gfp_mask & (GFP_DMA | GFP_DMA32)))
		gfp_mask |= __GFP_HIGHMEM;

	/* Please note that the recursion is strictly bounded. */
	if (array_size > PAGE_SIZE) {
		area->pages = __vmalloc_node(array_size, 1, nested_gfp, node,
					area->caller);
	} else {
		area->pages = kmalloc_node(array_size, nested_gfp, node);
	}

	if (!area->pages) {
		warn_alloc(gfp_mask, NULL,
			"vmalloc error: size %lu, failed to allocated page array size %lu",
			nr_small_pages * PAGE_SIZE, array_size);
		free_vm_area(area);
		return NULL;
	}

	set_vm_area_page_order(area, page_shift - PAGE_SHIFT);
	page_order = vm_area_page_order(area);

	area->nr_pages = vm_area_alloc_pages(gfp_mask | __GFP_NOWARN,
		node, page_order, nr_small_pages, area->pages);

/**
 * vmap - map an array of pages into virtually contiguous space
 * @pages: array of page pointers
 * @count: number of pages to map
 * @flags: vm_area->flags
 * @prot: page protection for the mapping
 *
 * Maps @count pages from @pages into contiguous kernel virtual space.
 * If @flags contains %VM_MAP_PUT_PAGES the ownership of the pages array itself
 * (which must be kmalloc or vmalloc memory) and one reference per pages in it
 * are transferred from the caller to vmap(), and will be freed / dropped when
 * vfree() is called on the return value.
 *
 * Return: the address of the area or %NULL on failure
 */
void *vmap(struct page **pages, unsigned int count,
	   unsigned long flags, pgprot_t prot)
{
	struct vm_struct *area;
	unsigned long addr;
	unsigned long size;		/* In bytes */

	might_sleep();

	if (WARN_ON_ONCE(flags & VM_FLUSH_RESET_PERMS))
		return NULL;

	/*
	 * Your top guard is someone else's bottom guard. Not having a top
	 * guard compromises someone else's mappings too.
	 */
	if (WARN_ON_ONCE(flags & VM_NO_GUARD))
		flags &= ~VM_NO_GUARD;

	if (count > totalram_pages())
		return NULL;

	size = (unsigned long)count << PAGE_SHIFT;
	area = get_vm_area_caller(size, flags, __builtin_return_address(0));
	if (!area)
		return NULL;

	addr = (unsigned long)area->addr;
	if (vmap_pages_range(addr, addr + size, pgprot_nx(prot),
				pages, PAGE_SHIFT) < 0) {
		vunmap(area->addr);
		return NULL;
	}

	if (flags & VM_MAP_PUT_PAGES) {
		area->pages = pages;
		area->nr_pages = count;
	}
	return area->addr;
}

	if (!addr)
		return;

	vm = remove_vm_area(addr);
	if (unlikely(!vm)) {
		WARN(1, KERN_ERR "Trying to vfree() nonexistent vm area (%p)\n",
				addr);
		return;
	}

	if (unlikely(vm->flags & VM_FLUSH_RESET_PERMS))
		vm_reset_perms(vm);
	for (i = 0; i < vm->nr_pages; i++) {
		struct page *page = vm->pages[i];

		BUG_ON(!page);
		mod_memcg_page_state(page, MEMCG_VMALLOC, -1);
		/*
		 * High-order allocs for huge vmallocs are split, so
		 * can be freed as an array of order-0 allocations
		 */
		__free_page(page);
		cond_resched();
	}
	atomic_long_sub(vm->nr_pages, &nr_vmalloc_pages);
	kvfree(vm->pages);
	kfree(vm);
}

void vunmap(const void *addr)
{
	struct vm_struct *vm;

	BUG_ON(in_interrupt());
	might_sleep();

	if (!addr)
		return;
	vm = remove_vm_area(addr);
	if (unlikely(!vm)) {
		WARN(1, KERN_ERR "Trying to vunmap() nonexistent vm area (%p)\n",
				addr);
		return;
	}
	kfree(vm);