Function _kmem_unback

freebsd/vm/vm_kern.c:558–590

* kmem_unback: * * Unmap and free the physical pages underlying the specified virtual * address range. * * A physical page must exist within the specified object at each index * that is being unmapped. */

 *	that is being unmapped.
 */
static struct vmem *
_kmem_unback(vm_object_t object, vm_offset_t addr, vm_size_t size)
{
	struct vmem *arena;
	vm_page_t m, next;
	vm_offset_t end, offset;
	int domain;

	KASSERT(object == kernel_object,
	    ("kmem_unback: only supports kernel object."));

	if (size == 0)
		return (NULL);
	pmap_remove(kernel_pmap, addr, addr + size);
	offset = addr - VM_MIN_KERNEL_ADDRESS;
	end = offset + size;
	VM_OBJECT_WLOCK(object);
	m = vm_page_lookup(object, atop(offset)); 
	domain = vm_page_domain(m);
	if (__predict_true((m->oflags & VPO_KMEM_EXEC) == 0))
		arena = vm_dom[domain].vmd_kernel_arena;
	else
		arena = vm_dom[domain].vmd_kernel_rwx_arena;
	for (; offset < end; offset += PAGE_SIZE, m = next) {
		next = vm_page_next(m);
		vm_page_xbusy_claim(m);
		vm_page_unwire_noq(m);
		vm_page_free(m);
	}
	VM_OBJECT_WUNLOCK(object);

	return (arena);
}

void
kmem_unback(vm_object_t object, vm_offset_t addr, vm_size_t size)