Index: head/sys/vm/vm_phys.c
===================================================================
--- head/sys/vm/vm_phys.c
+++ head/sys/vm/vm_phys.c
@@ -1189,6 +1189,8 @@
 					 */
 					pa = VM_PAGE_TO_PHYS(m_ret);
 					pa_end = pa + size;
+					if (pa_end < pa)
+						continue;
 					for (;;) {
 						pa += 1 << (PAGE_SHIFT +
 						    VM_NFREEORDER - 1);