Index: sys/amd64/amd64/pmap.c
===================================================================
--- sys/amd64/amd64/pmap.c
+++ sys/amd64/amd64/pmap.c
@@ -1721,6 +1721,7 @@
 				if (cpuid != i)
 					pmap->pm_pcids[i].pm_gen = 0;
 			}
+			atomic_thread_fence_seq_cst();
 		}
 		mask = &pmap->pm_active;
 	}
@@ -1792,6 +1793,7 @@
 				if (cpuid != i)
 					pmap->pm_pcids[i].pm_gen = 0;
 			}
+			atomic_thread_fence_seq_cst();
 		}
 		mask = &pmap->pm_active;
 	}
@@ -1863,6 +1865,7 @@
 				if (cpuid != i)
 					pmap->pm_pcids[i].pm_gen = 0;
 			}
+			atomic_thread_fence_seq_cst();
 		}
 		mask = &pmap->pm_active;
 	}