diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -11321,7 +11321,7 @@
 		m = pmap_kasan_enter_alloc_2m();
 		if (m != NULL) {
 			*pde = (pd_entry_t)(VM_PAGE_TO_PHYS(m) | X86_PG_RW |
-			    X86_PG_PS | X86_PG_V | pg_nx);
+			    X86_PG_PS | X86_PG_V | X86_PG_A | X86_PG_M | pg_nx);
 		} else {
 			m = pmap_kasan_enter_alloc_4k();
 			*pde = (pd_entry_t)(VM_PAGE_TO_PHYS(m) | X86_PG_RW |
@@ -11333,8 +11333,6 @@
 	pte = pmap_pde_to_pte(pde, va);
 	if ((*pte & X86_PG_V) != 0)
 		return;
-	KASSERT((*pte & X86_PG_V) == 0,
-	    ("%s: shadow address %#lx is already mapped", __func__, va));
 	m = pmap_kasan_enter_alloc_4k();
 	*pte = (pt_entry_t)(VM_PAGE_TO_PHYS(m) | X86_PG_RW | X86_PG_V |
 	    X86_PG_M | X86_PG_A | pg_nx);