Index: sys/fs/tmpfs/tmpfs_vnops.c
===================================================================
--- sys/fs/tmpfs/tmpfs_vnops.c	(revisione 237164)
+++ sys/fs/tmpfs/tmpfs_vnops.c	(copia locale)
@@ -510,11 +510,15 @@ tmpfs_mappedread(vm_object_t vobj, vm_object_t tob
 	offset = addr & PAGE_MASK;
 	tlen = MIN(PAGE_SIZE - offset, len);
 
-	if ((vobj == NULL) ||
-	    (vobj->resident_page_count == 0 && vobj->cache == NULL))
+	if (vobj == NULL)
 		goto nocache;
+	
+	VM_OBJECT_LOCK(vobj);
+	if (vobj->resident_page_count == 0 && vm_object_cache_is_empty(vobj)) {
+		VM_OBJECT_UNLOCK(vobj);
+		goto nocache;
+	}
 
-	VM_OBJECT_LOCK(vobj);
 lookupvpg:
 	if (((m = vm_page_lookup(vobj, idx)) != NULL) &&
 	    vm_page_is_valid(m, offset, tlen)) {
@@ -637,14 +641,17 @@ tmpfs_mappedwrite(vm_object_t vobj, vm_object_t to
 	idx = OFF_TO_IDX(addr);
 	offset = addr & PAGE_MASK;
 	tlen = MIN(PAGE_SIZE - offset, len);
+	vpg = NULL;
 
-	if ((vobj == NULL) ||
-	    (vobj->resident_page_count == 0 && vobj->cache == NULL)) {
-		vpg = NULL;
+	if (vobj == NULL)
 		goto nocache;
+
+	VM_OBJECT_LOCK(vobj);
+	if (vobj->resident_page_count == 0 && vm_object_cache_is_empty(vobj)) {
+		VM_OBJECT_UNLOCK(vobj);
+		goto nocache;
 	}
 
-	VM_OBJECT_LOCK(vobj);
 lookupvpg:
 	if (((vpg = vm_page_lookup(vobj, idx)) != NULL) &&
 	    vm_page_is_valid(vpg, offset, tlen)) {
Index: sys/vm/vm_object.c
===================================================================
--- sys/vm/vm_object.c	(revisione 237164)
+++ sys/vm/vm_object.c	(copia locale)
@@ -172,7 +172,7 @@ vm_object_zdtor(void *mem, int size, void *arg)
 	    ("object %p has reservations",
 	    object));
 #endif
-	KASSERT(object->cache == NULL,
+	KASSERT(vm_object_cache_is_empty(object),
 	    ("object %p has cached pages",
 	    object));
 	KASSERT(object->paging_in_progress == 0,
@@ -757,7 +757,7 @@ vm_object_terminate(vm_object_t object)
 	if (__predict_false(!LIST_EMPTY(&object->rvq)))
 		vm_reserv_break_all(object);
 #endif
-	if (__predict_false(object->cache != NULL))
+	if (!vm_object_cache_is_empty(object))
 		vm_page_cache_free(object, 0, 0);
 
 	/*
@@ -1382,7 +1382,7 @@ retry:
 		/*
 		 * Transfer any cached pages from orig_object to new_object.
 		 */
-		if (__predict_false(orig_object->cache != NULL))
+		if (!vm_object_cache_is_empty(orig_object))
 			vm_page_cache_transfer(orig_object, offidxstart,
 			    new_object);
 	}
@@ -1728,7 +1728,7 @@ vm_object_collapse(vm_object_t object)
 				/*
 				 * Free any cached pages from backing_object.
 				 */
-				if (__predict_false(backing_object->cache != NULL))
+				if (!vm_object_cache_is_empty(backing_object))
 					vm_page_cache_free(backing_object, 0, 0);
 			}
 			/*
@@ -1917,7 +1917,7 @@ again:
 	}
 	vm_object_pip_wakeup(object);
 skipmemq:
-	if (__predict_false(object->cache != NULL))
+	if (!vm_object_cache_is_empty(object))
 		vm_page_cache_free(object, start, end);
 }
 
Index: sys/vm/vm_object.h
===================================================================
--- sys/vm/vm_object.h	(revisione 237164)
+++ sys/vm/vm_object.h	(copia locale)
@@ -208,6 +208,16 @@ vm_object_set_flag(vm_object_t object, u_short bit
 	object->flags |= bits;
 }
 
+/*
+ *	The object must be locked or vm_page_queue_free_mtx must be held.
+ */
+static __inline int
+vm_object_cache_is_empty(vm_object_t object)
+{
+
+	return (__predict_true(object->cache == NULL));
+}
+
 void vm_object_clear_flag(vm_object_t object, u_short bits);
 void vm_object_pip_add(vm_object_t object, short i);
 void vm_object_pip_subtract(vm_object_t object, short i);
Index: sys/vm/vm_page.c
===================================================================
--- sys/vm/vm_page.c	(revisione 237164)
+++ sys/vm/vm_page.c	(copia locale)
@@ -1146,7 +1146,7 @@ vm_page_cache_free(vm_object_t object, vm_pindex_t
 	boolean_t empty;
 
 	mtx_lock(&vm_page_queue_free_mtx);
-	if (__predict_false(object->cache == NULL)) {
+	if (vm_object_cache_is_empty(object)) {
 		mtx_unlock(&vm_page_queue_free_mtx);
 		return;
 	}
@@ -1344,7 +1344,7 @@ vm_page_is_cached(vm_object_t object, vm_pindex_t
 	 * exist.
 	 */
 	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
-	if (__predict_true(object->cache == NULL))
+	if (vm_object_cache_is_empty(object))
 		return (FALSE);
 	mtx_lock(&vm_page_queue_free_mtx);
 	m = vm_page_cache_lookup(object, pindex);
Index: sys/vm/vnode_pager.c
===================================================================
--- sys/vm/vnode_pager.c	(revisione 237164)
+++ sys/vm/vnode_pager.c	(copia locale)
@@ -440,7 +440,7 @@ vnode_pager_setsize(vp, nsize)
 			 */
 			vm_page_clear_dirty(m, base, PAGE_SIZE - base);
 		} else if ((nsize & PAGE_MASK) &&
-		    __predict_false(object->cache != NULL)) {
+		    !vm_object_cache_is_empty(object)) {
 			vm_page_cache_free(object, OFF_TO_IDX(nsize),
 			    nobjsize);
 		}
Index: sys/cddl/compat/opensolaris/sys/vnode.h
===================================================================
--- sys/cddl/compat/opensolaris/sys/vnode.h	(revisione 237164)
+++ sys/cddl/compat/opensolaris/sys/vnode.h	(copia locale)
@@ -76,7 +76,7 @@ vn_is_readonly(vnode_t *vp)
 #define	vn_has_cached_data(vp)	\
 	((vp)->v_object != NULL && \
 	 ((vp)->v_object->resident_page_count > 0 || \
-	  (vp)->v_object->cache != NULL))
+	  !vm_object_cache_is_empty((vp)->v_object)))
 #define	vn_exists(vp)		do { } while (0)
 #define	vn_invalid(vp)		do { } while (0)
 #define	vn_renamepath(tdvp, svp, tnm, lentnm)	do { } while (0)