diff -r 68c00593de9f -r 17c5d6d4f124 src/mem/ruby/system/System.cc
--- a/src/mem/ruby/system/System.cc	Wed Jul 08 21:06:16 2015 +0100
+++ b/src/mem/ruby/system/System.cc	Wed Jul 08 21:29:59 2015 +0100
@@ -161,7 +161,12 @@
     list<pair<Event*, Tick> > original_events;
     while (!eventq->empty()) {
         Event *curr_head = eventq->getHead();
-        original_events.push_back(make_pair(curr_head, curr_head->when()));
+        if (curr_head->isAutoDelete()) {
+            DPRINTF(RubyCacheTrace, "Event %s auto-deletes when descheduled,"
+                    " not recording\n", curr_head->name());
+        } else {
+            original_events.push_back(make_pair(curr_head, curr_head->when()));
+        }
         eventq->deschedule(curr_head);
     }
 
@@ -191,6 +196,17 @@
     // No longer flushing back to memory.
     m_cooldown_enabled = false;
 
+    // There are several issues with continuing simulation after calling
+    // memWriteback() at the moment, that stem from taking events off the
+    // queue, simulating again, and then putting them back on, whilst
+    // pretending that no time has passed.  One is that some events will have
+    // been deleted, so can't be put back.  Another is that any object
+    // recording the tick something happens may end up storing a tick in the
+    // future.  A simple warning here alerts the user that things may not work
+    // as expected.
+    warn_once("Ruby memory writeback is experimental.  Continuing simulation "
+              "afterwards may not always work as intended.");
+
     // Keep the cache recorder around so that we can dump the trace if a
     // checkpoint is immediately taken.
 }
diff -r 68c00593de9f -r 17c5d6d4f124 src/sim/eventq.hh
--- a/src/sim/eventq.hh	Wed Jul 08 21:06:16 2015 +0100
+++ b/src/sim/eventq.hh	Wed Jul 08 21:29:59 2015 +0100
@@ -338,6 +338,9 @@
     /// See if this is a SimExitEvent (without resorting to RTTI)
     bool isExitEvent() const { return flags.isSet(IsExitEvent); }
 
+    /// Check whether this event will auto-delete
+    bool isAutoDelete() const { return flags.isSet(AutoDelete); }
+
     /// Get the time that the event is scheduled
     Tick when() const { return _when; }