--- a/hotspot/src/share/vm/gc_implementation/g1/g1MMUTracker.cpp	Wed Jun 09 13:53:58 2010 -0400
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1MMUTracker.cpp	Thu Jun 10 08:27:35 2010 -0700
@@ -81,20 +81,24 @@
 
   remove_expired_entries(end);
   if (_no_entries == QueueLength) {
-    // OK, right now when we fill up we bomb out
-    // there are a few ways of dealing with this "gracefully"
+    // OK, we've filled up the queue. There are a few ways
+    // of dealing with this "gracefully"
     //   increase the array size (:-)
     //   remove the oldest entry (this might allow more GC time for
-    //     the time slice than what's allowed)
+    //     the time slice than what's allowed) - this is what we
+    //     currently do
     //   consolidate the two entries with the minimum gap between them
     //     (this might allow less GC time than what's allowed)
-    guarantee(NOT_PRODUCT(ScavengeALot ||) G1UseFixedWindowMMUTracker,
-              "array full, currently we can't recover unless +G1UseFixedWindowMMUTracker");
+
     // In the case where ScavengeALot is true, such overflow is not
     // uncommon; in such cases, we can, without much loss of precision
     // or performance (we are GC'ing most of the time anyway!),
-    // simply overwrite the oldest entry in the tracker: this
-    // is also the behaviour when G1UseFixedWindowMMUTracker is enabled.
+    // simply overwrite the oldest entry in the tracker.
+
+    if (G1PolicyVerbose > 1) {
+      warning("MMU Tracker Queue overflow. Replacing earliest entry.");
+    }
+
     _head_index = trim_index(_head_index + 1);
     assert(_head_index == _tail_index, "Because we have a full circular buffer");
     _tail_index = trim_index(_tail_index + 1);

--- a/hotspot/src/share/vm/gc_implementation/g1/g1_globals.hpp	Wed Jun 09 13:53:58 2010 -0400
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1_globals.hpp	Thu Jun 10 08:27:35 2010 -0700
@@ -254,9 +254,6 @@
           "If non-0 is the size of the G1 survivor space, "                 \
           "otherwise SurvivorRatio is used to determine the size")          \
                                                                             \
-  product(bool, G1UseFixedWindowMMUTracker, false,                          \
-          "If the MMU tracker's memory is full, forget the oldest entry")   \
-                                                                            \
   product(uintx, G1HeapRegionSize, 0,                                       \
           "Size of the G1 regions.")                                        \
                                                                             \

--- a/hotspot/src/share/vm/opto/graphKit.cpp	Wed Jun 09 13:53:58 2010 -0400
+++ b/hotspot/src/share/vm/opto/graphKit.cpp	Thu Jun 10 08:27:35 2010 -0700
@@ -3487,7 +3487,6 @@
 
   Node* tls = __ thread(); // ThreadLocalStorage
 
-  Node* no_ctrl = NULL;
   Node* no_base = __ top();
   float likely  = PROB_LIKELY(0.999);
   float unlikely  = PROB_UNLIKELY(0.999);
@@ -3511,10 +3510,10 @@
   Node* index_adr =  __ AddP(no_base, tls, __ ConX(index_offset));
 
   // Now some values
-
-  Node* index  = __ load(no_ctrl, index_adr, TypeInt::INT, T_INT, Compile::AliasIdxRaw);
-  Node* buffer = __ load(no_ctrl, buffer_adr, TypeRawPtr::NOTNULL, T_ADDRESS, Compile::AliasIdxRaw);
-
+  // Use ctrl to avoid hoisting these values past a safepoint, which could
+  // potentially reset these fields in the JavaThread.
+  Node* index  = __ load(__ ctrl(), index_adr, TypeInt::INT, T_INT, Compile::AliasIdxRaw);
+  Node* buffer = __ load(__ ctrl(), buffer_adr, TypeRawPtr::NOTNULL, T_ADDRESS, Compile::AliasIdxRaw);
 
   // Convert the store obj pointer to an int prior to doing math on it
   // Must use ctrl to prevent "integerized oop" existing across safepoint

--- a/hotspot/test/runtime/6888954/vmerrors.sh	Wed Jun 09 13:53:58 2010 -0400
+++ b/hotspot/test/runtime/6888954/vmerrors.sh	Thu Jun 10 08:27:35 2010 -0700
@@ -65,7 +65,7 @@
     done
     rm -f $$
 
-    i=$(expr $i + 1)
+    i=`expr $i + 1`
 done
 
 exit $rc