--- a/hotspot/src/share/vm/gc/g1/g1Allocator.cpp	Tue Aug 25 21:05:26 2015 +0200
+++ b/hotspot/src/share/vm/gc/g1/g1Allocator.cpp	Tue Aug 25 17:22:56 2015 -0400
@@ -367,7 +367,7 @@
   _max = _bottom + HeapRegion::min_region_size_in_words();
 
   // Tell mark-sweep that objects in this region are not to be marked.
-  G1MarkSweep::mark_range_archive(MemRegion(_bottom, HeapRegion::GrainWords));
+  G1MarkSweep::set_range_archive(MemRegion(_bottom, HeapRegion::GrainWords), true);
 
   // Since we've modified the old set, call update_sizes.
   _g1h->g1mm()->update_sizes();

--- a/hotspot/src/share/vm/gc/g1/g1CollectedHeap.cpp	Tue Aug 25 21:05:26 2015 +0200
+++ b/hotspot/src/share/vm/gc/g1/g1CollectedHeap.cpp	Tue Aug 25 17:22:56 2015 -0400
@@ -65,6 +65,7 @@
 #include "memory/iterator.hpp"
 #include "oops/oop.inline.hpp"
 #include "runtime/atomic.inline.hpp"
+#include "runtime/init.hpp"
 #include "runtime/orderAccess.inline.hpp"
 #include "runtime/vmThread.hpp"
 #include "utilities/globalDefinitions.hpp"
@@ -949,6 +950,7 @@
 }
 
 bool G1CollectedHeap::alloc_archive_regions(MemRegion* ranges, size_t count) {
+  assert(!is_init_completed(), "Expect to be called at JVM init time");
   assert(ranges != NULL, "MemRegion array NULL");
   assert(count != 0, "No MemRegions provided");
   MutexLockerEx x(Heap_lock);
@@ -1037,12 +1039,13 @@
     }
 
     // Notify mark-sweep of the archive range.
-    G1MarkSweep::mark_range_archive(curr_range);
+    G1MarkSweep::set_range_archive(curr_range, true);
   }
   return true;
 }
 
 void G1CollectedHeap::fill_archive_regions(MemRegion* ranges, size_t count) {
+  assert(!is_init_completed(), "Expect to be called at JVM init time");
   assert(ranges != NULL, "MemRegion array NULL");
   assert(count != 0, "No MemRegions provided");
   MemRegion reserved = _hrm.reserved();
@@ -1125,6 +1128,81 @@
   return result;
 }
 
+void G1CollectedHeap::dealloc_archive_regions(MemRegion* ranges, size_t count) {
+  assert(!is_init_completed(), "Expect to be called at JVM init time");
+  assert(ranges != NULL, "MemRegion array NULL");
+  assert(count != 0, "No MemRegions provided");
+  MemRegion reserved = _hrm.reserved();
+  HeapWord* prev_last_addr = NULL;
+  HeapRegion* prev_last_region = NULL;
+  size_t size_used = 0;
+  size_t uncommitted_regions = 0;
+
+  // For each Memregion, free the G1 regions that constitute it, and
+  // notify mark-sweep that the range is no longer to be considered 'archive.'
+  MutexLockerEx x(Heap_lock);
+  for (size_t i = 0; i < count; i++) {
+    HeapWord* start_address = ranges[i].start();
+    HeapWord* last_address = ranges[i].last();
+
+    assert(reserved.contains(start_address) && reserved.contains(last_address),
+           err_msg("MemRegion outside of heap [" PTR_FORMAT ", " PTR_FORMAT "]",
+                   p2i(start_address), p2i(last_address)));
+    assert(start_address > prev_last_addr,
+           err_msg("Ranges not in ascending order: " PTR_FORMAT " <= " PTR_FORMAT ,
+                   p2i(start_address), p2i(prev_last_addr)));
+    size_used += ranges[i].byte_size();
+    prev_last_addr = last_address;
+
+    HeapRegion* start_region = _hrm.addr_to_region(start_address);
+    HeapRegion* last_region = _hrm.addr_to_region(last_address);
+
+    // Check for ranges that start in the same G1 region in which the previous
+    // range ended, and adjust the start address so we don't try to free
+    // the same region again. If the current range is entirely within that
+    // region, skip it.
+    if (start_region == prev_last_region) {
+      start_address = start_region->end();
+      if (start_address > last_address) {
+        continue;
+      }
+      start_region = _hrm.addr_to_region(start_address);
+    }
+    prev_last_region = last_region;
+
+    // After verifying that each region was marked as an archive region by
+    // alloc_archive_regions, set it free and empty and uncommit it.
+    HeapRegion* curr_region = start_region;
+    while (curr_region != NULL) {
+      guarantee(curr_region->is_archive(),
+                err_msg("Expected archive region at index %u", curr_region->hrm_index()));
+      uint curr_index = curr_region->hrm_index();
+      _old_set.remove(curr_region);
+      curr_region->set_free();
+      curr_region->set_top(curr_region->bottom());
+      if (curr_region != last_region) {
+        curr_region = _hrm.next_region_in_heap(curr_region);
+      } else {
+        curr_region = NULL;
+      }
+      _hrm.shrink_at(curr_index, 1);
+      uncommitted_regions++;
+    }
+
+    // Notify mark-sweep that this is no longer an archive range.
+    G1MarkSweep::set_range_archive(ranges[i], false);
+  }
+
+  if (uncommitted_regions != 0) {
+    ergo_verbose1(ErgoHeapSizing,
+                  "attempt heap shrinking",
+                  ergo_format_reason("uncommitted archive regions")
+                  ergo_format_byte("total size"),
+                  HeapRegion::GrainWords * HeapWordSize * uncommitted_regions);
+  }
+  decrease_used(size_used);
+}
+
 HeapWord* G1CollectedHeap::attempt_allocation_humongous(size_t word_size,
                                                         uint* gc_count_before_ret,
                                                         uint* gclocker_retry_count_ret) {

--- a/hotspot/src/share/vm/gc/g1/g1CollectedHeap.hpp	Tue Aug 25 21:05:26 2015 +0200
+++ b/hotspot/src/share/vm/gc/g1/g1CollectedHeap.hpp	Tue Aug 25 17:22:56 2015 -0400
@@ -757,6 +757,12 @@
   // alloc_archive_regions, and after class loading has occurred.
   void fill_archive_regions(MemRegion* range, size_t count);
 
+  // For each of the specified MemRegions, uncommit the containing G1 regions
+  // which had been allocated by alloc_archive_regions. This should be called
+  // rather than fill_archive_regions at JVM init time if the archive file
+  // mapping failed, with the same non-overlapping and sorted MemRegion array.
+  void dealloc_archive_regions(MemRegion* range, size_t count);
+
 protected:
 
   // Shrink the garbage-first heap by at most the given size (in bytes!).

--- a/hotspot/src/share/vm/gc/g1/g1MarkSweep.cpp	Tue Aug 25 21:05:26 2015 +0200
+++ b/hotspot/src/share/vm/gc/g1/g1MarkSweep.cpp	Tue Aug 25 17:22:56 2015 -0400
@@ -310,9 +310,9 @@
                                  HeapRegion::GrainBytes);
 }
 
-void G1MarkSweep::mark_range_archive(MemRegion range) {
+void G1MarkSweep::set_range_archive(MemRegion range, bool is_archive) {
   assert(_archive_check_enabled, "archive range check not enabled");
-  _archive_region_map.set_by_address(range, true);
+  _archive_region_map.set_by_address(range, is_archive);
 }
 
 bool G1MarkSweep::in_archive_range(oop object) {

--- a/hotspot/src/share/vm/gc/g1/g1MarkSweep.hpp	Tue Aug 25 21:05:26 2015 +0200
+++ b/hotspot/src/share/vm/gc/g1/g1MarkSweep.hpp	Tue Aug 25 17:22:56 2015 -0400
@@ -58,8 +58,8 @@
   // Create the _archive_region_map which is used to identify archive objects.
   static void enable_archive_object_check();
 
-  // Mark the regions containing the specified address range as archive regions.
-  static void mark_range_archive(MemRegion range);
+  // Set the regions containing the specified address range as archive/non-archive.
+  static void set_range_archive(MemRegion range, bool is_archive);
 
   // Check if an object is in an archive region using the _archive_region_map.
   static bool in_archive_range(oop object);

--- a/hotspot/src/share/vm/gc/g1/heapRegionManager.cpp	Tue Aug 25 21:05:26 2015 +0200
+++ b/hotspot/src/share/vm/gc/g1/heapRegionManager.cpp	Tue Aug 25 17:22:56 2015 -0400
@@ -426,7 +426,7 @@
       (num_last_found = find_empty_from_idx_reverse(cur, &idx_last_found)) > 0) {
     uint to_remove = MIN2(num_regions_to_remove - removed, num_last_found);
 
-    uncommit_regions(idx_last_found + num_last_found - to_remove, to_remove);
+    shrink_at(idx_last_found + num_last_found - to_remove, to_remove);
 
     cur = idx_last_found;
     removed += to_remove;
@@ -437,6 +437,17 @@
   return removed;
 }
 
+void HeapRegionManager::shrink_at(uint index, size_t num_regions) {
+#ifdef ASSERT
+  for (uint i = index; i < (index + num_regions); i++) {
+    assert(is_available(i), err_msg("Expected available region at index %u", i));
+    assert(at(i)->is_empty(), err_msg("Expected empty region at index %u", i));
+    assert(at(i)->is_free(), err_msg("Expected free region at index %u", i));
+  }
+#endif
+  uncommit_regions(index, num_regions);
+}
+
 uint HeapRegionManager::find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const {
   guarantee(start_idx < _allocated_heapregions_length, "checking");
   guarantee(res_idx != NULL, "checking");

--- a/hotspot/src/share/vm/gc/g1/heapRegionManager.hpp	Tue Aug 25 21:05:26 2015 +0200
+++ b/hotspot/src/share/vm/gc/g1/heapRegionManager.hpp	Tue Aug 25 17:22:56 2015 -0400
@@ -241,6 +241,10 @@
   // Return the actual number of uncommitted regions.
   uint shrink_by(uint num_regions_to_remove);
 
+  // Uncommit a number of regions starting at the specified index, which must be available,
+  // empty, and free.
+  void shrink_at(uint index, size_t num_regions);
+
   void verify();
 
   // Do some sanity checking.

--- a/hotspot/src/share/vm/memory/filemap.cpp	Tue Aug 25 21:05:26 2015 +0200
+++ b/hotspot/src/share/vm/memory/filemap.cpp	Tue Aug 25 17:22:56 2015 -0400
@@ -707,12 +707,16 @@
                                     addr, string_ranges[i].byte_size(), si->_read_only,
                                     si->_allow_exec);
         if (base == NULL || base != addr) {
+          // dealloc the string regions from java heap
+          dealloc_string_regions();
           fail_continue("Unable to map shared string space at required address.");
           return false;
         }
       }
 
       if (!verify_string_regions()) {
+        // dealloc the string regions from java heap
+        dealloc_string_regions();
         fail_continue("Shared string regions are corrupt");
         return false;
       }
@@ -745,12 +749,14 @@
 }
 
 void FileMapInfo::fixup_string_regions() {
+#if INCLUDE_ALL_GCS
   // If any string regions were found, call the fill routine to make them parseable.
   // Note that string_ranges may be non-NULL even if no ranges were found.
   if (num_ranges != 0) {
     assert(string_ranges != NULL, "Null string_ranges array with non-zero count");
     G1CollectedHeap::heap()->fill_archive_regions(string_ranges, num_ranges);
   }
+#endif
 }
 
 bool FileMapInfo::verify_region_checksum(int i) {
@@ -793,20 +799,14 @@
   }
 }
 
-void FileMapInfo::unmap_string_regions() {
-  for (int i = MetaspaceShared::first_string;
-           i < MetaspaceShared::first_string + MetaspaceShared::max_strings; i++) {
-    struct FileMapInfo::FileMapHeader::space_info* si = &_header->_space[i];
-    size_t used = si->_used;
-    if (used > 0) {
-      size_t size = align_size_up(used, os::vm_allocation_granularity());
-      char* addr = (char*)((void*)oopDesc::decode_heap_oop_not_null(
-                                             (narrowOop)si->_addr._offset));
-      if (!os::unmap_memory(addr, size)) {
-        fail_stop("Unable to unmap shared space.");
-      }
-    }
+// dealloc the archived string region from java heap
+void FileMapInfo::dealloc_string_regions() {
+#if INCLUDE_ALL_GCS
+  if (num_ranges > 0) {
+    assert(string_ranges != NULL, "Null string_ranges array with non-zero count");
+    G1CollectedHeap::heap()->dealloc_archive_regions(string_ranges, num_ranges);
   }
+#endif
 }
 
 void FileMapInfo::assert_mark(bool check) {
@@ -967,7 +967,9 @@
         map_info->_header->_space[i]._addr._base = NULL;
       }
     }
-    map_info->unmap_string_regions();
+    // Dealloc the string regions only without unmapping. The string regions are part
+    // of the java heap. Unmapping of the heap regions are managed by GC.
+    map_info->dealloc_string_regions();
   } else if (DumpSharedSpaces) {
     fail_stop("%s", msg);
   }

--- a/hotspot/src/share/vm/memory/filemap.hpp	Tue Aug 25 21:05:26 2015 +0200
+++ b/hotspot/src/share/vm/memory/filemap.hpp	Tue Aug 25 17:22:56 2015 -0400
@@ -208,7 +208,7 @@
   bool  verify_string_regions();
   void  fixup_string_regions();
   void  unmap_region(int i);
-  void  unmap_string_regions();
+  void  dealloc_string_regions();
   bool  verify_region_checksum(int i);
   void  close();
   bool  is_open() { return _file_open; }

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/test/runtime/SharedArchiveFile/SharedStringsRunAuto.java	Tue Aug 25 17:22:56 2015 -0400
@@ -0,0 +1,67 @@
+/*
+ * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test SharedStringsAuto
+ * @summary Test -Xshare:auto with shared strings.
+ * Feature support: G1GC only, compressed oops/kptrs, 64-bit os, not on windows
+ * @requires (sun.arch.data.model != "32") & (os.family != "windows")
+ * @requires (vm.opt.UseCompressedOops == null) | (vm.opt.UseCompressedOops == true)
+ * @requires (vm.gc=="G1" | vm.gc=="null")
+ * @library /testlibrary
+ * @modules java.base/sun.misc
+ *          java.management
+ * @run main SharedStringsRunAuto
+ */
+
+import jdk.test.lib.*;
+import java.io.File;
+
+public class SharedStringsRunAuto {
+    public static void main(String[] args) throws Exception {
+        // Dump
+        ProcessBuilder pb = ProcessTools.createJavaProcessBuilder(
+            "-XX:+UnlockDiagnosticVMOptions",
+            "-XX:SharedArchiveFile=./SharedStringsRunAuto.jsa",
+            "-XX:+UseCompressedOops", "-XX:+UseG1GC",
+            "-XX:+PrintSharedSpaces",
+            "-Xshare:dump");
+
+        new OutputAnalyzer(pb.start())
+            .shouldContain("Loading classes to share")
+            .shouldContain("Shared string table stats")
+            .shouldHaveExitValue(0);
+
+        // Run with -Xshare:auto
+        pb = ProcessTools.createJavaProcessBuilder(
+           "-XX:+UnlockDiagnosticVMOptions",
+           "-XX:SharedArchiveFile=./SharedStringsRunAuto.jsa",
+           "-XX:+UseCompressedOops", "-XX:+UseG1GC",
+           "-Xshare:auto",
+           "-version");
+
+        new OutputAnalyzer(pb.start())
+            .shouldMatch("(java|openjdk) version")
+            .shouldHaveExitValue(0);
+    }
+}