Don't unlink evacuation candidates before sweeping, move them to the end of their list of pages.

src/spaces.cc

Index: src/spaces.cc
diff --git a/src/spaces.cc b/src/spaces.cc
index eeb7ea81d1fb387a87d5a335c78cb01ce6ff1986..adb8dee334df554d223089ce5e830eb6eaae5378 100644
--- a/src/spaces.cc
+++ b/src/spaces.cc
@@ -582,10 +582,6 @@ void MemoryChunk::InsertAfter(MemoryChunk* other) {
 
 
 void MemoryChunk::Unlink() {
-  if (!InNewSpace() && IsFlagSet(SCAN_ON_SCAVENGE)) {
-    heap_->decrement_scan_on_scavenge_pages();
-    ClearFlag(SCAN_ON_SCAVENGE);
-  }
   MemoryChunk* next_element = next_chunk();
   MemoryChunk* prev_element = prev_chunk();
   next_element->set_prev_chunk(prev_element);
@@ -953,7 +949,8 @@ PagedSpace::PagedSpace(Heap* heap,
     : Space(heap, id, executable),
       free_list_(this),
       was_swept_conservatively_(false),
-      unswept_free_bytes_(0) {
+      unswept_free_bytes_(0),
+      end_of_unswept_pages_(NULL) {
   if (id == CODE_SPACE) {
     area_size_ = heap->isolate()->memory_allocator()->
         CodePageAreaSize();
@@ -1126,7 +1123,7 @@ void PagedSpace::IncreaseCapacity(int size) {
 }
 
 
-void PagedSpace::ReleasePage(Page* page, bool unlink) {
+void PagedSpace::ReleasePage(Page* page) {
   ASSERT(page->LiveBytes() == 0);
   ASSERT(AreaSize() == page->area_size());
 
@@ -1138,19 +1135,19 @@ void PagedSpace::ReleasePage(Page* page, bool unlink) {
     DecreaseUnsweptFreeBytes(page);
   }
 
-  // TODO(hpayer): This check is just used for debugging purpose and
-  // should be removed or turned into an assert after investigating the
-  // crash in concurrent sweeping.
-  CHECK(!free_list_.ContainsPageFreeListItems(page));
+  if (page->IsFlagSet(MemoryChunk::SCAN_ON_SCAVENGE)) {
+    heap()->decrement_scan_on_scavenge_pages();
+    page->ClearFlag(MemoryChunk::SCAN_ON_SCAVENGE);
+  }
+
+  ASSERT(!free_list_.ContainsPageFreeListItems(page));
 
   if (Page::FromAllocationTop(allocation_info_.top()) == page) {
     allocation_info_.set_top(NULL);
     allocation_info_.set_limit(NULL);
   }
 
-  if (unlink) {
-    page->Unlink();
-  }
+  page->Unlink();
   if (page->IsFlagSet(MemoryChunk::CONTAINS_ONLY_DATA)) {
     heap()->isolate()->memory_allocator()->Free(page);
   } else {