[heap] Synchronize concurrent chunk map modifications.

src/heap/spaces.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/heap/spaces.h"
 
 #include <utility>
 
 #include "src/base/bits.h"
 #include "src/base/platform/platform.h"
@@ skipping 3014 matching lines @@
 
 // GC support
 Object* LargeObjectSpace::FindObject(Address a) {
   LargePage* page = FindPage(a);
   if (page != NULL) {
     return page->GetObject();
   }
   return Smi::kZero;  // Signaling not found.
 }
 
+LargePage* LargeObjectSpace::FindPageThreadSafe(Address a) {
+  base::LockGuard<base::Mutex> guard(&chunk_map_mutex_);
+  return FindPage(a);
+}
 
 LargePage* LargeObjectSpace::FindPage(Address a) {
   uintptr_t key = reinterpret_cast<uintptr_t>(a) / MemoryChunk::kAlignment;
   base::HashMap::Entry* e = chunk_map_.Lookup(reinterpret_cast<void*>(key),
                                               static_cast<uint32_t>(key));
   if (e != NULL) {
     DCHECK(e->value != NULL);
     LargePage* page = reinterpret_cast<LargePage*>(e->value);
     DCHECK(LargePage::IsValid(page));
     if (page->Contains(a)) {
@@ skipping 16 matching lines @@
     current = current->next_page();
   }
 }
 
 void LargeObjectSpace::InsertChunkMapEntries(LargePage* page) {
   // Register all MemoryChunk::kAlignment-aligned chunks covered by
   // this large page in the chunk map.
   uintptr_t start = reinterpret_cast<uintptr_t>(page) / MemoryChunk::kAlignment;
   uintptr_t limit = (reinterpret_cast<uintptr_t>(page) + (page->size() - 1)) /
                     MemoryChunk::kAlignment;
+  // There may be concurrent access on the chunk map. We have to take the lock
+  // here.
+  base::LockGuard<base::Mutex> guard(&chunk_map_mutex_);
   for (uintptr_t key = start; key <= limit; key++) {
     base::HashMap::Entry* entry = chunk_map_.InsertNew(
         reinterpret_cast<void*>(key), static_cast<uint32_t>(key));
     DCHECK(entry != NULL);
     entry->value = page;
   }
 }
 
 void LargeObjectSpace::RemoveChunkMapEntries(LargePage* page) {
   RemoveChunkMapEntries(page, page->address());
@@ skipping 159 matching lines @@
     object->ShortPrint();
     PrintF("\n");
   }
   printf(" --------------------------------------\n");
   printf(" Marked: %x, LiveCount: %x\n", mark_size, LiveBytes());
 }
 
 #endif  // DEBUG
 }  // namespace internal
 }  // namespace v8