Reland "[heap] Don't unmap new space pages while sweeping is active"

src/heap/spaces.h

Index: src/heap/spaces.h
diff --git a/src/heap/spaces.h b/src/heap/spaces.h
index ae2f86c32073bd195b377e86e972d997e70767ce..de5ea1b16adc399a977885f4bacffda9c8b22263 100644
--- a/src/heap/spaces.h
+++ b/src/heap/spaces.h
@@ -1205,7 +1205,12 @@ class MemoryAllocator {
     template <ChunkQueueType type>
     void AddMemoryChunkSafe(MemoryChunk* chunk) {
       base::LockGuard<base::Mutex> guard(&mutex_);
-      chunks_[type].push_back(chunk);
+      if (type != kRegular || allocator_->CanFreeMemoryChunk(chunk)) {
+        chunks_[type].push_back(chunk);
+      } else {
+        DCHECK_EQ(type, kRegular);
+        delayed_regular_chunks_.push_back(chunk);
+      }
     }
 
     template <ChunkQueueType type>
@@ -1217,11 +1222,16 @@ class MemoryAllocator {
       return chunk;
     }
 
+    void ReconsiderDelayedChunks();
     void PerformFreeMemoryOnQueuedChunks();
 
     base::Mutex mutex_;
     MemoryAllocator* allocator_;
     std::list<MemoryChunk*> chunks_[kNumberOfChunkQueues];
+    // Delayed chunks cannot be processed in the current unmapping cycle because
+    // of dependencies such as an active sweeper.
+    // See MemoryAllocator::CanFreeMemoryChunk.
+    std::list<MemoryChunk*> delayed_regular_chunks_;
     base::Semaphore pending_unmapping_tasks_semaphore_;
     intptr_t concurrent_unmapping_tasks_active_;
 
@@ -1260,6 +1270,8 @@ class MemoryAllocator {
   template <MemoryAllocator::FreeMode mode = kFull>
   void Free(MemoryChunk* chunk);
 
+  bool CanFreeMemoryChunk(MemoryChunk* chunk);
+
   // Returns allocated spaces in bytes.
   intptr_t Size() { return size_.Value(); }