Reland of "[heap] Uncommit pooled pages concurrently"

- Move the concurrent unmapping to MemoryAllocator
- Hide (private) members where possible
- MemoryAllocator:Free is now the bottleneck for freeing
- Pooled pages are either allocated from a set of pooled pages are obtained
  through work stealing from the concurrent unmapper

BUG=chromium:605866, chromium:581412
LOG=N

This reverts commit 25ff296c.

Review-Url: https://codereview.chromium.org/1929503002
Cr-Commit-Position: refs/heads/master@{#35910}

src/deoptimizer.cc

@@ -47,7 +47,7 @@ DeoptimizerData::DeoptimizerData(MemoryAllocator* allocator)
 
 DeoptimizerData::~DeoptimizerData() {
   for (int i = 0; i <= Deoptimizer::kLastBailoutType; ++i) {
-    allocator_->Free(deopt_entry_code_[i]);
+    allocator_->Free<MemoryAllocator::kFull>(deopt_entry_code_[i]);
     deopt_entry_code_[i] = NULL;
   }
 }

src/heap/heap.cc

@@ -157,9 +157,6 @@ Heap::Heap()
       current_gc_flags_(Heap::kNoGCFlags),
       current_gc_callback_flags_(GCCallbackFlags::kNoGCCallbackFlags),
       external_string_table_(this),
-      chunks_queued_for_free_(NULL),
-      concurrent_unmapping_tasks_active_(0),
-      pending_unmapping_tasks_semaphore_(0),
       gc_callbacks_depth_(0),
       deserialization_complete_(false),
       strong_roots_list_(NULL),
@@ -5453,8 +5450,6 @@ void Heap::TearDown() {
   delete scavenge_job_;
   scavenge_job_ = nullptr;
 
-  WaitUntilUnmappingOfFreeChunksCompleted();
-
   delete array_buffer_tracker_;
   array_buffer_tracker_ = nullptr;
 
@@ -6260,75 +6255,6 @@ void Heap::ExternalStringTable::TearDown() {
 }
 
 
-class Heap::UnmapFreeMemoryTask : public v8::Task {
- public:
-  UnmapFreeMemoryTask(Heap* heap, MemoryChunk* head)
-      : heap_(heap), head_(head) {}
-  virtual ~UnmapFreeMemoryTask() {}
-
- private:
-  // v8::Task overrides.
-  void Run() override {
-    heap_->FreeQueuedChunks(head_);
-    heap_->pending_unmapping_tasks_semaphore_.Signal();
-  }
-
-  Heap* heap_;
-  MemoryChunk* head_;
-
-  DISALLOW_COPY_AND_ASSIGN(UnmapFreeMemoryTask);
-};
-
-
-void Heap::WaitUntilUnmappingOfFreeChunksCompleted() {
-  while (concurrent_unmapping_tasks_active_ > 0) {
-    pending_unmapping_tasks_semaphore_.Wait();
-    concurrent_unmapping_tasks_active_--;
-  }
-}
-
-
-void Heap::QueueMemoryChunkForFree(MemoryChunk* chunk) {
-  // PreFree logically frees the memory chunk. However, the actual freeing
-  // will happen on a separate thread sometime later.
-  memory_allocator()->PreFreeMemory(chunk);
-
-  // The chunks added to this queue will be freed by a concurrent thread.
-  chunk->set_next_chunk(chunks_queued_for_free_);
-  chunks_queued_for_free_ = chunk;
-}
-
-
-void Heap::FreeQueuedChunks() {
-  if (chunks_queued_for_free_ != NULL) {
-    if (FLAG_concurrent_sweeping) {
-      V8::GetCurrentPlatform()->CallOnBackgroundThread(
-          new UnmapFreeMemoryTask(this, chunks_queued_for_free_),
-          v8::Platform::kShortRunningTask);
-    } else {
-      FreeQueuedChunks(chunks_queued_for_free_);
-      pending_unmapping_tasks_semaphore_.Signal();
-    }
-    chunks_queued_for_free_ = NULL;
-  } else {
-    // If we do not have anything to unmap, we just signal the semaphore
-    // that we are done.
-    pending_unmapping_tasks_semaphore_.Signal();
-  }
-  concurrent_unmapping_tasks_active_++;
-}
-
-
-void Heap::FreeQueuedChunks(MemoryChunk* list_head) {
-  MemoryChunk* next;
-  MemoryChunk* chunk;
-  for (chunk = list_head; chunk != NULL; chunk = next) {
-    next = chunk->next_chunk();
-    memory_allocator()->PerformFreeMemory(chunk);
-  }
-}
-
-
 void Heap::RememberUnmappedPage(Address page, bool compacted) {
   uintptr_t p = reinterpret_cast<uintptr_t>(page);
   // Tag the page pointer to make it findable in the dump file.

src/heap/heap.h

@@ -780,11 +780,6 @@ class Heap {
 
   inline bool OldGenerationAllocationLimitReached();
 
-  void QueueMemoryChunkForFree(MemoryChunk* chunk);
-  void FreeQueuedChunks(MemoryChunk* list_head);
-  void FreeQueuedChunks();
-  void WaitUntilUnmappingOfFreeChunksCompleted();
-
   // Completely clear the Instanceof cache (to stop it keeping objects alive
   // around a GC).
   inline void CompletelyClearInstanceofCache();
@@ -1397,7 +1392,6 @@ class Heap {
 
  private:
   class PretenuringScope;
-  class UnmapFreeMemoryTask;
 
   // External strings table is a place where all external strings are
   // registered.  We need to keep track of such strings to properly
@@ -2215,12 +2209,6 @@ class Heap {
 
   ExternalStringTable external_string_table_;
 
-  MemoryChunk* chunks_queued_for_free_;
-
-  size_t concurrent_unmapping_tasks_active_;
-
-  base::Semaphore pending_unmapping_tasks_semaphore_;
-
   base::Mutex relocation_mutex_;
 
   int gc_callbacks_depth_;

src/heap/mark-compact.cc

@@ -846,7 +846,7 @@ void MarkCompactCollector::Prepare() {
 
   // If concurrent unmapping tasks are still running, we should wait for
   // them here.
-  heap()->WaitUntilUnmappingOfFreeChunksCompleted();
+  heap()->memory_allocator()->unmapper()->WaitUntilCompleted();
 
   // Clear marking bits if incremental marking is aborted.
   if (was_marked_incrementally_ && heap_->ShouldAbortIncrementalMarking()) {
@@ -3540,7 +3540,7 @@ void MarkCompactCollector::EvacuateNewSpaceAndCandidates() {
   // slots only handles old space (for unboxed doubles), and thus map space can
   // still contain stale pointers. We only free the chunks after pointer updates
   // to still have access to page headers.
-  heap()->FreeQueuedChunks();
+  heap()->memory_allocator()->unmapper()->FreeQueuedChunks();
 
   {
     TRACE_GC(heap()->tracer(), GCTracer::Scope::MC_EVACUATE_CLEAN_UP);
@@ -3728,7 +3728,7 @@ void MarkCompactCollector::ReleaseEvacuationCandidates() {
   }
   evacuation_candidates_.Rewind(0);
   compacting_ = false;
-  heap()->FreeQueuedChunks();
+  heap()->memory_allocator()->unmapper()->FreeQueuedChunks();
 }
 
 int MarkCompactCollector::Sweeper::ParallelSweepSpace(AllocationSpace identity,

src/heap/spaces.cc

@@ -6,11 +6,13 @@
 
 #include "src/base/bits.h"
 #include "src/base/platform/platform.h"
+#include "src/base/platform/semaphore.h"
 #include "src/full-codegen/full-codegen.h"
 #include "src/heap/slot-set.h"
 #include "src/macro-assembler.h"
 #include "src/msan.h"
 #include "src/snapshot/snapshot.h"
+#include "src/v8.h"
 
 namespace v8 {
 namespace internal {
@@ -303,7 +305,8 @@ MemoryAllocator::MemoryAllocator(Isolate* isolate)
       size_(0),
       size_executable_(0),
       lowest_ever_allocated_(reinterpret_cast<void*>(-1)),
-      highest_ever_allocated_(reinterpret_cast<void*>(0)) {}
+      highest_ever_allocated_(reinterpret_cast<void*>(0)),
+      unmapper_(this) {}
 
 bool MemoryAllocator::SetUp(intptr_t capacity, intptr_t capacity_executable,
                             intptr_t code_range_size) {
@@ -322,10 +325,14 @@ bool MemoryAllocator::SetUp(intptr_t capacity, intptr_t capacity_executable,
 
 
 void MemoryAllocator::TearDown() {
-  for (MemoryChunk* chunk : chunk_pool_) {
+  unmapper()->WaitUntilCompleted();
+
+  MemoryChunk* chunk = nullptr;
+  while ((chunk = unmapper()->TryGetPooledMemoryChunkSafe()) != nullptr) {
     FreeMemory(reinterpret_cast<Address>(chunk), MemoryChunk::kPageSize,
                NOT_EXECUTABLE);
   }
+
   // Check that spaces were torn down before MemoryAllocator.
   DCHECK_EQ(size_.Value(), 0);
   // TODO(gc) this will be true again when we fix FreeMemory.
@@ -341,6 +348,55 @@ void MemoryAllocator::TearDown() {
   code_range_ = nullptr;
 }
 
+class MemoryAllocator::Unmapper::UnmapFreeMemoryTask : public v8::Task {
+ public:
+  explicit UnmapFreeMemoryTask(Unmapper* unmapper) : unmapper_(unmapper) {}
+
+ private:
+  // v8::Task overrides.
+  void Run() override {
+    unmapper_->PerformFreeMemoryOnQueuedChunks();
+    unmapper_->pending_unmapping_tasks_semaphore_.Signal();
+  }
+
+  Unmapper* unmapper_;
+  DISALLOW_COPY_AND_ASSIGN(UnmapFreeMemoryTask);
+};
+
+void MemoryAllocator::Unmapper::FreeQueuedChunks() {
+  if (FLAG_concurrent_sweeping) {
+    V8::GetCurrentPlatform()->CallOnBackgroundThread(
+        new UnmapFreeMemoryTask(this), v8::Platform::kShortRunningTask);
+    concurrent_unmapping_tasks_active_++;
+  } else {
+    PerformFreeMemoryOnQueuedChunks();
+  }
+}
+
+bool MemoryAllocator::Unmapper::WaitUntilCompleted() {
+  bool waited = false;
+  while (concurrent_unmapping_tasks_active_ > 0) {
+    pending_unmapping_tasks_semaphore_.Wait();
+    concurrent_unmapping_tasks_active_--;
+    waited = true;
+  }
+  return waited;
+}
+
+void MemoryAllocator::Unmapper::PerformFreeMemoryOnQueuedChunks() {
+  MemoryChunk* chunk = nullptr;
+  // Regular chunks.
+  while ((chunk = GetMemoryChunkSafe<kRegular>()) != nullptr) {
+    bool pooled = chunk->IsFlagSet(MemoryChunk::POOLED);
+    allocator_->PerformFreeMemory(chunk);
+    if (pooled) AddMemoryChunkSafe<kPooled>(chunk);
+  }
+  // Non-regular chunks.
+  while ((chunk = GetMemoryChunkSafe<kNonRegular>()) != nullptr) {
+    allocator_->PerformFreeMemory(chunk);
+  }
+}
+
 bool MemoryAllocator::CommitMemory(Address base, size_t size,
                                    Executability executable) {
   if (!base::VirtualMemory::CommitRegion(base, size,
@@ -740,28 +796,45 @@ void MemoryAllocator::PerformFreeMemory(MemoryChunk* chunk) {
   chunk->ReleaseAllocatedMemory();
 
   base::VirtualMemory* reservation = chunk->reserved_memory();
-  if (reservation->IsReserved()) {
-    FreeMemory(reservation, chunk->executable());
+  if (chunk->IsFlagSet(MemoryChunk::POOLED)) {
+    UncommitBlock(reinterpret_cast<Address>(chunk), MemoryChunk::kPageSize);
   } else {
-    FreeMemory(chunk->address(), chunk->size(), chunk->executable());
+    if (reservation->IsReserved()) {
+      FreeMemory(reservation, chunk->executable());
+    } else {
+      FreeMemory(chunk->address(), chunk->size(), chunk->executable());
+    }
   }
 }
 
-template <MemoryAllocator::AllocationMode mode>
+template <MemoryAllocator::FreeMode mode>
 void MemoryAllocator::Free(MemoryChunk* chunk) {
-  if (mode == kRegular) {
-    PreFreeMemory(chunk);
-    PerformFreeMemory(chunk);
-  } else {
-    DCHECK_EQ(mode, kPooled);
-    FreePooled(chunk);
+  switch (mode) {
+    case kFull:
+      PreFreeMemory(chunk);
+      PerformFreeMemory(chunk);
+      break;
+    case kPooledAndQueue:
+      DCHECK_EQ(chunk->size(), static_cast<size_t>(MemoryChunk::kPageSize));
+      DCHECK_EQ(chunk->executable(), NOT_EXECUTABLE);
+      chunk->SetFlag(MemoryChunk::POOLED);
+    // Fall through to kPreFreeAndQueue.
+    case kPreFreeAndQueue:
+      PreFreeMemory(chunk);
+      // The chunks added to this queue will be freed by a concurrent thread.
+      unmapper()->AddMemoryChunkSafe(chunk);
+      break;
+    default:
+      UNREACHABLE();
   }
 }
 
-template void MemoryAllocator::Free<MemoryAllocator::kRegular>(
+template void MemoryAllocator::Free<MemoryAllocator::kFull>(MemoryChunk* chunk);
+
+template void MemoryAllocator::Free<MemoryAllocator::kPreFreeAndQueue>(
     MemoryChunk* chunk);
 
-template void MemoryAllocator::Free<MemoryAllocator::kPooled>(
+template void MemoryAllocator::Free<MemoryAllocator::kPooledAndQueue>(
     MemoryChunk* chunk);
 
 template <MemoryAllocator::AllocationMode alloc_mode, typename SpaceType>
@@ -800,9 +873,9 @@ LargePage* MemoryAllocator::AllocateLargePage(intptr_t size,
 
 template <typename SpaceType>
 MemoryChunk* MemoryAllocator::AllocatePagePooled(SpaceType* owner) {
-  if (chunk_pool_.is_empty()) return nullptr;
+  MemoryChunk* chunk = unmapper()->TryGetPooledMemoryChunkSafe();
+  if (chunk == nullptr) return nullptr;
   const int size = MemoryChunk::kPageSize;
-  MemoryChunk* chunk = chunk_pool_.RemoveLast();
   const Address start = reinterpret_cast<Address>(chunk);
   const Address area_start = start + MemoryChunk::kObjectStartOffset;
   const Address area_end = start + size;
@@ -814,18 +887,6 @@ MemoryChunk* MemoryAllocator::AllocatePagePooled(SpaceType* owner) {
   return chunk;
 }
 
-void MemoryAllocator::FreePooled(MemoryChunk* chunk) {
-  DCHECK_EQ(chunk->size(), static_cast<size_t>(MemoryChunk::kPageSize));
-  DCHECK_EQ(chunk->executable(), NOT_EXECUTABLE);
-  chunk_pool_.Add(chunk);
-  intptr_t chunk_size = static_cast<intptr_t>(chunk->size());
-  if (chunk->executable() == EXECUTABLE) {
-    size_executable_.Increment(-chunk_size);
-  }
-  size_.Increment(-chunk_size);
-  UncommitBlock(reinterpret_cast<Address>(chunk), MemoryChunk::kPageSize);
-}
-
 bool MemoryAllocator::CommitBlock(Address start, size_t size,
                                   Executability executable) {
   if (!CommitMemory(start, size, executable)) return false;
@@ -968,12 +1029,16 @@ bool MemoryAllocator::CommitExecutableMemory(base::VirtualMemory* vm,
 // MemoryChunk implementation
 
 void MemoryChunk::ReleaseAllocatedMemory() {
-  delete skip_list_;
-  skip_list_ = nullptr;
-  delete mutex_;
-  mutex_ = nullptr;
-  ReleaseOldToNewSlots();
-  ReleaseOldToOldSlots();
+  if (skip_list_ != nullptr) {
+    delete skip_list_;
+    skip_list_ = nullptr;
+  }
+  if (mutex_ != nullptr) {
+    delete mutex_;
+    mutex_ = nullptr;
+  }
+  if (old_to_new_slots_ != nullptr) ReleaseOldToNewSlots();
+  if (old_to_old_slots_ != nullptr) ReleaseOldToOldSlots();
 }
 
 static SlotSet* AllocateSlotSet(size_t size, Address page_start) {
@@ -1055,7 +1120,7 @@ bool PagedSpace::HasBeenSetUp() { return true; }
 void PagedSpace::TearDown() {
   PageIterator iterator(this);
   while (iterator.has_next()) {
-    heap()->memory_allocator()->Free(iterator.next());
+    heap()->memory_allocator()->Free<MemoryAllocator::kFull>(iterator.next());
   }
   anchor_.set_next_page(&anchor_);
   anchor_.set_prev_page(&anchor_);
@@ -1245,7 +1310,7 @@ void PagedSpace::ReleasePage(Page* page) {
   }
 
   AccountUncommitted(static_cast<intptr_t>(page->size()));
-  heap()->QueueMemoryChunkForFree(page);
+  heap()->memory_allocator()->Free<MemoryAllocator::kPreFreeAndQueue>(page);
 
   DCHECK(Capacity() > 0);
   accounting_stats_.ShrinkSpace(AreaSize());
@@ -1706,12 +1771,14 @@ bool SemiSpace::Uncommit() {
   DCHECK(is_committed());
   NewSpacePageIterator it(this);
   while (it.has_next()) {
-    heap()->memory_allocator()->Free<MemoryAllocator::kPooled>(it.next());
+    heap()->memory_allocator()->Free<MemoryAllocator::kPooledAndQueue>(
+        it.next());
   }
   anchor()->set_next_page(anchor());
   anchor()->set_prev_page(anchor());
   AccountUncommitted(current_capacity_);
   committed_ = false;
+  heap()->memory_allocator()->unmapper()->FreeQueuedChunks();
   return true;
 }
 
@@ -1786,10 +1853,12 @@ bool SemiSpace::ShrinkTo(int new_capacity) {
       new_last_page = last_page->prev_page();
       new_last_page->set_next_page(anchor());
       anchor()->set_prev_page(new_last_page);
-      heap()->memory_allocator()->Free<MemoryAllocator::kPooled>(last_page);
+      heap()->memory_allocator()->Free<MemoryAllocator::kPooledAndQueue>(
+          last_page);
       delta_pages--;
     }
     AccountUncommitted(static_cast<intptr_t>(delta));
+    heap()->memory_allocator()->unmapper()->FreeQueuedChunks();
   }
   current_capacity_ = new_capacity;
   return true;
@@ -2884,7 +2953,7 @@ void LargeObjectSpace::TearDown() {
     ObjectSpace space = static_cast<ObjectSpace>(1 << identity());
     heap()->memory_allocator()->PerformAllocationCallback(
         space, kAllocationActionFree, page->size());
-    heap()->memory_allocator()->Free(page);
+    heap()->memory_allocator()->Free<MemoryAllocator::kFull>(page);
   }
   SetUp();
 }
@@ -3027,7 +3096,7 @@ void LargeObjectSpace::FreeUnmarkedObjects() {
                           static_cast<uint32_t>(key));
       }
 
-      heap()->QueueMemoryChunkForFree(page);
+      heap()->memory_allocator()->Free<MemoryAllocator::kPreFreeAndQueue>(page);
     }
   }
 }

src/heap/spaces.h

@@ -5,6 +5,8 @@
 #ifndef V8_HEAP_SPACES_H_
 #define V8_HEAP_SPACES_H_
 
+#include <list>
+
 #include "src/allocation.h"
 #include "src/atomic-utils.h"
 #include "src/base/atomicops.h"
@@ -440,6 +442,10 @@ class MemoryChunk {
     // still has to be performed.
     PRE_FREED,
 
+    // |POOLED|: When actually freeing this chunk, only uncommit and do not
+    // give up the reservation as we still reuse the chunk at some point.
+    POOLED,
+
     // |COMPACTION_WAS_ABORTED|: Indicates that the compaction in this page
     //   has been aborted and needs special handling by the sweeper.
     COMPACTION_WAS_ABORTED,
@@ -1261,15 +1267,92 @@ class SkipList {
 // A space acquires chunks of memory from the operating system. The memory
 // allocator allocated and deallocates pages for the paged heap spaces and large
 // pages for large object space.
-//
-// Each space has to manage it's own pages.
-//
 class MemoryAllocator {
  public:
+  // Unmapper takes care of concurrently unmapping and uncommitting memory
+  // chunks.
+  class Unmapper {
+   public:
+    class UnmapFreeMemoryTask;
+
+    explicit Unmapper(MemoryAllocator* allocator)
+        : allocator_(allocator),
+          pending_unmapping_tasks_semaphore_(0),
+          concurrent_unmapping_tasks_active_(0) {}
+
+    void AddMemoryChunkSafe(MemoryChunk* chunk) {
+      if ((chunk->size() == Page::kPageSize) &&
+          (chunk->executable() != EXECUTABLE)) {
+        AddMemoryChunkSafe<kRegular>(chunk);
+      } else {
+        AddMemoryChunkSafe<kNonRegular>(chunk);
+      }
+    }
+
+    MemoryChunk* TryGetPooledMemoryChunkSafe() {
+      // Procedure:
+      // (1) Try to get a chunk that was declared as pooled and already has
+      // been uncommitted.
+      // (2) Try to steal any memory chunk of kPageSize that would've been
+      // unmapped.
+      MemoryChunk* chunk = GetMemoryChunkSafe<kPooled>();
+      if (chunk == nullptr) {
+        chunk = GetMemoryChunkSafe<kRegular>();
+        if (chunk != nullptr) {
+          // For stolen chunks we need to manually free any allocated memory.
+          chunk->ReleaseAllocatedMemory();
+        }
+      }
+      return chunk;
+    }
+
+    void FreeQueuedChunks();
+    bool WaitUntilCompleted();
+
+   private:
+    enum ChunkQueueType {
+      kRegular,     // Pages of kPageSize that do not live in a CodeRange and
+                    // can thus be used for stealing.
+      kNonRegular,  // Large chunks and executable chunks.
+      kPooled,      // Pooled chunks, already uncommited and ready for reuse.
+      kNumberOfChunkQueues,
+    };
+
+    template <ChunkQueueType type>
+    void AddMemoryChunkSafe(MemoryChunk* chunk) {
+      base::LockGuard<base::Mutex> guard(&mutex_);
+      chunks_[type].push_back(chunk);
+    }
+
+    template <ChunkQueueType type>
+    MemoryChunk* GetMemoryChunkSafe() {
+      base::LockGuard<base::Mutex> guard(&mutex_);
+      if (chunks_[type].empty()) return nullptr;
+      MemoryChunk* chunk = chunks_[type].front();
+      chunks_[type].pop_front();
+      return chunk;
+    }
+
+    void PerformFreeMemoryOnQueuedChunks();
+
+    base::Mutex mutex_;
+    MemoryAllocator* allocator_;
+    std::list<MemoryChunk*> chunks_[kNumberOfChunkQueues];
+    base::Semaphore pending_unmapping_tasks_semaphore_;
+    intptr_t concurrent_unmapping_tasks_active_;
+
+    friend class MemoryAllocator;
+  };
+
   enum AllocationMode {
     kRegular,
     kPooled,
   };
+  enum FreeMode {
+    kFull,
+    kPreFreeAndQueue,
+    kPooledAndQueue,
+  };
 
   explicit MemoryAllocator(Isolate* isolate);
 
@@ -1290,16 +1373,7 @@ class MemoryAllocator {
   LargePage* AllocateLargePage(intptr_t size, LargeObjectSpace* owner,
                                Executability executable);
 
-  // PreFree logically frees the object, i.e., it takes care of the size
-  // bookkeeping and calls the allocation callback.
-  void PreFreeMemory(MemoryChunk* chunk);
-
-  // FreeMemory can be called concurrently when PreFree was executed before.
-  void PerformFreeMemory(MemoryChunk* chunk);
-
-  // Free is a wrapper method. For kRegular AllocationMode it  calls PreFree and
-  // PerformFreeMemory together. For kPooled it will dispatch to pooled free.
-  template <MemoryAllocator::AllocationMode mode = kRegular>
+  template <MemoryAllocator::FreeMode mode = kFull>
   void Free(MemoryChunk* chunk);
 
   // Returns allocated spaces in bytes.
@@ -1405,16 +1479,21 @@ class MemoryAllocator {
                                               size_t reserved_size);
 
   CodeRange* code_range() { return code_range_; }
+  Unmapper* unmapper() { return &unmapper_; }
 
  private:
+  // PreFree logically frees the object, i.e., it takes care of the size
+  // bookkeeping and calls the allocation callback.
+  void PreFreeMemory(MemoryChunk* chunk);
+
+  // FreeMemory can be called concurrently when PreFree was executed before.
+  void PerformFreeMemory(MemoryChunk* chunk);
+
   // See AllocatePage for public interface. Note that currently we only support
   // pools for NOT_EXECUTABLE pages of size MemoryChunk::kPageSize.
   template <typename SpaceType>
   MemoryChunk* AllocatePagePooled(SpaceType* owner);
 
-  // Free that chunk into the pool.
-  void FreePooled(MemoryChunk* chunk);
-
   Isolate* isolate_;
 
   CodeRange* code_range_;
@@ -1470,9 +1549,8 @@ class MemoryAllocator {
     } while ((high > ptr) && !highest_ever_allocated_.TrySetValue(ptr, high));
   }
 
-  List<MemoryChunk*> chunk_pool_;
-
   base::VirtualMemory last_chunk_;
+  Unmapper unmapper_;
 
   friend class TestCodeRangeScope;
 

test/cctest/heap/test-spaces.cc

@@ -193,7 +193,7 @@ static void VerifyMemoryChunk(Isolate* isolate,
     CHECK(static_cast<size_t>(memory_chunk->area_size()) ==
           second_commit_area_size);
 
-    memory_allocator->Free(memory_chunk);
+    memory_allocator->Free<MemoryAllocator::kFull>(memory_chunk);
   }
   memory_allocator->TearDown();
   delete memory_allocator;