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

src/heap/spaces.cc

Index: src/heap/spaces.cc
diff --git a/src/heap/spaces.cc b/src/heap/spaces.cc
index abf344e79f5316332540c8773b78b3979ffe94db..95d5687a8fa4010fa6523c04d0e34018cc396639 100644
--- a/src/heap/spaces.cc
+++ b/src/heap/spaces.cc
@@ -4,6 +4,8 @@
 
 #include "src/heap/spaces.h"
 
+#include <utility>
+
 #include "src/base/bits.h"
 #include "src/base/platform/platform.h"
 #include "src/base/platform/semaphore.h"
@@ -348,6 +350,7 @@ class MemoryAllocator::Unmapper::UnmapFreeMemoryTask : public v8::Task {
 };
 
 void MemoryAllocator::Unmapper::FreeQueuedChunks() {
+  ReconsiderDelayedChunks();
   if (FLAG_concurrent_sweeping) {
     V8::GetCurrentPlatform()->CallOnBackgroundThread(
         new UnmapFreeMemoryTask(this), v8::Platform::kShortRunningTask);
@@ -381,6 +384,24 @@ void MemoryAllocator::Unmapper::PerformFreeMemoryOnQueuedChunks() {
   }
 }
 
+void MemoryAllocator::Unmapper::ReconsiderDelayedChunks() {
+  std::list<MemoryChunk*> delayed_chunks(std::move(delayed_regular_chunks_));
+  // Move constructed, so the permanent list should be empty.
+  DCHECK(delayed_regular_chunks_.empty());
+  for (auto it = delayed_chunks.begin(); it != delayed_chunks.end(); ++it) {
+    AddMemoryChunkSafe<kRegular>(*it);
+  }
+}
+
+bool MemoryAllocator::CanFreeMemoryChunk(MemoryChunk* chunk) {
+  MarkCompactCollector* mc = isolate_->heap()->mark_compact_collector();
+  // We cannot free memory chunks in new space while the sweeper is running
+  // since a sweeper thread might be stuck right before trying to lock the
+  // corresponding page.
+  return !chunk->InNewSpace() || (mc == nullptr) ||
+         mc->sweeper().IsSweepingCompleted();
+}
+
 bool MemoryAllocator::CommitMemory(Address base, size_t size,
                                    Executability executable) {
   if (!base::VirtualMemory::CommitRegion(base, size,