[heap] Ensure that the sweeper does not lose unswept pages.

src/heap/mark-compact.cc

 // Copyright 2012 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/mark-compact.h"
 
 #include "src/base/atomicops.h"
 #include "src/base/bits.h"
 #include "src/base/sys-info.h"
 #include "src/code-stubs.h"
@@ skipping 3723 matching lines @@
     if ((required_freed_bytes) > 0 && (max_freed >= required_freed_bytes))
       return max_freed;
     if ((max_pages > 0) && (pages_freed >= max_pages)) return max_freed;
   }
   return max_freed;
 }
 
 int MarkCompactCollector::Sweeper::ParallelSweepPage(Page* page,
                                                      AllocationSpace identity) {
   int max_freed = 0;
-  if (page->mutex()->TryLock()) {
+  {
+    base::LockGuard<base::Mutex> guard(page->mutex());
     // If this page was already swept in the meantime, we can return here.
-    if (page->concurrent_sweeping_state().Value() != Page::kSweepingPending) {
-      page->mutex()->Unlock();
-      return 0;
-    }
+    if (page->SweepingDone()) return 0;
+    DCHECK_EQ(Page::kSweepingPending,
+              page->concurrent_sweeping_state().Value());
     page->concurrent_sweeping_state().SetValue(Page::kSweepingInProgress);
     const Sweeper::FreeSpaceTreatmentMode free_space_mode =
         Heap::ShouldZapGarbage() ? ZAP_FREE_SPACE : IGNORE_FREE_SPACE;
     if (identity == NEW_SPACE) {
       RawSweep(page, IGNORE_FREE_LIST, free_space_mode);
     } else {
       max_freed = RawSweep(page, REBUILD_FREE_LIST, free_space_mode);
     }
+    DCHECK(page->SweepingDone());
 
     // After finishing sweeping of a page we clean up its remembered set.
     if (page->typed_old_to_new_slots()) {
       page->typed_old_to_new_slots()->FreeToBeFreedChunks();
     }
     if (page->old_to_new_slots()) {
       page->old_to_new_slots()->FreeToBeFreedBuckets();
     }
+  }
 
-    {
-      base::LockGuard<base::Mutex> guard(&mutex_);
-      swept_list_[identity].Add(page);
-    }
-    page->concurrent_sweeping_state().SetValue(Page::kSweepingDone);
-    page->mutex()->Unlock();
+  {
+    base::LockGuard<base::Mutex> guard(&mutex_);
+    swept_list_[identity].Add(page);
   }
   return max_freed;
 }
 
 void MarkCompactCollector::Sweeper::AddPage(AllocationSpace space, Page* page) {
   DCHECK(!FLAG_concurrent_sweeping || !AreSweeperTasksRunning());
   PrepareToBeSweptPage(space, page);
   sweeping_list_[space].push_back(page);
 }
 
@@ skipping 139 matching lines @@
       // The target is always in old space, we don't have to record the slot in
       // the old-to-new remembered set.
       DCHECK(!heap()->InNewSpace(target));
       RecordRelocSlot(host, &rinfo, target);
     }
   }
 }
 
 }  // namespace internal
 }  // namespace v8