src/share/vm/gc_implementation/g1/g1PageBasedVirtualSpace.hpp

rev 7618 : 8062063: Usage of UseHugeTLBFS, UseLargePagesInMetaspace and huge SurvivorAlignmentInBytes cause crashes in CMBitMapClosure::do_bit
Summary: Making sure committed memory is cleared when re-committed, even if using large pages.
Reviewed-by:
rev 7619 : [mq]: clear-in-listener
rev 7620 : [mq]: needs-zeroing-to-dirty

*** 47,56 ****
--- 47,62 ----
    size_t _page_size;
  
    // Bitmap used for verification of commit/uncommit operations.
    BitMap _committed;
  
+   // Bitmap used to keep track of which pages are dirty or not for _special
+   // spaces. This is needed because for those spaces the underlying memory
+   // will only be zero filled the first time it is committed. Calls to commit
+   // will use this bitmap and return whether or not the memory is zero filled.
+   BitMap _dirty;
+ 
    // Indicates that the entire space has been committed and pinned in memory,
    // os::commit_memory() or os::uncommit_memory() have no function.
    bool _special;
  
    // Indicates whether the committed space should be executable.
*** 69,84 ****
    bool is_area_uncommitted(uintptr_t start, size_t size_in_pages) const;
  
   public:
  
    // Commit the given area of pages starting at start being size_in_pages large.
!   MemRegion commit(uintptr_t start, size_t size_in_pages);
  
    // Uncommit the given area of pages starting at start being size_in_pages large.
!   MemRegion uncommit(uintptr_t start, size_t size_in_pages);
! 
!   bool special() const { return _special; }
  
    // Initialization
    G1PageBasedVirtualSpace();
    bool initialize_with_granularity(ReservedSpace rs, size_t page_size);
  
--- 75,89 ----
    bool is_area_uncommitted(uintptr_t start, size_t size_in_pages) const;
  
   public:
  
    // Commit the given area of pages starting at start being size_in_pages large.
!   // Returns true if the given area is zero filled upon completion.
!   bool commit(uintptr_t start, size_t size_in_pages);
  
    // Uncommit the given area of pages starting at start being size_in_pages large.
!   void uncommit(uintptr_t start, size_t size_in_pages);
  
    // Initialization
    G1PageBasedVirtualSpace();
    bool initialize_with_granularity(ReservedSpace rs, size_t page_size);