src/share/vm/gc_implementation/g1/g1CardCounts.cpp

rev 4650 : 8014408: G1: crashes with assert assert(prev_committed_card_num == _committed_max_card_num) failed
Summary: Mismatch in the card number calculation between next and previous committed sizes of the card counts table.
Reviewed-by:

*** 99,122 ****
  
    assert(_committed_size ==
           ReservedSpace::allocation_align_size_up(_committed_size),
           err_msg("Unaligned? committed_size: " SIZE_FORMAT, _committed_size));
  
!   // Verify that the committed space for the card counts
!   // matches our committed max card num.
    size_t prev_committed_size = _committed_size;
!   size_t prev_committed_card_num = prev_committed_size / sizeof(jbyte);
    assert(prev_committed_card_num == _committed_max_card_num,
           err_msg("Card mismatch: "
                   "prev: " SIZE_FORMAT ", "
!                  "committed: "SIZE_FORMAT,
!                  prev_committed_card_num, _committed_max_card_num));
  
    size_t new_size = (heap_capacity >> CardTableModRefBS::card_shift) * sizeof(jbyte);
    size_t new_committed_size = ReservedSpace::allocation_align_size_up(new_size);
!   size_t new_committed_card_num =
!                 MIN2(_reserved_max_card_num, new_committed_size / sizeof(jbyte));
  
    if (_committed_max_card_num < new_committed_card_num) {
      // we need to expand the backing store for the card counts
      size_t expand_size = new_committed_size - prev_committed_size;
  
--- 99,125 ----
  
    assert(_committed_size ==
           ReservedSpace::allocation_align_size_up(_committed_size),
           err_msg("Unaligned? committed_size: " SIZE_FORMAT, _committed_size));
  
!   // Verify that the committed space for the card counts matches our
!   // committed max card num. Note for some allocation alignments, the
!   // amount of space actually committed for the counts table will be able
!   // to span more cards than the number spanned by the maximum heap.
    size_t prev_committed_size = _committed_size;
!   size_t prev_committed_card_num = committed_to_card_num(prev_committed_size);
! 
    assert(prev_committed_card_num == _committed_max_card_num,
           err_msg("Card mismatch: "
                   "prev: " SIZE_FORMAT ", "
!                  "committed: "SIZE_FORMAT", "
!                  "reserved: "SIZE_FORMAT,
!                  prev_committed_card_num, _committed_max_card_num, _reserved_max_card_num));
  
    size_t new_size = (heap_capacity >> CardTableModRefBS::card_shift) * sizeof(jbyte);
    size_t new_committed_size = ReservedSpace::allocation_align_size_up(new_size);
!   size_t new_committed_card_num = committed_to_card_num(new_committed_size);
  
    if (_committed_max_card_num < new_committed_card_num) {
      // we need to expand the backing store for the card counts
      size_t expand_size = new_committed_size - prev_committed_size;