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6722112: CMS: Incorrect encoding of overflown object arrays during concurrent precleaning

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When an object array overflows during precleaning, we should have been marking the entire array dirty, not just its first card.

Reviewed-by: jmasa, poonam, tonyp
This commit is contained in:
Y. Srinivas Ramakrishna 2008-08-14 17:58:35 -07:00
parent 6144fe8e3e
commit 57dabb4fcb
1 changed files with 19 additions and 8 deletions
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27
hotspot/src/share/vm/gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.cpp
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@ -6867,11 +6867,9 @@ void MarkFromRootsClosure::do_bit(size_t offset) {
// during the preclean or remark phase. (CMSCleanOnEnter)
if (CMSCleanOnEnter) {
size_t sz = _collector->block_size_using_printezis_bits(addr);
HeapWord* start_card_addr = (HeapWord*)round_down(
(intptr_t)addr, CardTableModRefBS::card_size);
HeapWord* end_card_addr = (HeapWord*)round_to(
(intptr_t)(addr+sz), CardTableModRefBS::card_size);
MemRegion redirty_range = MemRegion(start_card_addr, end_card_addr);
MemRegion redirty_range = MemRegion(addr, end_card_addr);
assert(!redirty_range.is_empty(), "Arithmetical tautology");
// Bump _threshold to end_card_addr; note that
// _threshold cannot possibly exceed end_card_addr, anyhow.
@ -7460,12 +7458,25 @@ void PushAndMarkClosure::do_oop(oop obj) {
)
if (simulate_overflow || !_mark_stack->push(obj)) {
if (_concurrent_precleaning) {
// During precleaning we can just dirty the appropriate card
// During precleaning we can just dirty the appropriate card(s)
// in the mod union table, thus ensuring that the object remains
// in the grey set and continue. Note that no one can be intefering
// with us in this action of dirtying the mod union table, so
// no locking is required.
_mod_union_table->mark(addr);
// in the grey set and continue. In the case of object arrays
// we need to dirty all of the cards that the object spans,
// since the rescan of object arrays will be limited to the
// dirty cards.
// Note that no one can be intefering with us in this action
// of dirtying the mod union table, so no locking or atomics
// are required.
if (obj->is_objArray()) {
size_t sz = obj->size();
HeapWord* end_card_addr = (HeapWord*)round_to(
(intptr_t)(addr+sz), CardTableModRefBS::card_size);
MemRegion redirty_range = MemRegion(addr, end_card_addr);
assert(!redirty_range.is_empty(), "Arithmetical tautology");
_mod_union_table->mark_range(redirty_range);
} else {
_mod_union_table->mark(addr);
}
_collector->_ser_pmc_preclean_ovflw++;
} else {
// During the remark phase, we need to remember this oop