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8044406: JVM crash with JDK8 (build 1.8.0-b132) with G1 GC

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Fill the last card that has been allocated into with a dummy object

Reviewed-by: tschatzl, mgerdin
This commit is contained in:
Poonam Bajaj 2014-08-18 19:30:24 -07:00
parent 17e9dba8e9
commit 2617d54723
3 changed files with 37 additions and 1 deletions
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2
hotspot/src/share/vm/gc_implementation/g1/g1AllocRegion.hpp
View File

@ -173,7 +173,7 @@ public:
// Should be called when we want to release the active region which
// is returned after it's been retired.
HeapRegion* release();
virtual HeapRegion* release();
#if G1_ALLOC_REGION_TRACING
void trace(const char* str, size_t word_size = 0, HeapWord* result = NULL);

29
hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp
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@ -6833,6 +6833,35 @@ void OldGCAllocRegion::retire_region(HeapRegion* alloc_region,
_g1h->retire_gc_alloc_region(alloc_region, allocated_bytes,
GCAllocForTenured);
}
HeapRegion* OldGCAllocRegion::release() {
HeapRegion* cur = get();
if (cur != NULL) {
// Determine how far we are from the next card boundary. If it is smaller than
// the minimum object size we can allocate into, expand into the next card.
HeapWord* top = cur->top();
HeapWord* aligned_top = (HeapWord*)align_ptr_up(top, G1BlockOffsetSharedArray::N_bytes);
size_t to_allocate_words = pointer_delta(aligned_top, top, HeapWordSize);
if (to_allocate_words != 0) {
// We are not at a card boundary. Fill up, possibly into the next, taking the
// end of the region and the minimum object size into account.
to_allocate_words = MIN2(pointer_delta(cur->end(), cur->top(), HeapWordSize),
MAX2(to_allocate_words, G1CollectedHeap::min_fill_size()));
// Skip allocation if there is not enough space to allocate even the smallest
// possible object. In this case this region will not be retained, so the
// original problem cannot occur.
if (to_allocate_words >= G1CollectedHeap::min_fill_size()) {
HeapWord* dummy = attempt_allocation(to_allocate_words, true /* bot_updates */);
CollectedHeap::fill_with_object(dummy, to_allocate_words);
}
}
}
return G1AllocRegion::release();
}
// Heap region set verification
class VerifyRegionListsClosure : public HeapRegionClosure {

7
hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp
View File

@ -183,6 +183,13 @@ protected:
public:
OldGCAllocRegion()
: G1AllocRegion("Old GC Alloc Region", true /* bot_updates */) { }
// This specialization of release() makes sure that the last card that has been
// allocated into has been completely filled by a dummy object.
// This avoids races when remembered set scanning wants to update the BOT of the
// last card in the retained old gc alloc region, and allocation threads
// allocating into that card at the same time.
virtual HeapRegion* release();
};
// The G1 STW is alive closure.