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comparison src/share/vm/gc_implementation/g1/heapRegion.cpp @ 20652:e8bf410d5e23

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8058209: Race in G1 card scanning could allow scanning of memory covered by PLABs Summary: Read _top before _gc_time_stamp in saved_mark_word() with LoadLoad order to ensure we get a consistent view Reviewed-by: brutisso, dcubed, dholmes, stefank
author mgerdin
date Fri, 14 Nov 2014 14:23:25 +0100
parents 0fcaab91d485
children 7848fc12602b
comparison
equal deleted inserted replaced
20651:600c44255e5f 20652:e8bf410d5e23
1013 } 1013 }
1014 1014
1015 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const { 1015 HeapWord* G1OffsetTableContigSpace::saved_mark_word() const {
1016 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 1016 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1017 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" ); 1017 assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" );
1018 if (_gc_time_stamp < g1h->get_gc_time_stamp()) 1018 HeapWord* local_top = top();
1019 return top(); 1019 OrderAccess::loadload();
1020 else 1020 if (_gc_time_stamp < g1h->get_gc_time_stamp()) {
1021 return local_top;
1022 } else {
1021 return Space::saved_mark_word(); 1023 return Space::saved_mark_word();
1024 }
1022 } 1025 }
1023 1026
1024 void G1OffsetTableContigSpace::record_top_and_timestamp() { 1027 void G1OffsetTableContigSpace::record_top_and_timestamp() {
1025 G1CollectedHeap* g1h = G1CollectedHeap::heap(); 1028 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1026 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp(); 1029 unsigned curr_gc_time_stamp = g1h->get_gc_time_stamp();