Mercurial > hg > graal-jvmci-8
diff src/share/vm/gc_implementation/g1/heapRegion.cpp @ 20652:e8bf410d5e23
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 80ac3ee51955 b554c7fa9478 |
line wrap: on
line diff
--- a/src/share/vm/gc_implementation/g1/heapRegion.cpp Tue Nov 11 11:05:41 2014 +0100 +++ b/src/share/vm/gc_implementation/g1/heapRegion.cpp Fri Nov 14 14:23:25 2014 +0100 @@ -1015,10 +1015,13 @@ HeapWord* G1OffsetTableContigSpace::saved_mark_word() const { G1CollectedHeap* g1h = G1CollectedHeap::heap(); assert( _gc_time_stamp <= g1h->get_gc_time_stamp(), "invariant" ); - if (_gc_time_stamp < g1h->get_gc_time_stamp()) - return top(); - else + HeapWord* local_top = top(); + OrderAccess::loadload(); + if (_gc_time_stamp < g1h->get_gc_time_stamp()) { + return local_top; + } else { return Space::saved_mark_word(); + } } void G1OffsetTableContigSpace::record_top_and_timestamp() {