G1: assert(!_g1->is_obj_dead(obj)) failed: We should not be preserving dead objs

Nightly test failure that has not been seen before:

gc/gctests/RememberedSet

crashes with the assert:

#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/tmp/jprt/P1/B/202649.jcoomes/source/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp:3416), pid=23049, tid=11
# assert(!_g1->is_obj_dead(obj)) failed: We should not be preserving dead objs.
#
# JRE version: 7.0

Link to the results page:

http://sqeweb.sfbay.sun.com/nfs/results/vm/gtee/JDK7/NIGHTLY/VM/2010-08-12/G1_GC_Baseline/vm/solaris-i586/server/mixed/solaris-i586_vm_server_mixed_vm.gc.testlist/analysis.html

Results Directory:

/net/sqenfs-2.sfbay/export2/results/vm/gtee/JDK7/NIGHTLY/VM/2010-08-12/G1_GC_Baseline/vm/solaris-i586/server/mixed/solaris-i586_vm_server_mixed_vm.gc.testlist

Machine: vm-conroe-02.sfbay.sun.com

Stack trace:

Current thread (0x091e8400): VMThread [stack: 0xd4d7f000,0xd4dff000] [id=11]

Stack: [0xd4d7f000,0xd4dff000], sp=0xd4dfd920, free space=1fad4dff000k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x1cdf0b3];; __1cHVMErrorGreport6MpnMoutputStream__v_+0x70b
V [libjvm.so+0x1ce023a];; __1cHVMErrorOreport_and_die6M_v_+0x582
V [libjvm.so+0xab3e01];; __1cPreport_vm_error6Fpkci11_v_+0x5ad
V [libjvm.so+0xc21318];; __1cYRemoveSelfPointerClosureJdo_object6MnDoop__v_+0x7b4
V [libjvm.so+0x1a06039];; __1cPContiguousSpaceTobject_iterate_from6MnJWaterMark_pnNObjectClosure__v_+0x61
V [libjvm.so+0x1a05fb6];; __1cPContiguousSpaceOobject_iterate6MpnNObjectClosure__v_+0x36
V [libjvm.so+0xbffee9];; __1cPG1CollectedHeapbFremove_self_forwarding_pointers6M_v_+0x139
V [libjvm.so+0xc07088];; __1cPG1CollectedHeapXevacuate_collection_set6M_v_+0x19f8
V [libjvm.so+0xbfd2ce];; __1cPG1CollectedHeapbGdo_collection_pause_at_safepoint6Md_v_+0x546
V [libjvm.so+0x1d1ef95];; __1cXVM_G1IncCollectionPauseEdoit6M_v_+0x10d
V [libjvm.so+0x1d1c8dd];; __1cMVM_OperationIevaluate6M_v_+0xe1
V [libjvm.so+0x1d1a5f5];; __1cIVMThreadSevaluate_operation6MpnMVM_Operation__v_+0x145
V [libjvm.so+0x1d1adb1];; __1cIVMThreadEloop6M_v_+0x5c5
V [libjvm.so+0x1d1a1d5];; __1cIVMThreadDrun6M_v_+0xc1
V [libjvm.so+0x17d93d8];; java_start+0x708
C [libc.so.1+0xa7055];; _thr_setup+0x4e
C [libc.so.1+0xa7340];; _lwp_start+0x0