runThese crashed with following assert during PIT for 8u20-b16 with G1 GC and client compiler on linux-i586:

;; Using jvm: "/scratch/local/aurora/sandbox/sca/vmsqe/jdk/pit/2014-05-23-212501.jcoomes.hs25-20-b16-snapshot/fastdebug/linux-i586/jre/lib/i386/client/libjvm.so"
#
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (/opt/jprt/T/P1/212501.jcoomes/s/src/share/vm/gc_implementation/g1/concurrentMark.inline.hpp:326), pid=19435, tid=3994913648
# assert(obj->is_oop_or_null(true )) failed: Error
#
# JRE version: Java(TM) SE Runtime Environment (8.0_20-b15) (build 1.8.0_20-ea-fastdebug-b15)
# Java VM: Java HotSpot(TM) Client VM (25.20-b16-internal-201405232125.jcoomes.hs25-20-b16-snapsho-fastdebug mixed mode linux-x86 )
# Core dump written. Default location: /scratch/local/aurora/sandbox/results/runThese/core or core.19435
#
# If you would like to submit a bug report, please visit:
# http://bugreport.sun.com/bugreport/crash.jsp
#

--------------- T H R E A D ---------------

Current thread (0xf35d8800): ConcurrentGCThread [stack: 0xee158000,0xee1d9000] [id=19512]

Stack: [0xee158000,0xee1d9000], sp=0xee1d7ba0, free space=510k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x99ff35] VMError::report_and_die()+0x185;; VMError::report_and_die()+0x185
V [libjvm.so+0x377608] report_vm_error(char const*, int, char const*, char const*)+0x68;; report_vm_error(char const*, int, char const*, char const*)+0x68
V [libjvm.so+0x4aa552] void G1CMOopClosure::do_oop_nv<oop>(oop*)+0x142;; void G1CMOopClosure::do_oop_nv<oop>(oop*)+0x142
V [libjvm.so+0x7c01dc] ObjArrayKlass::oop_oop_iterate_nv(oop, G1CMOopClosure*)+0x9c;; ObjArrayKlass::oop_oop_iterate_nv(oop, G1CMOopClosure*)+0x9c
V [libjvm.so+0x32da56] CMTask::scan_object(oop)+0xe6;; CMTask::scan_object(oop)+0xe6
V [libjvm.so+0x335562] CMBitMapClosure::do_bit(unsigned int)+0x112;; CMBitMapClosure::do_bit(unsigned int)+0x112
V [libjvm.so+0x32f908] CMTask::do_marking_step(double, bool, bool)+0xa18;; CMTask::do_marking_step(double, bool, bool)+0xa18
V [libjvm.so+0x337d0c] CMConcurrentMarkingTask::work(unsigned int)+0x3bc;; CMConcurrentMarkingTask::work(unsigned int)+0x3bc
V [libjvm.so+0x9e330b] GangWorker::loop()+0x30b;; GangWorker::loop()+0x30b
V [libjvm.so+0x9e1b58] GangWorker::run()+0x18;; GangWorker::run()+0x18
V [libjvm.so+0x7f2299] java_start(Thread*)+0x119;; java_start(Thread*)+0x119
C [libpthread.so.0+0x6a49]

I was not able to reproduce this crash yet.