It's reproducible on linux-x64 with:

$ cd jruby
$ ant clean jar compile-test run-junit-precompiled

#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0x00007f7d654fd378, pid=23769, tid=140175328392976
#
# JRE version: 7.0_02-b07
# Java VM: Java HotSpot(TM) 64-Bit Server VM (22.0-b04 mixed mode linux-amd64 )
# Problematic frame:
# V [libjvm.so+0x74d378] PSScavengeRootsClosure::do_oop(oopDesc**)+0x28
#
# Failed to write core dump. Core dumps have been disabled. To enable core dumping, try "ulimit -c unlimited" before starting Java again
#
# If you would like to submit a bug report, please visit:
# http://bugreport.sun.com/bugreport/crash.jsp
#


Stack: [0x00007f7d1c97b000,0x00007f7d1ca7c000], sp=0x00007f7d1ca7a790, free space=1021k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x74d378] PSScavengeRootsClosure::do_oop(oopDesc**)+0x28
V [libjvm.so+0x44cfa9] frame::oops_interpreted_do(OopClosure*, RegisterMap const*, bool)+0xc9
V [libjvm.so+0x800eba] JavaThread::oops_do(OopClosure*, CodeBlobClosure*)+0x15a
V [libjvm.so+0x74d5f5] ThreadRootsTask::do_it(GCTaskManager*, unsigned int)+0x75
V [libjvm.so+0x47ad30] GCTaskThread::run()+0xf0
V [libjvm.so+0x6edf80] java_start(Thread*)+0x100

JavaThread 0x00007f7d6000a000 (nid = 23773) was being processed
Java frames: (J=compiled Java code, j=interpreted, Vv=VM code)
j java.lang.invoke.MethodHandleImpl$GuardWithCatch.invoke_L5(Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;+14
j java.lang.invoke.MethodHandleImpl$GuardWithCatch.invoke_L5(Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;+11
v ~RichochetBlob
j java.lang.invoke.MethodHandle.invokeWithArguments([Ljava/lang/Object;)Ljava/lang/Object;+57
j org.jruby.runtime.invokedynamic.InvocationLinker.invocationFallback(Lorg/jruby/runtime/invokedynamic/JRubyCallSite;Lorg/jruby/runtime/ThreadContext;Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/builtin/IRubyObject;Ljava/lang/String;Lorg/jruby/runtime/Block;)Lorg/jruby/runtime/builtin/IRubyObject;+185
j $_dot_.test.testLoops.__file__(L$_dot_/test/testLoops;Lorg/jruby/runtime/ThreadContext;Lorg/jruby/runtime/builtin/IRubyObject;[Lorg/jruby/runtime/builtin/IRubyObject;Lorg/jruby/runtime/Block;)Lorg/jruby/runtime/builtin/IRubyObject;+845
j $_dot_.test.testLoops.load(Lorg/jruby/runtime/ThreadContext;Lorg/jruby/runtime/builtin/IRubyObject;Z)Lorg/jruby/runtime/builtin/IRubyObject;+17
<snip>