We've seen several nightly crashes like this:

#
# A fatal error has been detected by the Java Runtime Environment:
#
# SIGSEGV (0xb) at pc=0xffffffff7d13aff8, pid=1043, tid=11
#
# JRE version: 7.0-b129
# Java VM: Java HotSpot(TM) 64-Bit Server VM (21.0-b02-internal-201102142244.kvn.main_to_comp-fastdebug mixed mode solaris-sparc compressed oops)
# Problematic frame:
# V [libjvm.so+0x53aff8] ciObject*ciObjectFactory::get(oop)+0x10b8
#
# Core dump written. Default location: /export/local/42660.JDK7.NIGHTLY.VM+solaris-sparcv9_vm_server_mixed_nsk.stress.testlist/results/ResultDir/jck122001/core or core.1043
#
# If you would like to submit a bug report, please visit:
# http://java.sun.com/webapps/bugreport/crash.jsp
#

Stack: [0xffffffff5df00000,0xffffffff5e000000], sp=0xffffffff5dff6bd0, free space=986k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x53aff8] ciObject*ciObjectFactory::get(oop)+0x10b8;; ciObject*ciObjectFactory::get(oop)+0x10b8
V [libjvm.so+0x4f9210] void ciField::initialize_from(fieldDescriptor*)+0xc90;; void ciField::initialize_from(fieldDescriptor*)+0xc90
V [libjvm.so+0x4f83f0] ciField::ciField #Nvariant 1(fieldDescriptor*)+0x628;; ciField::ciField(fieldDescriptor*)+0x628


Vladimir caught this in the debugger and it appeared that the klassOop in this line:

    klassOop k = _holder->get_klassOop();

went bad at it's use here:

        oop o = k->obj_field(_offset);