A number of tests fail with OutOfMemoryError in PermGen, though PermGen is not exhausted.
GC debug output shows no PermGen space exhaustion. Here it is just before described situation:
{Heap before GC invocations=383 (full 177):
 PSYoungGen total 58688K, used 645K [0xf7800000, 0xfb200000, 0xfb200000)
  eden space 57984K, 0% used [0xf7800000,0xf7800000,0xfb0a0000)
  from space 704K, 91% used [0xfb150000,0xfb1f15a8,0xfb200000)
  to space 704K, 0% used [0xfb0a0000,0xfb0a0000,0xfb150000)
 PSOldGen total 466944K, used 824K [0xdb000000, 0xf7800000, 0xf7800000)
  object space 466944K, 0% used [0xdb000000,0xdb0ce038,0xf7800000)
 PSPermGen total 22528K, used 22527K [0xd9a00000, 0xdb000000, 0xdb000000)
  object space 22528K, 99% used [0xd9a00000,0xdafffcd0,0xdb000000)
 [PSYoungGen: 645K->0K(58688K)] [PSOldGen: 824K->1145K(466944K)] 1469K->1145K(525632K) [PSPermGen: 22527K->3321K(22528K)], 0.0409780 secs]
Heap after GC invocations=383 (full 177):
 PSYoungGen total 58688K, used 0K [0xf7800000, 0xfb200000, 0xfb200000)
  eden space 57984K, 0% used [0xf7800000,0xf7800000,0xfb0a0000)
  from space 704K, 0% used [0xfb150000,0xfb150000,0xfb200000)
  to space 704K, 0% used [0xfb0a0000,0xfb0a0000,0xfb150000)
 PSOldGen total 466944K, used 1145K [0xdb000000, 0xf7800000, 0xf7800000)
  object space 466944K, 0% used [0xdb000000,0xdb11e7d0,0xf7800000)
 PSPermGen total 22528K, used 3321K [0xd9a00000, 0xdb000000, 0xdb000000)
  object space 22528K, 14% used [0xd9a00000,0xd9d3e750,0xdb000000)
}

During test execution, swap space exhaustion is observed.

In some cases inspite of throwing OOME JVM can crash with the following messages:

# An unexpected error has been detected by Java Runtime Environment:
#
# SIGBUS (0xa) at pc=0xfc40c4c8, pid=17847, tid=3146
#
# Java VM: Java HotSpot(TM) Server VM (1.6.0-beta2-b80 mixed mode)
# Problematic frame:
# j java.lang.OutOfMemoryError.<init>()V+0

or

# java.lang.OutOfMemoryError: requested 11302 bytes for u1 in /BUILD_AREA/jdk6.0/hotspot/src/share/vm/runtime/classFileParser.cpp. Out of swap space?
#
# Internal Error (/BUILD_AREA/jdk6.0/hotspot/src/share/vm/memory/allocation.inline.hpp, 23 [ Patched ]), pid=18467, tid=2970
#
# Java VM: Java HotSpot(TM) Server VM (1.6.0-beta2-fastdebug-b80-debug mixed mode)

How to reproduce:
    1. Go to /net/vmsqe-amd-01.russia/export2/homes/vi158347/OOME_In_PermGen
    2. Specify tested JDK in JAVA_HOME environment variable
    3. Run reproduce.sh
Optional:
    additional JVM flags can be passed through EXT_FLAGS variable

Also, a number of hs_err* files generated after crashes are stored with reproduce script.

Affected tests:
    runtime/ParallelClassLoading/mixed/combine/forName/mixed_2
    runtime/ParallelClassLoading/mixed/combine/forName/mixed_3
    runtime/ParallelClassLoading/mixed/combine/forName/mixed_4
    runtime/ParallelClassLoading/mixed/combine/forName/mixed_5
    runtime/ParallelClassLoading/mixed/combine/forName/mixed_6
    runtime/ParallelClassLoading/mixed/combine/forName/mixed_7
    runtime/ParallelClassLoading/mixed/combine/forName/mixed_8
    runtime/ParallelClassLoading/mixed/combine/forName/mixed_9
    runtime/ParallelClassLoading/mixed/combine/forName/mixed_10
    runtime/ParallelClassLoading/mixed/combine/loadClass/mixed_2
    runtime/ParallelClassLoading/mixed/combine/loadClass/mixed_3
    runtime/ParallelClassLoading/mixed/combine/loadClass/mixed_4
    runtime/ParallelClassLoading/mixed/combine/loadClass/mixed_5
    runtime/ParallelClassLoading/mixed/combine/loadClass/mixed_6
    runtime/ParallelClassLoading/mixed/combine/loadClass/mixed_7
    runtime/ParallelClassLoading/mixed/combine/loadClass/mixed_8
    runtime/ParallelClassLoading/mixed/combine/loadClass/mixed_9
    runtime/ParallelClassLoading/mixed/combine/loadClass/mixed_10