Following failure reported with JDK 15 CI testing -
test - runtime/NMT/ThreadedVirtualAllocTestType.java

  with linux-x64-debug
  with -Xcomp -XX:+CreateCoredumpOnCrash -ea -esa -XX:CompileThreshold=100 -XX:+UnlockExperimentalVMOptions -server -XX:-TieredCompilation -XX:-UseCompressedOops


      ExitCode: 134
      Crash: Internal Error ...memReporter.cpp...assert(committed >= used + free) failed: Sanity
      Crash: V ...[libjvm.so+...] MemSummaryReporter::report_summary_of_type(MemoryType, MallocMemory*, VirtualMemory*)+...


------------------
# A fatal error has been detected by the Java Runtime Environment:
#
# Internal Error (open/src/hotspot/share/services/memReporter.cpp:226), pid=1437, tid=1609
# assert(committed >= used + free) failed: Sanity
#
# JRE version: Java(TM) SE Runtime Environment (15.0+8) (fastdebug build 15-ea+8-182)
# Java VM: Java HotSpot(TM) 64-Bit Server VM (fastdebug 15-ea+8-182, compiled mode, g1 gc, linux-amd64)
# Problematic frame:
# V [libjvm.so+0x112f1d0] MemSummaryReporter::report_summary_of_type(MemoryType, MallocMemory*, VirtualMemory*)+0xab0
#
..............
--------------- T H R E A D ---------------

Current thread (0x00007f1bac001000): JavaThread "Attach Listener" daemon [_thread_in_vm, id=1609, stack(0x00007f1b9f8fa000,0x00007f1b9f9fb000)]

Stack: [0x00007f1b9f8fa000,0x00007f1b9f9fb000], sp=0x00007f1b9f9f91d0, free space=1020k
Native frames: (J=compiled Java code, A=aot compiled Java code, j=interpreted, Vv=VM code, C=native code)
V [libjvm.so+0x112f1d0] MemSummaryReporter::report_summary_of_type(MemoryType, MallocMemory*, VirtualMemory*)+0xab0
V [libjvm.so+0x112f5cc] MemSummaryReporter::report()+0x33c
V [libjvm.so+0x11f9455] NMTDCmd::report(bool, unsigned long)+0x4c5
V [libjvm.so+0x11f9ec8] NMTDCmd::execute(DCmdSource, Thread*)+0x448
V [libjvm.so+0x988ea7] DCmd::parse_and_execute(DCmdSource, outputStream*, char const*, char, Thread*)+0x1d7
V [libjvm.so+0x534307] jcmd(AttachOperation*, outputStream*)+0x47
V [libjvm.so+0x536515] attach_listener_thread_entry(JavaThread*, Thread*)+0x3c5
V [libjvm.so+0x1534136] JavaThread::thread_main_inner()+0x226
V [libjvm.so+0x15392c6] Thread::call_run()+0xf6
V [libjvm.so+0x126ecce] thread_native_entry(Thread*)+0x10e