IopGetMaxValidSectionSize

VOID __fastcall IopGetMaxValidSectionSize(UINT64 Base, UINT64 MaxSize){
  unsigned int v2; 
  unsigned int i; 

  v2 = 0;
  for( i = MaxSize; v2 < i; ++v2 )
  {
    if( !MmIsAddressValidEx(Base + v2) )
      break;
  }
}

Referenced by:

KeCapturePersistentThreadState