This exception appears every time I try to compile Etherpad on Ubuntu with a OpenVZ kernel

etherpad_exception

java.io.IOException: Cannot run program "cp": java.io.IOException: error=12, Cannot allocate memory
	at java.lang.ProcessBuilder.start(ProcessBuilder.java:460)
	at java.lang.Runtime.exec(Runtime.java:593)
	at java.lang.Runtime.exec(Runtime.java:431)
	at java.lang.Runtime.exec(Runtime.java:328)
	at Main$$anon$2.copyFile$1((virtual file):252)
	at Main$$anon$2.doMake((virtual file):263)
	at Main$$anon$2.<init>((virtual file):337)
	at Main$.main((virtual file):4)
	at Main.main((virtual file))
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
	at java.lang.reflect.Method.invoke(Method.java:597)
	at scala.tools.nsc.ObjectRunner$$anonfun$run$1.apply(ObjectRunner.scala:75)
	at scala.tools.nsc.ObjectRunner$.withContextClassLoader(ObjectRunner.scala:49)
	at scala.tools.nsc.ObjectRunner$.run(ObjectRunner.scala:74)
	at scala.tools.nsc.ScriptRunner$.scala$tools$nsc$ScriptRunner$$runCompiled(ScriptRunner.scala:381)
	at scala.tools.nsc.ScriptRunner$$anonfun$runScript$1.apply(ScriptRunner.scala:414)
	at scala.tools.nsc.ScriptRunner$$anonfun$runScript$1.apply(ScriptRunner.scala:413)
	at scala.tools.nsc.ScriptRunner$.withCompiledScript(ScriptRunner.scala:351)
	at scala.tools.nsc.ScriptRunner$.runScript(ScriptRunner.scala:413)
	at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:168)
	at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)
Caused by: java.io.IOException: java.io.IOException: error=12, Cannot allocate memory
	at java.lang.UNIXProcess.<init>(UNIXProcess.java:148)
	at java.lang.ProcessImpl.start(ProcessImpl.java:65)
	at java.lang.ProcessBuilder.start(ProcessBuilder.java:453)
	... 22 more