Error on running map reduce job

[Sesha Kumar]

Hi guys,
                I'm having a problem running map reduce jobs in
hadoop. Whenever I try to run a map reduce job, I get the following
exception:

Caused by: org.apache.hadoop.ipc.RemoteException:
org.apache.hadoop.security.AccessControlException: Permission denied:
user=slave, access=EXECUTE,
inode="map_red":master:supergroup:rwx------
        at 
org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.check(FSPermissionChecker.java:199)
        at 
org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.checkTraverse(FSPermissionChecker.java:155)
        at 
org.apache.hadoop.hdfs.server.namenode.FSPermissionChecker.checkPermission(FSPermissionChecker.java:125)
        at 
org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkPermission(FSNamesystem.java:4811)
        at 
org.apache.hadoop.hdfs.server.namenode.FSNamesystem.checkTraverse(FSNamesystem.java:4790)
        at 
org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getFileInfo(FSNamesystem.java:1876)
        at 
org.apache.hadoop.hdfs.server.namenode.NameNode.getFileInfo(NameNode.java:747)

Note: this is not the entire stack trace.

I found that this occurred because of the directory "/map_red" inside
HDFS does not have necessary permissions.

I use the command "hadoop fs -chmod -R" to change the permissions of
/map_red to 777 after which the map reduce job works properly.

Next time a map reduce job runs, the permissions are reverted back to
rwx------, i need to do the same thing again to get it working.

Is there any way to ensure that the permissions of /map_red always
remain as rwxrwxrwx?

I've included the necessary contents of mapred-site.xml are this:

...
...
   <property>
        <name>mapred.temp.dir</name>
        <value>/map_red_temp</value>
    </property>
    <property>
        <name>mapred.system.dir</name>
        <value>/map_red</value>
    </property>
...
...