Why does the following “cat” command fail?

Issue

• Why cat /proc/self/attr/current returns Invalid argument when SELinux is disabled?
• With SELinux in disabled mode gives below output :

[nbk15lk@lrchm00dn01 tmp]$  cat /proc/self/attr/current
cat: /proc/self/attr/current: Invalid argument
[nbk15lk@lrchm00dn01 tmp]$ sestatus
SELinux status:                 disabled

• When in enforcing mode gives below output :

[root@rhel6u7-1 ~]# cat /etc/redhat-release 
Red Hat Enterprise Linux Server release 6.8 (Santiago)
[root@rhel6u7-1 ~]# cat /proc/self/attr/current
unconfined_u:unconfined_r:unconfined_t:s0-s0:c0.c1023