failed to execute /bin/bash: Resource temporarily unavailable（Linux系统root无法通过su切换到某个普通用户）

[root@127.0.0.1 config]# su - mform 
Last login: Mon Apr 16 14:08:05 CST 2018 on pts/4
su: failed to execute /bin/bash: Resource temporarily unavailable
[root@127.0.0.1 config]# 
[root@127.0.0.1 config]# 
[root@127.0.0.1 config]# egrep -v "^$|^#" /etc/security/limits.d/20-nproc.conf
*          soft    nproc     4096
root       soft    nproc     unlimited
[root@127.0.0.1 config]# su - mform 
Last login: Mon Apr 16 14:16:25 CST 2018 on pts/4
su: failed to execute /bin/bash: Resource temporarily unavailable
[root@127.0.0.1 config]# 
[root@127.0.0.1 config]# 

[root@127.0.0.1 config]# 

#将默认值4096改为8192

[root@127.0.0.1 config]# vim  /etc/security/limits.d/20-nproc.conf 
[root@127.0.0.1 config]# egrep -v "^$|^#" /etc/security/limits.d/20-nproc.conf
*          soft    nproc     8192
root       soft    nproc     unlimited
[root@127.0.0.1 config]# su - mform 
Last login: Mon Apr 16 14:16:49 CST 2018 on pts/4
[mform@127.0.0.1 ~]$ id
uid=1002(mform) gid=1003(mform) groups=1003(mform)