ubuntu 14.04 （trusty）如何给非 root 用户设置 ulimit 打开文件数

➜ sudo sysctl -a|grep file
fs.file-max = 2037581
fs.file-nr = 2784 0 2037581

➜ ~ cat /proc/sys/fs/file-max
2037581
➜ ~ cat /proc/sys/fs/file-nr
2720 0 2037581

/etc/security/limits.conf
* hard nofile 2037581
* soft nofile 2037581
root hard nofile 2037581
root soft nofile 2037581

/etc/pam.d/su
session required pam_limits.so

/etc/pam.d/common-session
session required pam_limits.so

reboot后仍然只能ulimit -n 4096， 再大就报
ulimit: value exceeds hard limit