Don't set limit nofile to unlimited

After I set nofile to unlimited in /etc/security/limits.d/90-nproc.conf like this,

*          hard    nproc     unlimited
*          hard    nofile    unlimited

*          soft    nproc     unlimited
*          soft    nofile    unlimited

I could not boot into Gnome on my VM running CentOS 6.8 any more. Even I could switch to a terminal using ctrl-alt-F2, I seemed not be able to log in. I reboot the VM using a live-cd ISO. Then mount the file system, after setting to 32K as below, reboot it, the problem was fixed.

*          -    nproc     unlimited
*          -    nofile    32768

Notes:

# find out the logical volume of the hard drive
fdisk -l

# mount the logical volume
mkdir /mnt/hd
mount /dev/mapper/Volume-lv_root /mnt/hd
vi /mnt/hd/etc/security/limits.d/90-nproc.conf

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