System Resource Limits
From Elvanör's Technical Wiki
PAM and /etc/security/limits.conf
- The processes that go through the PAM system have their limits set in /etc/security/limits.conf. If you change these values and reboot, they will be applied.
- Be careful, a common use case is to type "ulimit -a" inside a remote shell via SSH, and if you have "UsePAM No" defined in /etc/ssh/sshd_config, these limits are NOT applied.