@rose @dacmot, actually, no. That's the wrong place: it'll be overwritten when linux-sysctl-defaults (or its Fedora equivalent) is updated. Put that line in a file in /etc/sysctl.d.

(Also, it's actually /usr/lib/sysctl.d/50-default.conf; you just found it via /lib because of the usr-merge shenanigans.)