How do I enable memory zone reclaim mode on the Linux kernel? I am running Gentoo Linux Hardened using kernel 4.3.3-hardened-r4 on an AMD A4-5300 APU. To troubleshoot a memory problem I have with my system I need to enable `sysctl vm.zone_reclaim_mode=1`, but doing so results in the following error message: sysctl: cannot stat /proc/sys/vm/zone_reclaim_mode: No such file or directory Being this Gentoo, that error message probably means I missed compiling some kernel feature. However, I looked around on the kernel's configuration menu (`make menuconfig`) and couldn't find any option, and the internet wasn't conclusive at all when looking up online how to enable this option. The closest thing I could find was this Linux kernel's documentation page that explains all the configuration files located under `/proc/sys/vm`. What do I have to do to be able to use `vm.zone_reclaim_mode=1`?

I'm answering my own question since it hasn't gotten any answer and the solution suggested on the comments worked like a charm.

I solved this by enabling `CONFIG_NUMA` in my kernel configuration and rebuilding it. After booting my new kernel I could enable `sysctl vm.zone_reclaim_mode=1` without a hitch.