How to show hidden sysctl tunable?

I’m on a Yocto Linux distribution and I need to set the sysctl tunable kernel.panic_on_rcu_stall to 1. The problem is when I list the elements inside /proc/sys/kernel I have no panic_on_rcu_stall and if I try to set the option anyway I get the folowing error:

# sysctl -w kernel.panic_on_rcu_stall=1
sysctl: error: 'kernel.panic_on_rcu_stall' is an unknown key

I know that the key exist, we can see it on the Linux Kernel documentation, but it also specify that

Currently, these files might (depending on your configuration) show up in /proc/sys/kernel:

And this is all about, what the documentation means by your configuration and how to change it.

I’m using the 4.4.38+linaro Linux kernel.

Thanks in advance.

Answer

Thanks for your comments, Tsyvarev was right, after applying this patch to my kernel recipe in my Yocto project, the option kernel.panic_on_rcu_stall appeared in /proc/sys/kernel.