Disallowing perf_event_open()

Somehow, I get the impression some kernel developers have disconnected from reality. Or maybe live in a different one, that consists only of developer workstations, back-end systems and maybe super-computing. Obviously, perf is always fine and useful in this reality.

However, there is a significant, other reality that has nasty places like regular end user devices (usually called "smartp hones") or even shared hosting environments.

The latter ones face malicious code and malicious, local users on a daily basis. The operating system running them needs to cope with this or it is simply unfit for this purpose.
Nowadays, mainline Linux *is* unfit for such environments - and the unavoidable perf is a major reason for this.

Now, if this were about removing perf from the kernel, I could understand the opposition. But it is simply about giving the option to disable it. Arguing that "bugs will be fixed" is irrelevant: The risk is still increased. Arguing that administrators are clueless is hubris: Experienced administrators are lazy. If the default configuration works for them, they stick with it. If they change it - or even start patching the kernel - there must be a very good reason and kernel developer would be well-advised to try to understand it.