Re: [PATCH 3/6] ftrace/x86: Warn and ignore graph tracing when RCU is disabled

[Peter Zijlstra]

On Mon, Jan 23, 2023 at 05:07:53PM -0500, Steven Rostedt wrote:

> Actually, perhaps we can just add this, and all you need to do is create
> and set CONFIG_NO_RCU_TRACING (or some other name).

Elsewhere I've used CONFIG_ARCH_WANTS_NO_INSTR for this.

Anyway, I took it for a spin and it .... doesn't seems to do the job.

With my patch the first splat is

  "RCU not on for: cpuidle_poll_time+0x0/0x70"

While with yours I seems to get the endless:

  "WARNING: suspicious RCU usage"

thing. Let me see if I can figure out where it goes side-ways.