Subject: Re: [PATCH 04/36] cpuidle,intel_idle: Fix CPUIDLE_FLAG_IRQ_ENABLE

From: Michel Lespinasse <[email-masked]>
Date: Mon, 25 Jul 2022 12:43:06 -0700

On Wed, Jun 08, 2022 at 04:27:27PM +0200, Peter Zijlstra wrote:
> Commit c227233ad64c ("intel_idle: enable interrupts before C1 on
> Xeons") wrecked intel_idle in two ways:
> 
>  - must not have tracing in idle functions
>  - must return with IRQs disabled
> 
> Additionally, it added a branch for no good reason.
> 
> Fixes: c227233ad64c ("intel_idle: enable interrupts before C1 on Xeons")
> Signed-off-by: Peter Zijlstra (Intel) <[email-masked]>

After this change was introduced, I am seeing "WARNING: suspicious RCU
usage" when booting a kernel with debug options compiled in. Please
see the attached dmesg output. The issue starts with commit 32d4fd5751ea
and is still present in v5.19-rc8.

I'm not sure, is this too late to fix or revert in v5.19 final ?

Thanks,

--
Michel "walken" Lespinasse