linux-kernel - Re: [patch 0/6] x86/idle: Cure RCU violations and cleanups

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Date: Fri, 1 Mar 2024 19:41:57 +0100
From: Borislav Petkov <bp@...en8.de>
To: Thomas Gleixner <tglx@...utronix.de>
Cc: LKML <linux-kernel@...r.kernel.org>, x86@...nel.org,
	Steven Rostedt <rostedt@...dmis.org>,
	"Paul E. McKenney" <paulmck@...nel.org>
Subject: Re: [patch 0/6] x86/idle: Cure RCU violations and cleanups

On Thu, Feb 29, 2024 at 03:23:35PM +0100, Thomas Gleixner wrote:
> Boris reported that a RCU related warning triggers in the tracer code on
> AMD machines which are affected by Erratum 400. On those CPUs the local
> APIC timer stops in the C1E halt state. This is handled by a special idle
> function which invokes tick_broadcast_enter()/exit() around HALT.  These
> functions can end up in lockdep or tracing which use RCU protected data,
> but the core code already set RCU to idle which means that the RCU
> protection is not longer given.
> 
> This series fixes this by handling the tick broadcast conditionally in the
> core idle function. While working on it I noticed a few bogosities in the
> related code and cleaned that up on top.
> 
> The series is also available from git:
> 
>    git://git.kernel.org/pub/scm/linux/kernel/git/tglx/devel.git x86/core
> 
> Thanks,
> 
> 	tglx
> ---
>  arch/x86/Kconfig                 |    1 
>  arch/x86/include/asm/processor.h |    2 
>  arch/x86/kernel/cpu/common.c     |    4 -
>  arch/x86/kernel/process.c        |   89 +++++++++++----------------------------
>  include/linux/cpu.h              |    2 
>  include/linux/tick.h             |    3 +
>  kernel/sched/idle.c              |   21 +++++++++
>  kernel/time/Kconfig              |    5 ++
>  8 files changed, 62 insertions(+), 65 deletions(-)

I refreshed my local branch with all your fixed patches and it still
works.

Tested-by: Borislav Petkov (AMD) <bp@...en8.de>

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette