linux-kernel - Re: [patch 00/18] init: Enable might_sleep() and smp_processor

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Date:   Mon, 15 May 2017 12:53:10 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...nel.org>,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: [patch 00/18] init: Enable might_sleep() and smp_processor_id()
 debugging early

Hi Thomas,

On Sun, May 14, 2017 at 08:27:16PM +0200, Thomas Gleixner wrote:
> We recentlty discovered a call path which takes a mutex from the low level
> secondary CPU bringup code and wondered why this was not caught by
> might_sleep().
> 
> The reason is that both debug facilities depend on system_state ==
> SYSTEM_RUNNING, which is set after init memory is freed.
> 
> That means that the SMP bootup and the builtin driver initialization is not
> covered by these checks at all.
> 
> The patch series addresses this by adding two intermediate
> states. might_sleep() debugging is enabled right when scheduling starts,
> i.e. the boot CPU idle task schedules the first time. smp_processor_id()
> debugging is enabled right before SMP bringup happens.

Thanks for putting this together!

I've tested the series on a Juno R1 (arm64) system, with both DT and
ACPI.

Patch 17 finds the arm64 mutex issue [1] we discussed previously.

Otherwise, no new issues spotted with this on arm64, just an (existing)
ACPI PMU issue for which I've evidently not run sufficient checks on.

So for the bits relevant to arm64 (patches 1, 3, 7, 8, and 12-18):

Tested-by: Mark Rutland <mark.rutland@....com>

Thanks,
Mark.

[1] https://lkml.kernel.org/r/20170511125430.GD14766@leverpostej

> 
> Thanks,
> 
> 	tglx
> ----
>  arch/arm/kernel/smp.c            |    3 +--
>  arch/metag/kernel/smp.c          |    3 +--
>  arch/x86/kernel/smpboot.c        |    2 +-
>  b/arch/arm64/kernel/smp.c        |    3 +--
>  b/arch/powerpc/kernel/smp.c      |    2 +-
>  drivers/acpi/pci_root.c          |    2 +-
>  drivers/base/node.c              |    2 +-
>  drivers/cpufreq/pasemi-cpufreq.c |    2 +-
>  drivers/iommu/intel-iommu.c      |    4 ++--
>  drivers/iommu/of_iommu.c         |    2 +-
>  drivers/xen/manage.c             |    2 ++
>  include/linux/kernel.h           |    2 ++
>  init/main.c                      |   12 ++++++++++--
>  kernel/async.c                   |    8 ++++----
>  kernel/extable.c                 |    2 +-
>  kernel/printk/printk.c           |    2 +-
>  kernel/sched/core.c              |    4 +++-
>  lib/smp_processor_id.c           |    2 +-
>  mm/vmscan.c                      |    2 +-
>  19 files changed, 36 insertions(+), 25 deletions(-)
> 
> 
>