linux-kernel - Re: [5.0.0 rc3 BUG] possible irq lock inversion dependency detected

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Message-ID: <CABXGCsNaw=mb0YF4Bkd5_CTwMfU=dNZ=RTV96dwO=UQy=n_gOQ@mail.gmail.com>
Date:   Mon, 15 Apr 2019 01:07:28 +0500
From:   Mikhail Gavrilov <mikhail.v.gavrilov@...il.com>
To:     Thomas Gleixner <tglx@...utronix.de>
Cc:     Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
        thomas.lendacky@....com
Subject: Re: [5.0.0 rc3 BUG] possible irq lock inversion dependency detected

On Sun, 14 Apr 2019 at 22:51, Thomas Gleixner <tglx@...utronix.de> wrote:
> Because mails fall through the cracks occasionally.
>
> Does the patch below cure your problem?
>
> Thanks,
>
>         tglx
>
> 8<------------------
> --- a/arch/x86/kernel/process.c
> +++ b/arch/x86/kernel/process.c
> @@ -426,6 +426,8 @@ static __always_inline void __speculatio
>         u64 msr = x86_spec_ctrl_base;
>         bool updmsr = false;
>
> +       lockdep_assert_irqs_disabled();
> +
>         /*
>          * If TIF_SSBD is different, select the proper mitigation
>          * method. Note that if SSBD mitigation is disabled or permanentely
> @@ -477,10 +479,12 @@ static unsigned long speculation_ctrl_up
>
>  void speculation_ctrl_update(unsigned long tif)
>  {
> +       unsigned long flags;
> +
>         /* Forced update. Make sure all relevant TIF flags are different */
> -       preempt_disable();
> +       local_irq_save(flags);
>         __speculation_ctrl_update(~tif, tif);
> -       preempt_enable();
> +       local_irq_restore(flags);
>  }
>
>  /* Called from seccomp/prctl update */

Thanks, with this patch problem was gone.
We have time land it in 5.1?

--
Best Regards,
Mike Gavrilov.