linux-kernel - Re: [PATCH] x86/mm/64: Fix an incorrect warning with CONFIG_DEBUG

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Message-ID: <CALCETrWbF+hPuY7rNTKSu=uUdPzUsyHZLFDgWx8D2pVa3TfC6A@mail.gmail.com>
Date:   Sun, 10 Sep 2017 12:10:24 -0700
From:   Andy Lutomirski <luto@...nel.org>
To:     Andy Lutomirski <luto@...nel.org>
Cc:     X86 ML <x86@...nel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Borislav Petkov <bp@...en8.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH] x86/mm/64: Fix an incorrect warning with
 CONFIG_DEBUG_VM=y, !PCID

On Sun, Sep 10, 2017 at 8:52 AM, Andy Lutomirski <luto@...nel.org> wrote:
> I've been staring at the word PCID too long.
>
> Fixes: f13c8e8c58ba ("x86/mm: Reinitialize TLB state on hotplug and resume")
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> Signed-off-by: Andy Lutomirski <luto@...nel.org>
> ---
>  arch/x86/mm/tlb.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/x86/mm/tlb.c b/arch/x86/mm/tlb.c
> index 158acdad2773..1ab3821f9e26 100644
> --- a/arch/x86/mm/tlb.c
> +++ b/arch/x86/mm/tlb.c
> @@ -261,7 +261,7 @@ void initialize_tlbstate_and_flush(void)
>          * doesn't work like other CR4 bits because it can only be set from
>          * long mode.)
>          */
> -       WARN_ON(boot_cpu_has(X86_CR4_PCIDE) &&
> +       WARN_ON(boot_cpu_has(X86_FEATURE_PCID) &&
>                 !(cr4_read_shadow() & X86_CR4_PCIDE));
>
>         /* Force ASID 0 and force a TLB flush. */
> --
> 2.13.5
>

Ugh, don't apply this.  There's a somewhat deeper problem here.