linux-kernel - Re: [PATCH] x86/mm: Drop usage of __flush_tlb_all() in kernel_physical_mapping

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Message-ID: <CAPcyv4iuRMJjEKutcvRSFjpiy8N27jggUQA-uWd3q7Gopa=xFg@mail.gmail.com>
Date:   Mon, 19 Nov 2018 15:48:33 -0800
From:   Dan Williams <dan.j.williams@...el.com>
To:     Dave Hansen <dave.hansen@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Borislav Petkov <bp@...en8.de>,
        stable <stable@...r.kernel.org>,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        X86 ML <x86@...nel.org>, Ingo Molnar <mingo@...hat.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86/mm: Drop usage of __flush_tlb_all() in kernel_physical_mapping_init()

On Mon, Nov 19, 2018 at 3:43 PM Dave Hansen <dave.hansen@...el.com> wrote:
>
> On 11/19/18 3:19 PM, Dan Williams wrote:
> > Andy wondered why a path that can sleep was using __flush_tlb_all() [1]
> > and Dave confirmed the expectation for TLB flush is for modifying /
> > invalidating existing pte entries, but not initial population [2].
>
> I _think_ this is OK.
>
> But, could we sprinkle a few WARN_ON_ONCE(p*_present()) calls in there
> to help us sleep at night?

Makes sense, I'll add those for v2.