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

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Message-ID: <279dadae-9148-465c-7ec6-3f37e026c6c9@intel.com>
Date:   Mon, 19 Nov 2018 15:43:23 -0800
From:   Dave Hansen <dave.hansen@...el.com>
To:     Dan Williams <dan.j.williams@...el.com>, tglx@...utronix.de
Cc:     "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@...r.kernel.org,
        Andy Lutomirski <luto@...nel.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>, x86@...nel.org,
        mingo@...hat.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/mm: Drop usage of __flush_tlb_all() in
 kernel_physical_mapping_init()

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?