linux-kernel - Re: [PATCHv7 02/14] mm: Add support for unaccepted memory

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Message-ID: <fb58de71-a255-364b-5d32-1c839ed4a5c2@redhat.com>
Date:   Tue, 26 Jul 2022 16:30:55 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Borislav Petkov <bp@...en8.de>
Cc:     Dave Hansen <dave.hansen@...el.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Sean Christopherson <seanjc@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Joerg Roedel <jroedel@...e.de>,
        Ard Biesheuvel <ardb@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@...ux.intel.com>,
        David Rientjes <rientjes@...gle.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Tom Lendacky <thomas.lendacky@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Ingo Molnar <mingo@...hat.com>,
        Varad Gautam <varad.gautam@...e.com>,
        Dario Faggioli <dfaggioli@...e.com>,
        Mike Rapoport <rppt@...nel.org>, marcelo.cerri@...onical.com,
        tim.gardner@...onical.com, khalid.elmously@...onical.com,
        philip.cox@...onical.com, x86@...nel.org, linux-mm@...ck.org,
        linux-coco@...ts.linux.dev, linux-efi@...r.kernel.org,
        linux-kernel@...r.kernel.org, Mike Rapoport <rppt@...ux.ibm.com>
Subject: Re: [PATCHv7 02/14] mm: Add support for unaccepted memory

On 25.07.22 14:53, Borislav Petkov wrote:
> On Mon, Jul 25, 2022 at 02:38:57PM +0200, David Hildenbrand wrote:
>> The less core-MM code to handle unaccepted memory the better. Meaning,
>> that any kind of additional pre-acceptance (in addition to what we have
>> here) needs good justification.
> 
> I actually mean to have a user interface to have the core code
> pre-accept. I.e., interface to what will be already there anyway.
>

Ah, got it. The "issue" with ordinary prefaulting in user space is that
you'll also end up zeroing the memory. But yeah, it should just accept a
bunch of memory.

> Or is that frowned upon too?

I was assuming you'd want some additional interface that only accept
memory without actually temporarily allocating it.

-- 
Thanks,

David / dhildenb