linux-kernel - Re: [RFC PATCH v2 0/7] Introduce persistent memory pool

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Message-ID: <fa924c8d-c954-5612-37eb-43e1976a1b7b@redhat.com>
Date:   Thu, 28 Sep 2023 19:35:32 +0200
From:   David Hildenbrand <david@...hat.com>
To:     Dave Hansen <dave.hansen@...el.com>,
        Stanislav Kinsburskii <skinsburskii@...ux.microsoft.com>,
        Baoquan He <bhe@...hat.com>
Cc:     tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
        ebiederm@...ssion.com, akpm@...ux-foundation.org,
        stanislav.kinsburskii@...il.com, corbet@....net,
        linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
        linux-mm@...ck.org, kys@...rosoft.com, jgowans@...zon.com,
        wei.liu@...nel.org, arnd@...db.de, gregkh@...uxfoundation.org,
        graf@...zon.de, pbonzini@...hat.com
Subject: Re: [RFC PATCH v2 0/7] Introduce persistent memory pool

On 28.09.23 15:22, Dave Hansen wrote:
> On 9/27/23 09:13, Stanislav Kinsburskii wrote:
>> Once deposited, these pages can't be accessed by Linux anymore and thus
>> must be preserved in "used" state across kexec, as hypervisor state is
>> unware of kexec.
> 
> If Linux can't access them, they're not RAM any more.  I'd much rather
> remove them from the memory map and move on with life rather than
> implement a bunch of new ABI that's got to be handed across kernels.

The motivation of handling kexec (faster?) in a hyper-v domain doesn't 
sound particularly compelling got me for such features. If you inflated 
memory, just don't allow to kexec. It's been broken for years IIUC.

Maybe the other use cases are more "relevant".

-- 
Cheers,

David / dhildenb