linux-kernel - Re: [PATCH v2] virtio_mem: fix panic on mb

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Message-ID: <5adf42d2-649d-adcc-4598-26263ca27a31@gmail.com>
Date:   Tue, 21 Dec 2021 22:24:44 +0800
From:   Eric Ren <renzhengeek@...il.com>
To:     David Hildenbrand <david@...hat.com>, linux-mm@...ck.org
Cc:     linux-kernel@...r.kernel.org, vbabka@...e.cz, ziy@...dia.com
Subject: Re: [PATCH v2] virtio_mem: fix panic on mb_states indexing overflow

Hi David,

在 12/21/21 9:53 PM, David Hildenbrand 写道:
> Hi Eric,
>
>> _vm->sbm.first_mb_id == 0
> ^ that's precisely what I meant.
Ah, finally got it!
>
> How could it *ever* be safe on x86-64 to let a virtio-mem device start
> on physical address 0, eventually overlapping essentially all DMA, the
> BIOS and the PCI hole.
You're right! That clears my doubt why this "issue" can live so long 
there... util I see it.

Yes, my setup is a very hacking enviroment. The device region start addr 
is wrongly
assigned to 0!

So, let's just drop this patch.

Eric
>
> Thus my question: Is this a "fix" for x86-64 or is this a "prepare for"
> for !x86-64 (e.g., arm64).
>
> If it's a fix, we want proper "Fixes:" and "Cc: stable" tags. But I
> assume this is much rather a preparation for another architecture than
> x86-64.
>
> Thanks!
>