[PATCH 0/2] arm64: ignore memory outside of the linear range

[Ard Biesheuvel]

On 25 August 2015 at 12:02, Will Deacon <will.deacon at arm.com> wrote:
> On Tue, Aug 25, 2015 at 10:45:01AM +0100, Ard Biesheuvel wrote:
>> On 25 August 2015 at 00:34, Stuart Yoder <stuart.yoder at freescale.com> wrote:
>> >> On Mon, Aug 24, 2015 at 02:58:26PM +0100, Stuart Yoder wrote:
>> >> > Are we sending to stable as well?
>> >>
>> >> I've already pushed the patch out without a Cc stable (it's not a
>> >> regression afaict), so if you want it backported then you'll need to send
>> >> it to stable separately.
>> >
>> > Ok, was asking because of Catalin's previous comment:
>> >
>> >  > Even though it is not a regression, I think it is a bug fix and it's
>> >  > worth cc'ing stable (though we could push it after 4.3-rc1).
>> >
>>
>> Indeed. Catalin also mentioned that you and he discussed a minimal fix
>> with a cc to stable, only the fix itself was flawed. So let's not make
>> this Stuart's problem, considering that this issue breaks all arm64
>> systems with 32+ GB of RAM if they follow ARM's own recommendation
>> regarding the physical layout of memory.
>>
>> > Ard, are you going to send to stable?
>> >
>>
>> We'll have to wait until the merge window closes, of course, but yes,
>> we should propose it.
>>
>> @Will: what do you think? It would be nice to have you on record with
>> an opinion rather than leaving it up to Stuart.
>
> This isn't something that has *ever* worked with the arm64 kernel,
> right? In which case, it's not a regression, it's more like adding
> support for some systems that we've not supported before.

I am somewhat on the fence on this one, to be honest. The bug has
always existed but since DRAM is upgradeable, it may affect systems
that we do support and are working fine currently.

> Now, given the
> nature of the patch, I'm not against stable, but by the time Stuart
> pointed that out, I'd already pushed the patch and I don't want to
> rebase our 4.3 queue at this stage.
>

Noted. I just wanted to understand whether you had left it out on purpose.

> The best bet is to send this to stable once it's in mainline (i.e. -rc1)
> and I think it makes sense for Stuart to do that, since he is the one
> most interested in having that happen.
>

Indeed. I take Russell's point about fixes being important, but in
this case, I think it can wait until after the merge window.

-- 
Ard.