linux-kernel - Re: [RFC PATCH 00/11] Avoid synchronous TLB invalidation for intermediate page-table entries on arm64

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Message-ID: <f8ba271b-87c0-29ef-1216-77d5d391d5c8@redhat.com>
Date:   Fri, 7 Sep 2018 02:36:08 -0400
From:   Jon Masters <jcm@...hat.com>
To:     Will Deacon <will.deacon@....com>
Cc:     linux-kernel@...r.kernel.org, peterz@...radead.org,
        benh@....ibm.com, torvalds@...ux-foundation.org, npiggin@...il.com,
        catalin.marinas@....com, linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC PATCH 00/11] Avoid synchronous TLB invalidation for
 intermediate page-table entries on arm64

On 09/05/2018 08:28 AM, Will Deacon wrote:
> On Tue, Sep 04, 2018 at 02:38:02PM -0400, Jon Masters wrote:
>> On 08/24/2018 11:52 AM, Will Deacon wrote:
>>
>>> I hacked up this RFC on the back of the recent changes to the mmu_gather
>>> stuff in mainline. It's had a bit of testing and it looks pretty good so
>>> far.
>>
>> I will request the server folks go and test this. You'll probably
>> remember a couple of parts we've seen where aggressive walker caches
>> ended up (correctly) seeing stale page table entries and we had all
>> manner of horrifically hard to debug problems. We have some fairly nice
>> reproducers that were able to find this last time that we can test.
> 
> Cheers, Jon, that would be very helpful. You're probably best off using
> my (rebasing) tlb branch rather than picking the RFC:
> 
>   git://git.kernel.org/pub/scm/linux/kernel/git/will/linux.git tlb
> 
> Let me know if you'd prefer something stable (I can tag it with a date).

That would be useful. I've prodded each of the Arm server SoC vendors I
work with via our weekly call to have them each specifically check this.
A tag would be helpful to that effort I expect. They all claim to be
watching this thread now, so we'll see if they see cabbages here.

Jon.

-- 
Computer Architect | Sent from my Fedora powered laptop