linux-kernel - Re: [PATCH v5 2/2] mm/arm64: override mkold_clean

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Message-ID: <84eca849-5da3-4272-ade6-dc0f2b3dc4b2@arm.com>
Date: Fri, 12 Apr 2024 12:21:22 +0100
From: Ryan Roberts <ryan.roberts@....com>
To: Lance Yang <ioworker0@...il.com>
Cc: akpm@...ux-foundation.org, david@...hat.com, 21cnbao@...il.com,
 mhocko@...e.com, fengwei.yin@...el.com, zokeefe@...gle.com,
 shy828301@...il.com, xiehuan09@...il.com, wangkefeng.wang@...wei.com,
 songmuchun@...edance.com, peterx@...hat.com, minchan@...nel.org,
 linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 2/2] mm/arm64: override mkold_clean_ptes() batch helper

On 12/04/2024 03:09, Lance Yang wrote:
> On Thu, Apr 11, 2024 at 9:17 PM Ryan Roberts <ryan.roberts@....com> wrote:
>>
>> On 08/04/2024 05:24, Lance Yang wrote:
>>> The per-pte get_and_clear/modify/set approach would result in
>>> unfolding/refolding for contpte mappings on arm64. So we need
>>> to override mkold_clean_ptes() for arm64 to avoid it.
>>
>> IIRC, in the last version, I suggested copying the wrprotect_ptes() pattern to
>> correctly iterate over contpte blocks. I meant for you to take it as inspiration
>> but looks like you have done a carbon copy, including lots of things that are
>> unneeded here. That's my fault for not being clear - sorry!
> 
> My bad. I must have misunderstood your intention.

Not at all - it was my bad. wrprotect_ptes() is nothing like what I eventually
suggested below, so sorry for the bad steer.