linux-kernel - Re: [PATCH v3 1/5] mm: Optimize mprotect() by batch-skipping PTEs

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Message-ID: <8c389ee5-f7a4-44f6-a0d6-cc01c3da4d91@redhat.com>
Date: Thu, 22 May 2025 18:18:56 +0200
From: David Hildenbrand <david@...hat.com>
To: Dev Jain <dev.jain@....com>, akpm@...ux-foundation.org
Cc: ryan.roberts@....com, willy@...radead.org, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, catalin.marinas@....com, will@...nel.org,
 Liam.Howlett@...cle.com, lorenzo.stoakes@...cle.com, vbabka@...e.cz,
 jannh@...gle.com, anshuman.khandual@....com, peterx@...hat.com,
 joey.gouly@....com, ioworker0@...il.com, baohua@...nel.org,
 kevin.brodsky@....com, quic_zhenhuah@...cinc.com,
 christophe.leroy@...roup.eu, yangyicong@...ilicon.com,
 linux-arm-kernel@...ts.infradead.org, hughd@...gle.com,
 yang@...amperecomputing.com, ziy@...dia.com
Subject: Re: [PATCH v3 1/5] mm: Optimize mprotect() by batch-skipping PTEs

On 22.05.25 09:47, Dev Jain wrote:
> 
> On 22/05/25 12:43 pm, David Hildenbrand wrote:
>>
>>>> ... likely with a better function name,
>>>
>>>
>>> I want to be able to reuse the folio from vm_normal_folio(), and we also
>>> need
>>>
>>> nr_ptes to know how much to skip, so if there is no objection in passing
>>> int *nr_ptes,
>>>
>>> or struct folio **foliop to this new function, then I'll carry on with
>>> your suggestion :)
>>
>> Can you quickly prototype what you have in mind and paste it here?
>> Will make it easier :)
> 
> 
> if (prot_numa)
> 
>       func(vma, addr, oldpte, &nr);

I'd probably return "nr_ptes" and return the folio using a &folio instead.

That way, you can easily extend the function to return the folio in the 
patch where you really need it (not this patch IIUR :) )

-- 
Cheers,

David / dhildenb