linux-kernel - Re: [PATCH v1 2/4] mm: smaller folio_pte

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Message-ID: <aGTw5ipC-ITJGfv0@localhost.localdomain>
Date: Wed, 2 Jul 2025 10:42:14 +0200
From: Oscar Salvador <osalvador@...e.de>
To: David Hildenbrand <david@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Vlastimil Babka <vbabka@...e.cz>, Jann Horn <jannh@...gle.com>,
	Mike Rapoport <rppt@...nel.org>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Michal Hocko <mhocko@...e.com>, Zi Yan <ziy@...dia.com>,
	Matthew Brost <matthew.brost@...el.com>,
	Joshua Hahn <joshua.hahnjy@...il.com>, Rakie Kim <rakie.kim@...com>,
	Byungchul Park <byungchul@...com>,
	Gregory Price <gourry@...rry.net>,
	Ying Huang <ying.huang@...ux.alibaba.com>,
	Alistair Popple <apopple@...dia.com>,
	Pedro Falcato <pfalcato@...e.de>, Rik van Riel <riel@...riel.com>,
	Harry Yoo <harry.yoo@...cle.com>
Subject: Re: [PATCH v1 2/4] mm: smaller folio_pte_batch() improvements

On Fri, Jun 27, 2025 at 01:55:08PM +0200, David Hildenbrand wrote:
> Let's clean up a bit:
> 
> (1) No need for start_ptep vs. ptep anymore, we can simply use ptep
> 
> (2) Let's switch to "unsigned int" for everything
> 
> (3) We can simplify the code by leaving the pte unchanged after the
>     pte_same() check.
> 
> (4) Clarify that we should never exceed a single VMA; it indicates a
>     problem in the caller.
> 
> No functional change intended.
> 
> Signed-off-by: David Hildenbrand <david@...hat.com>

Hi David :-),

I have to confess that I fell in the same trap as Lorenzo wrt.
__pte_batch_clear_ignored changing the pte value.
So I'm not sure if it would be nice to place a little comment in
__pte_batch_clear_ignored claryfing that pte's value remains unchanged ?

Reviewed-by: Oscar Salvador <osalvador@...e.de>

 
-- 
Oscar Salvador
SUSE Labs