linux-kernel - Re: [PATCH 0/4] mm: page_ext: Introduce new iteration API

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Message-ID: <b80a15a7-f9ce-49eb-b721-b59f20bd6fac@redhat.com>
Date: Thu, 20 Feb 2025 11:49:20 +0100
From: David Hildenbrand <david@...hat.com>
To: Andrew Morton <akpm@...ux-foundation.org>,
 Luiz Capitulino <luizcap@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, yuzhao@...gle.com,
 pasha.tatashin@...een.com, hannes@...xchg.org, muchun.song@...ux.dev
Subject: Re: [PATCH 0/4] mm: page_ext: Introduce new iteration API

On 20.02.25 00:52, Andrew Morton wrote:
> On Tue, 18 Feb 2025 21:17:46 -0500 Luiz Capitulino <luizcap@...hat.com> wrote:
> 
>> To fix this, this series introduces a new iteration API for page extension
>> objects. The API checks if the next page extension object can be retrieved
>> from the current section or if it needs to look up for it in another
>> section.
>>
>> ...
> 
> A regression since 6.12, so we should backport the fix.
> 
>> ...
>>
>>   include/linux/page_ext.h | 67 +++++++++++++++++++++++++++++++++++++---
>>   mm/page_ext.c            | 48 ++++++++++++++++++++++++++++
>>   mm/page_owner.c          | 61 +++++++++++++++++-------------------
>>   mm/page_table_check.c    | 39 +++++++----------------
>>   4 files changed, 152 insertions(+), 63 deletions(-)
> 
> That's a lot to backport!
> 
> Is there some quick-n-dirty fixup we can apply for the sake of -stable
> kernels, then work on this long-term approach for future kernels?

I assume we could loop in 
reset_page_owner()/page_table_check_free()/set_page_owner()/page_table_check_alloc(). 
Not-so-nice for upstream, maybe good-enough for stable. Still nasty :)

OTOH, we don't really expect a lot of conflicts.

-- 
Cheers,

David / dhildenb