linux-kernel - Re: [PATCH v2 4/4] mm: page_owner: use new iteration API

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Message-ID: <a8eb1d44-5b11-4127-b79d-8464a3b0cb4c@redhat.com>
Date: Fri, 28 Feb 2025 10:09:35 +0100
From: David Hildenbrand <david@...hat.com>
To: Luiz Capitulino <luizcap@...hat.com>, linux-kernel@...r.kernel.org,
 linux-mm@...ck.org, yuzhao@...gle.com, pasha.tatashin@...een.com
Cc: akpm@...ux-foundation.org, hannes@...xchg.org, muchun.song@...ux.dev
Subject: Re: [PATCH v2 4/4] mm: page_owner: use new iteration API

>> To be precise, can't we simply do the following on top?
> 
> Yes, that looks good and I like how the new API allows for simpler code.
> 
> My only concern is that if the user is not familiar with the page_ext
> internals, it might not be clear what page_ext_put() is actually
> protecting in which case it looks wrong that we're using a reference
> returned by get_page_owner() after releasing the lock. If you think
> that that's not an issue then I can apply this change on top.

The page_ext stuff only protects the page_ext itself, not any data 
stored in there. So I assume this should be just fine.

(most of these cases shouldn't need any protection, because the page_ext 
should not actually ever vanish here for memory that we are holding in 
our hands; but we decided to just add it everywhere for consistency)

-- 
Cheers,

David / dhildenb