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Date: Sat, 8 Nov 2025 10:01:04 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
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Subject: Re: [PATCH v2 00/16] mm: remove is_swap_[pte, pmd]() + non-swap
 entries, introduce leaf entries
Message-Id: <20251108100104.bb9fc75f97b9263af7e5673b@linux-foundation.org>
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On Sat,  8 Nov 2025 17:08:14 +0000 Lorenzo Stoakes <lorenzo.stoakes@oracle.com> wrote:

> There's an established convention in the kernel that we treat leaf page
> tables (so far at the PTE, PMD level) as containing 'swap entries' should
> they be neither empty (i.e. p**_none() evaluating true) nor present
> (i.e. p**_present() evaluating true).
> 
> However, at the same time we also have helper predicates - is_swap_pte(),
> is_swap_pmd() - which are inconsistently used.
> 
> This is problematic, as it is logical to assume that should somebody wish
> to operate upon a page table swap entry they should first check to see if
> it is in fact one.
> 
> It also implies that perhaps, in future, we might introduce a non-present,
> none page table entry that is not a swap entry.
> 
> This series resolves this issue by systematically eliminating all use of
> the is_swap_pte() and is swap_pmd() predicates so we retain only the
> convention that should a leaf page table entry be neither none nor present
> it is a swap entry.

Thanks, I've updated mm.git's mm-unstable branch to this v2 series.