linux-kernel - Re: [RFC PATCH 11/12] mm: rename non_swap_entry() to is_non_present

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Message-ID: <7caff42a-d471-4b4d-b7bf-61f74a75b9d0@lucifer.local>
Date: Fri, 24 Oct 2025 21:17:14 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Gregory Price <gourry@...rry.net>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        David Hildenbrand <david@...hat.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>, Zi Yan <ziy@...dia.com>,
        Baolin Wang <baolin.wang@...ux.alibaba.com>,
        "Liam R . Howlett" <Liam.Howlett@...cle.com>,
        Nico Pache <npache@...hat.com>, Ryan Roberts <ryan.roberts@....com>,
        Dev Jain <dev.jain@....com>, Barry Song <baohua@...nel.org>,
        Lance Yang <lance.yang@...ux.dev>,
        Kemeng Shi <shikemeng@...weicloud.com>,
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        Baoquan He <bhe@...hat.com>, Chris Li <chrisl@...nel.org>,
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        Muchun Song <muchun.song@...ux.dev>,
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        Mike Rapoport <rppt@...nel.org>,
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        Byungchul Park <byungchul@...com>,
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        Alistair Popple <apopple@...dia.com>, Pedro Falcato <pfalcato@...e.de>,
        Pasha Tatashin <pasha.tatashin@...een.com>,
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        kvm@...r.kernel.org, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org
Subject: Re: [RFC PATCH 11/12] mm: rename non_swap_entry() to
 is_non_present_entry()

On Fri, Oct 24, 2025 at 03:07:40PM -0400, Gregory Price wrote:
> On Fri, Oct 24, 2025 at 08:41:27AM +0100, Lorenzo Stoakes wrote:
> > Referring to non-swap swap entries is simply confusing. While we store
> > non-present entries unrelated to swap itself, in swp_entry_t fields, we can
> > avoid referring to them as 'non-swap' entries.
> >
> --- >8
> >  static void ptep_zap_swap_entry(struct mm_struct *mm, swp_entry_t entry)
> >  {
> > -	if (!non_swap_entry(entry))
> > +	if (!is_non_present_entry(entry))
> >  		dec_mm_counter(mm, MM_SWAPENTS);
>
> I guess the question I have here is whether it's feasible to invert the
> logic to avoid the double-negative not-logic.

Ah well, see the next patch :)

>
> Anyway, naming is hard. In general I appreciate the additional clarity,
> even if we still have some `!is_non_*` logic sprinkled about.

Again this is a prelude to 12/12 :P

>
> --- addt'l aside semi-unrelated to your patches
>
> I can see where this is going in the long run, but the name of this
> function (ptep_zap_swap_entry) is as frustrating as the check for
> non_swap_entry(entry).
>
> may as well call it `ptep_zap_leaf_thingy` if it's handling multiple
> special entry types.
>
> but renaming even more functions in strange places outside scope here.

Yeah there's more to do for sure, I'll add this to the list... :)

>
> ---
>
> ~Gregory

Cheers, Lorenzo