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

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Message-ID: <aPvOfIfcRM0X_RaK@gourry-fedora-PF4VCD3F>
Date: Fri, 24 Oct 2025 15:07:40 -0400
From: Gregory Price <gourry@...rry.net>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	Christian Borntraeger <borntraeger@...ux.ibm.com>,
	Janosch Frank <frankja@...ux.ibm.com>,
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	Sven Schnelle <svens@...ux.ibm.com>, Zi Yan <ziy@...dia.com>,
	Baolin Wang <baolin.wang@...ux.alibaba.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 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.

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

--- 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.

---

~Gregory