Re: [PATCH RFC 00/14] Remove PG_private by using page/folio->private checks instead

Jürgen Groß <[email protected]> Mon, 3 Aug 2026 11:07:39 +0200

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Message-ID	<[email protected]>

On 01.08.26 04:13, Zi Yan wrote:
> Hi all,
> 
> This patchset removes PG_private to make space for upcoming PG_folio
> (reserved as __PG_folio) for identifying pages from a folio (more details
> in Note below). Instead of checking PG_private, all code is changed to
> check page/folio->private != NULL instead.

I'm a little bit worried that page/folio->private is in a union, so today
it could (in theory) be != NULL while PG_private isn't set.

Is it really not possible to enter a path where PG_private is tested while
page/folio->private != NULL due to the union being used otherwise (PG_private
not set)?

Juergen

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