Re: [PATCH v5 1/8] mm: Add a ptdesc flag to mark kernel page tables

[Matthew Wilcox]

On Fri, Sep 19, 2025 at 01:39:59PM +0800, Lu Baolu wrote:
> +static inline void ptdesc_set_kernel(struct ptdesc *ptdesc)
> +{
> +	struct folio *folio = ptdesc_folio(ptdesc);
> +
> +	folio_set_referenced(folio);
> +}

So this was the right way to do this at the time.  However, if you look
at commit 522abd92279a this should now be ...

 enum pt_flags {
 	PT_reserved = PG_reserved,
+	PT_kernel = PG_referenced,
 	/* High bits are used for zone/node/section */
 };
[...]

+static inline void ptdesc_set_kernel(struct ptdesc *ptdesc)
+{
+	set_bit(PT_kernel, &pt->pt_flags.f);
+}

(etc)