linux-kernel - Re: [PATCH v5 4/4] x86/mm/pat: Convert split_large

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Message-ID: <aY0E_EKc_yx_mPS7@fedora>
Date: Wed, 11 Feb 2026 14:38:52 -0800
From: "Vishal Moola (Oracle)" <vishal.moola@...il.com>
To: Matthew Wilcox <willy@...radead.org>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org,
	"Mike Rapoport (Microsoft)" <rppt@...nel.org>,
	akpm@...ux-foundation.org,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Andy Lutomirski <luto@...nel.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v5 4/4] x86/mm/pat: Convert split_large_page() to use
 ptdescs

On Wed, Feb 11, 2026 at 09:59:19PM +0000, Matthew Wilcox wrote:
> On Wed, Feb 11, 2026 at 11:52:33AM -0800, Vishal Moola (Oracle) wrote:
> >  static int
> >  __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address,
> > -		   struct page *base)
> > +		   struct ptdesc *ptdesc)
> >  {
> >  	unsigned long lpaddr, lpinc, ref_pfn, pfn, pfninc = 1;
> > +	struct page *base = ptdesc_page(ptdesc);
> >  	pte_t *pbase = (pte_t *)page_address(base);
> 
> We have ptdesc_address() already.  Can we avoid the other uses of
> 'base' in this function?

We could, but not without helpers similar to folio_pfn() and
folio_mk_pte(). I hadn't added those in this patchset since my primary
goal right now is to ensure all the allocation/free sites are using the
proper apis.