[PATCH v3 1/3] x86/mm/pat: Convert pte code to use ptdescs

Vishal Moola (Oracle)
2026-02-02T17:20:21Z

In order to separately allocate ptdescs from pages, we need all allocation
and free sites to use the appropriate functions. Convert these pte
allocation/free sites to use ptdescs.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
---
arch/x86/mm/pat/set_memory.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index 6c6eb486f7a6..f9f9d4ca8e71 100644
--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c
@@ -1408,7 +1408,7 @@ static bool try_to_free_pte_page(pte_t *pte)
if (!pte_none(pte[i]))
return false;

- free_page((unsigned long)pte);
+ pagetable_free(virt_to_ptdesc((void *)pte));
return true;
}

@@ -1537,12 +1537,15 @@ static void unmap_pud_range(p4d_t *p4d, unsigned long start, unsigned long end)
*/
}

-static int alloc_pte_page(pmd_t *pmd)
+static int alloc_pte_ptdesc(pmd_t *pmd)
{
- pte_t *pte = (pte_t *)get_zeroed_page(GFP_KERNEL);
- if (!pte)
+ pte_t *pte;
+ struct ptdesc *ptdesc = pagetable_alloc(GFP_KERNEL | __GFP_ZERO, 0);
+
+ if (!ptdesc)
return -1;

+ pte = (pte_t *) ptdesc_address(ptdesc);
set_pmd(pmd, __pmd(__pa(pte) | _KERNPG_TABLE));
return 0;
}
@@ -1600,7 +1603,7 @@ static long populate_pmd(struct cpa_data *cpa,
*/
pmd = pmd_offset(pud, start);
if (pmd_none(*pmd))
- if (alloc_pte_page(pmd))
+ if (alloc_pte_ptdesc(pmd))
return -1;

populate_pte(cpa, start, pre_end, cur_pages, pmd, pgprot);
@@ -1641,7 +1644,7 @@ static long populate_pmd(struct cpa_data *cpa,
if (start < end) {
pmd = pmd_offset(pud, start);
if (pmd_none(*pmd))
- if (alloc_pte_page(pmd))
+ if (alloc_pte_ptdesc(pmd))
return -1;

populate_pte(cpa, start, end, num_pages - cur_pages,
--
2.52.0