[PATCH 2/3] x86/mm/pat: Convert pmd code to use ptdescs

From: Vishal Moola (Oracle)

Date: Mon Jan 26 2026 - 19:52:24 EST


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

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@xxxxxxxxx>
---
arch/x86/mm/pat/set_memory.c | 13 +++++++------
1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index 2dcb565d8f9b..ded1ba11c68f 100644
--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c
@@ -1420,7 +1420,7 @@ static bool try_to_free_pmd_page(pmd_t *pmd)
if (!pmd_none(pmd[i]))
return false;

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

@@ -1548,9 +1548,10 @@ static int alloc_pte_ptdesc(pmd_t *pmd)
return 0;
}

-static int alloc_pmd_page(pud_t *pud)
+static int alloc_pmd_ptdesc(pud_t *pud)
{
- pmd_t *pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
+ pmd_t *pmd = (pmd_t *) ptdesc_address(
+ pagetable_alloc(GFP_KERNEL | __GFP_ZERO, 0));
if (!pmd)
return -1;

@@ -1623,7 +1624,7 @@ static long populate_pmd(struct cpa_data *cpa,
* We cannot use a 1G page so allocate a PMD page if needed.
*/
if (pud_none(*pud))
- if (alloc_pmd_page(pud))
+ if (alloc_pmd_ptdesc(pud))
return -1;

pmd = pmd_offset(pud, start);
@@ -1679,7 +1680,7 @@ static int populate_pud(struct cpa_data *cpa, unsigned long start, p4d_t *p4d,
* Need a PMD page?
*/
if (pud_none(*pud))
- if (alloc_pmd_page(pud))
+ if (alloc_pmd_ptdesc(pud))
return -1;

cur_pages = populate_pmd(cpa, start, pre_end, cur_pages,
@@ -1716,7 +1717,7 @@ static int populate_pud(struct cpa_data *cpa, unsigned long start, p4d_t *p4d,

pud = pud_offset(p4d, start);
if (pud_none(*pud))
- if (alloc_pmd_page(pud))
+ if (alloc_pmd_ptdesc(pud))
return -1;

tmp = populate_pmd(cpa, start, end, cpa->numpages - cur_pages,
--
2.52.0