[PATCH v5 3/4] x86/mm/pat: Convert pmd code to use ptdescs

From: Vishal Moola (Oracle)

Date: Wed Feb 11 2026 - 14:53:51 EST


We need all allocation and free sites to use the ptdesc APIs in order to
allocate them separately from regular pages. Convert these pmd
allocation/free sites to use ptdescs.

Allocate ptdescs in popoulate_pgd() as well since those allocations may
later be freed by try_to_free_pmd_page().

Also, rename *_pmd_page() functions to *_pmd(). Rename them now to avoid
any confusion later. Eventually these allocations will be backed by a
ptdesc not a page, but that's not important to callers either.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@xxxxxxxxx>
---
arch/x86/mm/pat/set_memory.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)

diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index 04eae65aedfc..9d6681443e54 100644
--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c
@@ -1412,7 +1412,7 @@ static bool try_to_free_pte(pte_t *pte)
return true;
}

-static bool try_to_free_pmd_page(pmd_t *pmd)
+static bool try_to_free_pmd(pmd_t *pmd)
{
int i;

@@ -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);
+ pgtable_free_addr(pmd);
return true;
}

@@ -1446,7 +1446,7 @@ static void __unmap_pmd_range(pud_t *pud, pmd_t *pmd,
unsigned long start, unsigned long end)
{
if (unmap_pte_range(pmd, start, end))
- if (try_to_free_pmd_page(pud_pgtable(*pud)))
+ if (try_to_free_pmd(pud_pgtable(*pud)))
pud_clear(pud);
}

@@ -1490,7 +1490,7 @@ static void unmap_pmd_range(pud_t *pud, unsigned long start, unsigned long end)
* Try again to free the PMD page if haven't succeeded above.
*/
if (!pud_none(*pud))
- if (try_to_free_pmd_page(pud_pgtable(*pud)))
+ if (try_to_free_pmd(pud_pgtable(*pud)))
pud_clear(pud);
}

@@ -1547,9 +1547,9 @@ static int alloc_pte(pmd_t *pmd)
return 0;
}

-static int alloc_pmd_page(pud_t *pud)
+static int alloc_pmd(pud_t *pud)
{
- pmd_t *pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
+ pmd_t *pmd = pgtable_alloc_addr(GFP_KERNEL, 0);
if (!pmd)
return -1;

@@ -1622,7 +1622,7 @@ 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(pud))
return -1;

pmd = pmd_offset(pud, start);
@@ -1678,7 +1678,7 @@ 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(pud))
return -1;

cur_pages = populate_pmd(cpa, start, pre_end, cur_pages,
@@ -1715,7 +1715,7 @@ 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(pud))
return -1;

tmp = populate_pmd(cpa, start, end, cpa->numpages - cur_pages,
@@ -1743,7 +1743,7 @@ static int populate_pgd(struct cpa_data *cpa, unsigned long addr)
pgd_entry = cpa->pgd + pgd_index(addr);

if (pgd_none(*pgd_entry)) {
- p4d = (p4d_t *)get_zeroed_page(GFP_KERNEL);
+ p4d = pgtable_alloc_addr(GFP_KERNEL, 0);
if (!p4d)
return -1;

@@ -1755,7 +1755,7 @@ static int populate_pgd(struct cpa_data *cpa, unsigned long addr)
*/
p4d = p4d_offset(pgd_entry, addr);
if (p4d_none(*p4d)) {
- pud = (pud_t *)get_zeroed_page(GFP_KERNEL);
+ pud = pgtable_alloc_addr(GFP_KERNEL, 0);
if (!pud)
return -1;

--
2.52.0