[RESEND PATCH v7 2/4] x86/mm/pat: Convert pmd code to use page table apis

["Vishal Moola (Oracle)" <vishal.moola@gmail.com>]

Use the ptdesc APIs for all page table allocation and free sites to allow
their separate allocation from struct page in the future. Convert the PMD
allocation and free sites to use the generic page table APIs, as they
already use ptdescs.

Pass through init_mm since these are kernel page tables, as
pmd_alloc_one() requires it to identify kernel page tables. Because the
generic implementation does not use the second argument, pass a
placeholder to avoid reimplementing it or risking breakage on other
architectures.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
---
 arch/x86/mm/pat/set_memory.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c
index a4b1b329c23d..72a260007996 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);
+	pmd_free(&init_mm, pmd);
 	return true;
 }
 
@@ -1549,7 +1549,11 @@ static int alloc_pte_page(pmd_t *pmd)
 
 static int alloc_pmd_page(pud_t *pud)
 {
-	pmd_t *pmd = (pmd_t *)get_zeroed_page(GFP_KERNEL);
+	/*
+	 * Pass 0 as a placeholder for the second argument, since the
+	 * generic implementation of pmd_alloc_one() does not use it.
+	 */
+	pmd_t *pmd = pmd_alloc_one(&init_mm, 0);
 	if (!pmd)
 		return -1;
 
-- 
2.53.0