From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: stable@vger.kernel.org
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	patches@lists.linux.dev,
	"Vishal Moola (Oracle)" <vishal.moola@gmail.com>,
	Dave Hansen <dave.hansen@linux.intel.com>,
	"Mike Rapoport (Microsoft)" <rppt@kernel.org>,
	Sasha Levin <sashal@kernel.org>
Subject: [PATCH 6.18 1192/1250] x86/mm/pat: Convert split_large_page() to use ptdescs
Date: Thu, 17 Sep 2026 16:16:27 +0100
Message-ID: <20260917151624.593005259@linuxfoundation.org>
In-Reply-To: <20260917151551.901433442@linuxfoundation.org>
References: <20260917151551.901433442@linuxfoundation.org>
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6.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: "Vishal Moola (Oracle)" <vishal.moola@gmail.com>

[ Upstream commit e751303e0ad2e998f421d104193f6904df3516d1 ]

Use the ptdesc APIs for all page table allocation and free sites to
allow their separate allocation from struct page in the future.

Update split_large_page() to allocate a ptdesc instead of allocating a
page for use as a page table.

Signed-off-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Link: https://patch.msgid.link/20260303194828.1406905-5-vishal.moola@gmail.com
Stable-dep-of: 9e4a3ec3411b ("x86/mm/pat: Allocate split page tables as kernel page tables")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/x86/mm/pat/set_memory.c |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

--- a/arch/x86/mm/pat/set_memory.c
+++ b/arch/x86/mm/pat/set_memory.c
@@ -1138,9 +1138,10 @@ set:
 
 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);
 	unsigned int i, level;
 	pgprot_t ref_prot;
@@ -1245,18 +1246,18 @@ __split_large_page(struct cpa_data *cpa,
 static int split_large_page(struct cpa_data *cpa, pte_t *kpte,
 			    unsigned long address)
 {
-	struct page *base;
+	struct ptdesc *ptdesc;
 
 	if (!debug_pagealloc_enabled())
 		spin_unlock(&cpa_lock);
-	base = alloc_pages(GFP_KERNEL, 0);
+	ptdesc = pagetable_alloc(GFP_KERNEL, 0);
 	if (!debug_pagealloc_enabled())
 		spin_lock(&cpa_lock);
-	if (!base)
+	if (!ptdesc)
 		return -ENOMEM;
 
-	if (__split_large_page(cpa, kpte, address, base))
-		__free_page(base);
+	if (__split_large_page(cpa, kpte, address, ptdesc))
+		pagetable_free(ptdesc);
 
 	return 0;
 }