linux-kernel - [PATCH v4 4/8] mm: Introduce pure page table freeing function

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Message-ID: <20250905055103.3821518-5-baolu.lu@linux.intel.com>
Date: Fri,  5 Sep 2025 13:50:59 +0800
From: Lu Baolu <baolu.lu@...ux.intel.com>
To: Joerg Roedel <joro@...tes.org>,
	Will Deacon <will@...nel.org>,
	Robin Murphy <robin.murphy@....com>,
	Kevin Tian <kevin.tian@...el.com>,
	Jason Gunthorpe <jgg@...dia.com>,
	Jann Horn <jannh@...gle.com>,
	Vasant Hegde <vasant.hegde@....com>,
	Dave Hansen <dave.hansen@...el.com>,
	Alistair Popple <apopple@...dia.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Uladzislau Rezki <urezki@...il.com>,
	Jean-Philippe Brucker <jean-philippe@...aro.org>,
	Andy Lutomirski <luto@...nel.org>,
	Yi Lai <yi1.lai@...el.com>
Cc: iommu@...ts.linux.dev,
	security@...nel.org,
	linux-kernel@...r.kernel.org,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Lu Baolu <baolu.lu@...ux.intel.com>
Subject: [PATCH v4 4/8] mm: Introduce pure page table freeing function

From: Dave Hansen <dave.hansen@...ux.intel.com>

The pages used for ptdescs are currently freed back to the allocator
in a single location. They will shortly be freed from a second
location.

Create a simple helper that just frees them back to the allocator.

Signed-off-by: Dave Hansen <dave.hansen@...ux.intel.com>
Signed-off-by: Lu Baolu <baolu.lu@...ux.intel.com>
---
 include/linux/mm.h | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index f3db3a5ebefe..668d519edc0f 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2884,6 +2884,13 @@ static inline struct ptdesc *pagetable_alloc_noprof(gfp_t gfp, unsigned int orde
 }
 #define pagetable_alloc(...)	alloc_hooks(pagetable_alloc_noprof(__VA_ARGS__))
 
+static inline void __pagetable_free(struct ptdesc *pt)
+{
+	struct page *page = ptdesc_page(pt);
+
+	__free_pages(page, compound_order(page));
+}
+
 /**
  * pagetable_free - Free pagetables
  * @pt:	The page table descriptor
@@ -2893,12 +2900,10 @@ static inline struct ptdesc *pagetable_alloc_noprof(gfp_t gfp, unsigned int orde
  */
 static inline void pagetable_free(struct ptdesc *pt)
 {
-	struct page *page = ptdesc_page(pt);
-
 	if (ptdesc_test_kernel(pt))
 		ptdesc_clear_kernel(pt);
 
-	__free_pages(page, compound_order(page));
+	__pagetable_free(pt);
 }
 
 #if defined(CONFIG_SPLIT_PTE_PTLOCKS)
-- 
2.43.0