+ x86-pgtable-always-use-pte_free_kernel.patch added to mm-new branch

+ x86-pgtable-always-use-pte_free_kernel.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: x86: pgtable: always use pte_free_kernel()
has been added to the -mm mm-new branch.  Its filename is
     x86-pgtable-always-use-pte_free_kernel.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/x86-pgtable-always-use-pte_free_kernel.patch

This patch will later appear in the mm-new branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Kevin Brodsky <kevin.brodsky@arm.com>
Subject: x86: pgtable: always use pte_free_kernel()
Date: Tue, 8 Apr 2025 10:52:12 +0100

Page table pages are normally freed using the appropriate helper for the
given page table level.  On x86, pud_free_pmd_page() and
pmd_free_pte_page() are an exception to the rule: they call free_page()
directly.

Constructor/destructor calls are about to be introduced for kernel PTEs. 
To avoid missing dtor calls in those helpers, free the PTE pages using
pte_free_kernel() instead of free_page().

While at it also use pmd_free() instead of calling pagetable_dtor()
explicitly at the PMD level.

Link: https://lkml.kernel.org/r/20250408095222.860601-3-kevin.brodsky@arm.com
Signed-off-by: Kevin Brodsky <kevin.brodsky@arm.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Linus Waleij <linus.walleij@linaro.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcow (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: <x86@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/x86/mm/pgtable.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

--- a/arch/x86/mm/pgtable.c~x86-pgtable-always-use-pte_free_kernel
+++ a/arch/x86/mm/pgtable.c
@@ -809,14 +809,13 @@ int pud_free_pmd_page(pud_t *pud, unsign
 	for (i = 0; i < PTRS_PER_PMD; i++) {
 		if (!pmd_none(pmd_sv[i])) {
 			pte = (pte_t *)pmd_page_vaddr(pmd_sv[i]);
-			free_page((unsigned long)pte);
+			pte_free_kernel(&init_mm, pte);
 		}
 	}
 
 	free_page((unsigned long)pmd_sv);
 
-	pagetable_dtor(virt_to_ptdesc(pmd));
-	free_page((unsigned long)pmd);
+	pmd_free(&init_mm, pmd);
 
 	return 1;
 }
@@ -839,7 +838,7 @@ int pmd_free_pte_page(pmd_t *pmd, unsign
 	/* INVLPG to clear all paging-structure caches */
 	flush_tlb_kernel_range(addr, addr + PAGE_SIZE-1);
 
-	free_page((unsigned long)pte);
+	pte_free_kernel(&init_mm, pte);
 
 	return 1;
 }
_

Patches currently in -mm which might be from kevin.brodsky@arm.com are

mm-pass-mm-down-to-pagetable_ptepmd_ctor.patch
x86-pgtable-always-use-pte_free_kernel.patch
mm-call-ctor-dtor-for-kernel-ptes.patch
m68k-mm-call-ctor-dtor-for-kernel-ptes.patch
powerpc-mm-call-ctor-dtor-for-kernel-ptes.patch
sparc64-mm-call-ctor-dtor-for-kernel-ptes.patch
mm-skip-ptlock_init-for-kernel-pmds.patch
arm64-mm-use-enum-to-identify-pgtable-level-instead-of-_shift.patch
arm64-mm-always-call-pte-pmd-ctor-in-__create_pgd_mapping.patch
riscv-mm-clarify-ctor-mm-argument-in-alloc_ptepmd_late.patch
arm64-mm-call-pud-p4d-ctor-in-__create_pgd_mapping.patch
riscv-mm-call-pud-p4d-ctor-in-special-kernel-pgtable-alloc.patch