+ mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures.patch added to mm-new branch

+ mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures.patch added to mm-new branch

[Andrew Morton]

The patch titled
     Subject: mm: enable MMU_GATHER_RCU_TABLE_FREE for most 2-level architectures
has been added to the -mm mm-new branch.  Its filename is
     mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures.patch

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

Note, mm-new is a provisional staging ground for work-in-progress
patches, and acceptance into mm-new is a notification for others take
notice and to finish up reviews.  Please do not hesitate to respond to
review feedback and post updated versions to replace or incrementally
fixup patches in mm-new.

The mm-new branch of mm.git is not included in linux-next

If a few days of testing in mm-new is successful, the patch will me moved
into mm.git's mm-unstable branch, which is included in linux-next

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   a) Consider who else should be cc'ed
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*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***

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and is updated there most days

------------------------------------------------------
From: "Lorenzo Stoakes (ARM)" <ljs@kernel.org>
Subject: mm: enable MMU_GATHER_RCU_TABLE_FREE for most 2-level architectures
Date: Tue, 08 Sep 2026 13:32:11 +0100

Commit e3ecf7c7d082 ("mm: pgtable: convert some architectures to use
tlb_remove_ptdesc()") updated a number of architectures from using
pagetable_dtor() + tlb_remove_page_ptdesc() to using tlb_remove_ptdesc()
in __pte_free_tlb().

This is meaningful as tlb_remove_ptdesc() allows for RCU page table
freeing if CONFIG_MMU_GATHER_RCU_TABLE_FREE is specified.

The csky, hexagon, nios2, openrisc, sh (except X2) and m68k-sun3
architectures all have 2 levels of page tables, so the only page tables
ever freed by mmu_gather are PTEs, so this update suffices to ensure that
every page table freed by the mmu_gather mechanism is freed under RCU.

Therefore, update all of these architectures to select
CONFIG_MMU_GATHER_RCU_TABLE_FREE.

This forms part of an overall effort to switch every architecture to this
mode.

Link: https://lore.kernel.org/20260908-rcu-pagetable-freeing-v2-2-1f60b64e878e@kernel.org
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: "Borislav Petkov (AMD)" <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christian Zankel <chris@zankel.net>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Bottomley <james.bottomley@HansenPartnership.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Johannes Berg <johannes@sipsolutions.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Kiryl Shutsemau <kas@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Magnus Lindholm <linmag7@gmail.com>
Cc: Marc Rutland <mark.rutland@arm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Richard Henderson <richard.henderson@linaro.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: WANG Xuerui <kernel@xen0n.name>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/csky/Kconfig     |    1 +
 arch/hexagon/Kconfig  |    1 +
 arch/m68k/Kconfig     |    1 +
 arch/nios2/Kconfig    |    1 +
 arch/openrisc/Kconfig |    1 +
 arch/sh/Kconfig       |    1 +
 6 files changed, 6 insertions(+)

--- a/arch/csky/Kconfig~mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures
+++ a/arch/csky/Kconfig
@@ -96,6 +96,7 @@ config CSKY
 	select HAVE_SYSCALL_TRACEPOINTS
 	select HOTPLUG_CORE_SYNC_DEAD if HOTPLUG_CPU
 	select LOCK_MM_AND_FIND_VMA
+	select MMU_GATHER_RCU_TABLE_FREE
 	select MAY_HAVE_SPARSE_IRQ
 	select MODULES_USE_ELF_RELA if MODULES
 	select OF
--- a/arch/hexagon/Kconfig~mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures
+++ a/arch/hexagon/Kconfig
@@ -23,6 +23,7 @@ config HEXAGON
 	# select HAVE_CLK
 	select GENERIC_ATOMIC64
 	select HAVE_PERF_EVENTS
+	select MMU_GATHER_RCU_TABLE_FREE
 	# GENERIC_ALLOCATOR is used by dma_alloc_coherent()
 	select GENERIC_ALLOCATOR
 	select GENERIC_IRQ_PROBE
--- a/arch/m68k/Kconfig~mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures
+++ a/arch/m68k/Kconfig
@@ -36,6 +36,7 @@ config M68K
 	select HAVE_MOD_ARCH_SPECIFIC
 	select HAVE_UID16
 	select MMU_GATHER_NO_RANGE if MMU
+	select MMU_GATHER_RCU_TABLE_FREE if MMU && SUN3
 	select MODULES_USE_ELF_REL
 	select MODULES_USE_ELF_RELA
 	select NO_DMA if !MMU && !COLDFIRE
--- a/arch/nios2/Kconfig~mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures
+++ a/arch/nios2/Kconfig
@@ -19,6 +19,7 @@ config NIOS2
 	select HAVE_PAGE_SIZE_4KB
 	select IRQ_DOMAIN
 	select LOCK_MM_AND_FIND_VMA
+	select MMU_GATHER_RCU_TABLE_FREE
 	select MODULES_USE_ELF_RELA
 	select OF
 	select OF_EARLY_FLATTREE
--- a/arch/openrisc/Kconfig~mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures
+++ a/arch/openrisc/Kconfig
@@ -35,6 +35,7 @@ config OPENRISC
 	select GENERIC_ATOMIC64
 	select GENERIC_CLOCKEVENTS_BROADCAST
 	select GENERIC_SMP_IDLE_THREAD
+	select MMU_GATHER_RCU_TABLE_FREE
 	select MODULES_USE_ELF_RELA
 	select HAVE_DEBUG_STACKOVERFLOW
 	select OR1K_PIC
--- a/arch/sh/Kconfig~mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures
+++ a/arch/sh/Kconfig
@@ -61,6 +61,7 @@ config SUPERH
 	select HAVE_SYSCALL_TRACEPOINTS
 	select IRQ_FORCED_THREADING
 	select LOCK_MM_AND_FIND_VMA
+	select MMU_GATHER_RCU_TABLE_FREE if MMU && !X2TLB
 	select MODULES_USE_ELF_RELA
 	select NEED_SG_DMA_LENGTH
 	select NO_DMA if !MMU && !DMA_COHERENT
_

Patches currently in -mm which might be from ljs@kernel.org are

mm-vma-correctly-unaccount-on-mmap_prepare-failure.patch
mm-vmpressure-remove-window-size-todo.patch
tools-testing-selftests-mm-add-missing-gitignore-entries.patch
mm-move-drivers-char-memc-to-mm-char-memc.patch
mm-implement-file_is_dev_zero-to-uniquely-identify-dev-zero.patch
mm-vma-only-permit-map_private-dev-zero-to-be-mapped-anonymous.patch
mm-vma-make-map_private-mapped-dev-zero-mappings-truly-anonymous.patch
tools-testing-vma-add-test-to-assert-map_private-dev-zero-is-anon.patch
tools-testing-selftests-mm-add-map_private-dev-zero-merge-tests.patch
mm-madvise-swap-in-cowd-map_private-file-mappings-on-madv_willneed.patch
mm-huge_memory-zap-deposited-page-tables-after-an-rcu-grace-period.patch
mm-enable-mmu_gather_rcu_table_free-for-most-2-level-architectures.patch
mm-enable-mmu_gather_rcu_table_free-for-mmu-riscv.patch
mm-enable-mmu_gather_rcu_table_free-for-mmu-arm.patch
mm-enable-mmu_gather_rcu_table_free-for-arc-microblaze-xtensa.patch
mm-enable-mmu_gather_rcu_table_free-for-sparc64.patch
mm-enable-mmu_gather_rcu_table_free-for-m68k-coldfire.patch
mm-enable-mmu_gather_rcu_table_free-for-sh-x2.patch
mm-enable-mmu_gather_rcu_table_free-for-m68k-motorola.patch
mm-enable-mmu_gather_rcu_table_free-for-sparc32.patch
mm-make-userland-page-table-freeing-rcu-safe.patch
mm-change-the-contract-for-free_pgtables-update-docs.patch