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[02/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for most 2-level architectures

Message ID 20260901-rcu-pagetable-freeing-v1-2-5456a81c8212@kernel.org
State New
Headers show
Series mm: make userland page table freeing RCU-safe | expand

Commit Message

Lorenzo Stoakes (ARM) Sept. 1, 2026, 11:01 a.m. UTC 
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.

Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.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(+)
diff mbox series

Patch

diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
index 4331313a42ff..80f89ef1d962 100644
--- a/arch/csky/Kconfig
+++ b/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
diff --git a/arch/hexagon/Kconfig b/arch/hexagon/Kconfig
index b48491140013..d9b3fb86556b 100644
--- a/arch/hexagon/Kconfig
+++ b/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
diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
index 11835eb59d94..e29610fd1240 100644
--- a/arch/m68k/Kconfig
+++ b/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
diff --git a/arch/nios2/Kconfig b/arch/nios2/Kconfig
index 9c0e6eaeb005..b0ccfc3b7a7e 100644
--- a/arch/nios2/Kconfig
+++ b/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
diff --git a/arch/openrisc/Kconfig b/arch/openrisc/Kconfig
index 5eb995c13074..d90b24dd3bce 100644
--- a/arch/openrisc/Kconfig
+++ b/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
diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
index d60f1d5a94c0..204f64912f0e 100644
--- a/arch/sh/Kconfig
+++ b/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