[PATCH 02/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for most 2-level architectures
From: "Lorenzo Stoakes (ARM)" <ljs@kernel.org>
Date: 2026-09-01 11:05:42
Also in:
linux-alpha, linux-arch, linux-m68k, linux-mips, linux-mm, linux-riscv, linux-s390, linux-sh, linux-um, lkml, loongarch, sparclinux
Subsystem:
c-sky architecture, m68k architecture, nios2 architecture, openrisc architecture, qualcomm hexagon architecture, superh, the rest · Maintainers:
Guo Ren, Geert Uytterhoeven, Dinh Nguyen, Simon Schuster, Jonas Bonn, Stefan Kristiansson, Stafford Horne, Brian Cain, Yoshinori Sato, Rich Felker, John Paul Adrian Glaubitz, Linus Torvalds
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 --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
--
2.55.0