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[v5,06/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for sparc64

Message ID 20260925-rcu-pagetable-freeing-v5-6-31e91065fea4@kernel.org
State New
Headers show
Series mm: make userland page table freeing RCU-safe | expand

Commit Message

Lorenzo Stoakes (ARM) Sept. 25, 2026, 8:09 p.m. UTC 
Commit 4a0100f7546f ("sparc64: use RCU page table freeing") enabled
CONFIG_MMU_GATHER_RCU_TABLE_FREE for SMP sparc64 architectures, expressly
for GUP-fast page table walkers.

Naturally, UP systems do not have to worry about concurrent GUP fast
operations.

However, CONFIG_PREEMPT_RCU is also available even on a UP system, so a
future pure-RCU page table walker requires MMU_GATHER_RCU_TABLE_FREE to be
enabled on UP, even if concurrent GUP fast is not possible there.

To enable future pure-RCU page table walkers, enable
MMU_GATHER_RCU_TABLE_FREE unconditionally.

With this change, it is no longer necessary to have !CONFIG_SMP
pgtable_free_tlb(), so also remove this now dead code.

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

Acked-by: Kiryl Shutsemau (Meta) <kas@kernel.org>
Tested-by: Lance Yang <lance.yang@linux.dev>
Acked-by: Lance Yang <lance.yang@linux.dev>
Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>
---
 arch/sparc/Kconfig                  | 4 ++--
 arch/sparc/include/asm/pgalloc_64.h | 8 --------
 2 files changed, 2 insertions(+), 10 deletions(-)
diff mbox series

Patch

diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
index ab77d3f2536e..8d42ebc6d302 100644
--- a/arch/sparc/Kconfig
+++ b/arch/sparc/Kconfig
@@ -75,8 +75,8 @@  config SPARC64
 	select HAVE_FUNCTION_GRAPH_TRACER
 	select HAVE_KRETPROBES
 	select HAVE_KPROBES
-	select MMU_GATHER_RCU_TABLE_FREE if SMP
-	select HAVE_ARCH_TLB_REMOVE_TABLE if SMP
+	select MMU_GATHER_RCU_TABLE_FREE
+	select HAVE_ARCH_TLB_REMOVE_TABLE
 	select MMU_GATHER_MERGE_VMAS
 	select MMU_GATHER_NO_FLUSH_CACHE
 	select HAVE_ARCH_TRANSPARENT_HUGEPAGE
diff --git a/arch/sparc/include/asm/pgalloc_64.h b/arch/sparc/include/asm/pgalloc_64.h
index caa7632be4c2..b5055d259b74 100644
--- a/arch/sparc/include/asm/pgalloc_64.h
+++ b/arch/sparc/include/asm/pgalloc_64.h
@@ -74,8 +74,6 @@  void pte_free_defer(struct mm_struct *mm, pgtable_t pgtable);
 
 void pgtable_free(void *table, bool is_page);
 
-#ifdef CONFIG_SMP
-
 struct mmu_gather;
 void tlb_remove_table(struct mmu_gather *, void *);
 
@@ -96,12 +94,6 @@  static inline void __tlb_remove_table(void *_table)
 		is_page = true;
 	pgtable_free(table, is_page);
 }
-#else /* CONFIG_SMP */
-static inline void pgtable_free_tlb(struct mmu_gather *tlb, void *table, bool is_page)
-{
-	pgtable_free(table, is_page);
-}
-#endif /* !CONFIG_SMP */
 
 static inline void __pte_free_tlb(struct mmu_gather *tlb, pte_t *pte,
 				  unsigned long address)