linux-kernel - [PATCH 1/7] mm: remove arch_flush_lazy_mmu

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Message-ID: <20250904125736.3918646-2-kevin.brodsky@arm.com>
Date: Thu,  4 Sep 2025 13:57:30 +0100
From: Kevin Brodsky <kevin.brodsky@....com>
To: linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org,
	Kevin Brodsky <kevin.brodsky@....com>,
	Alexander Gordeev <agordeev@...ux.ibm.com>,
	Andreas Larsson <andreas@...sler.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Boris Ostrovsky <boris.ostrovsky@...cle.com>,
	Borislav Petkov <bp@...en8.de>,
	Catalin Marinas <catalin.marinas@....com>,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	David Hildenbrand <david@...hat.com>,
	"David S. Miller" <davem@...emloft.net>,
	"H. Peter Anvin" <hpa@...or.com>,
	Ingo Molnar <mingo@...hat.com>,
	Jann Horn <jannh@...gle.com>,
	Juergen Gross <jgross@...e.com>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Madhavan Srinivasan <maddy@...ux.ibm.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Michal Hocko <mhocko@...e.com>,
	Mike Rapoport <rppt@...nel.org>,
	Nicholas Piggin <npiggin@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Ryan Roberts <ryan.roberts@....com>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Vlastimil Babka <vbabka@...e.cz>,
	Will Deacon <will@...nel.org>,
	linux-arm-kernel@...ts.infradead.org,
	linuxppc-dev@...ts.ozlabs.org,
	sparclinux@...r.kernel.org,
	xen-devel@...ts.xenproject.org
Subject: [PATCH 1/7] mm: remove arch_flush_lazy_mmu_mode()

This function has only ever been used in arch/x86, so there is no
need for other architectures to implement it. Remove it from
linux/pgtable.h and all architectures besides x86.

The arm64 implementation is not empty but it is only called from
arch_leave_lazy_mmu_mode(), so we can simply fold it there.

Signed-off-by: Kevin Brodsky <kevin.brodsky@....com>
---
 arch/arm64/include/asm/pgtable.h                   | 9 +--------
 arch/powerpc/include/asm/book3s/64/tlbflush-hash.h | 2 --
 arch/sparc/include/asm/tlbflush_64.h               | 1 -
 arch/x86/include/asm/pgtable.h                     | 3 ++-
 include/linux/pgtable.h                            | 1 -
 5 files changed, 3 insertions(+), 13 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index abd2dee416b3..728d7b6ed20a 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -101,21 +101,14 @@ static inline void arch_enter_lazy_mmu_mode(void)
 	set_thread_flag(TIF_LAZY_MMU);
 }
 
-static inline void arch_flush_lazy_mmu_mode(void)
+static inline void arch_leave_lazy_mmu_mode(void)
 {
 	if (in_interrupt())
 		return;
 
 	if (test_and_clear_thread_flag(TIF_LAZY_MMU_PENDING))
 		emit_pte_barriers();
-}
-
-static inline void arch_leave_lazy_mmu_mode(void)
-{
-	if (in_interrupt())
-		return;
 
-	arch_flush_lazy_mmu_mode();
 	clear_thread_flag(TIF_LAZY_MMU);
 }
 
diff --git a/arch/powerpc/include/asm/book3s/64/tlbflush-hash.h b/arch/powerpc/include/asm/book3s/64/tlbflush-hash.h
index 146287d9580f..176d7fd79eeb 100644
--- a/arch/powerpc/include/asm/book3s/64/tlbflush-hash.h
+++ b/arch/powerpc/include/asm/book3s/64/tlbflush-hash.h
@@ -55,8 +55,6 @@ static inline void arch_leave_lazy_mmu_mode(void)
 	preempt_enable();
 }
 
-#define arch_flush_lazy_mmu_mode()      do {} while (0)
-
 extern void hash__tlbiel_all(unsigned int action);
 
 extern void flush_hash_page(unsigned long vpn, real_pte_t pte, int psize,
diff --git a/arch/sparc/include/asm/tlbflush_64.h b/arch/sparc/include/asm/tlbflush_64.h
index 8b8cdaa69272..cd144eb31bdd 100644
--- a/arch/sparc/include/asm/tlbflush_64.h
+++ b/arch/sparc/include/asm/tlbflush_64.h
@@ -44,7 +44,6 @@ void flush_tlb_kernel_range(unsigned long start, unsigned long end);
 void flush_tlb_pending(void);
 void arch_enter_lazy_mmu_mode(void);
 void arch_leave_lazy_mmu_mode(void);
-#define arch_flush_lazy_mmu_mode()      do {} while (0)
 
 /* Local cpu only.  */
 void __flush_tlb_all(void);
diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index e33df3da6980..14fd672bc9b2 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -117,7 +117,8 @@ extern pmdval_t early_pmd_flags;
 #define pte_val(x)	native_pte_val(x)
 #define __pte(x)	native_make_pte(x)
 
-#define arch_end_context_switch(prev)	do {} while(0)
+#define arch_end_context_switch(prev)	do {} while (0)
+#define arch_flush_lazy_mmu_mode()	do {} while (0)
 #endif	/* CONFIG_PARAVIRT_XXL */
 
 static inline pmd_t pmd_set_flags(pmd_t pmd, pmdval_t set)
diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index 4c035637eeb7..8848e132a6be 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -234,7 +234,6 @@ static inline int pmd_dirty(pmd_t pmd)
 #ifndef __HAVE_ARCH_ENTER_LAZY_MMU_MODE
 #define arch_enter_lazy_mmu_mode()	do {} while (0)
 #define arch_leave_lazy_mmu_mode()	do {} while (0)
-#define arch_flush_lazy_mmu_mode()	do {} while (0)
 #endif
 
 #ifndef pte_batch_hint
-- 
2.47.0