linux-kernel - [PATCH v6 10/14] arm64: mm: replace TIF_LAZY_MMU with is_lazy_mmu_mode

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Message-ID: <20251215150323.2218608-11-kevin.brodsky@arm.com>
Date: Mon, 15 Dec 2025 15:03:19 +0000
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>,
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	"David Hildenbrand (Red Hat)" <david@...nel.org>
Subject: [PATCH v6 10/14] arm64: mm: replace TIF_LAZY_MMU with is_lazy_mmu_mode_active()

The generic lazy_mmu layer now tracks whether a task is in lazy MMU
mode. As a result we no longer need a TIF flag for that purpose -
let's use the new is_lazy_mmu_mode_active() helper instead.

The explicit check for in_interrupt() is no longer necessary either
as is_lazy_mmu_mode_active() always returns false in interrupt
context.

Acked-by: David Hildenbrand (Red Hat) <david@...nel.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@....com>
Signed-off-by: Kevin Brodsky <kevin.brodsky@....com>
---
 arch/arm64/include/asm/pgtable.h     | 19 +++----------------
 arch/arm64/include/asm/thread_info.h |  3 +--
 2 files changed, 4 insertions(+), 18 deletions(-)

diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
index 7f528c36d53c..445e18e92221 100644
--- a/arch/arm64/include/asm/pgtable.h
+++ b/arch/arm64/include/asm/pgtable.h
@@ -62,28 +62,16 @@ static inline void emit_pte_barriers(void)
 
 static inline void queue_pte_barriers(void)
 {
-	unsigned long flags;
-
-	if (in_interrupt()) {
-		emit_pte_barriers();
-		return;
-	}
-
-	flags = read_thread_flags();
-
-	if (flags & BIT(TIF_LAZY_MMU)) {
+	if (is_lazy_mmu_mode_active()) {
 		/* Avoid the atomic op if already set. */
-		if (!(flags & BIT(TIF_LAZY_MMU_PENDING)))
+		if (!test_thread_flag(TIF_LAZY_MMU_PENDING))
 			set_thread_flag(TIF_LAZY_MMU_PENDING);
 	} else {
 		emit_pte_barriers();
 	}
 }
 
-static inline void arch_enter_lazy_mmu_mode(void)
-{
-	set_thread_flag(TIF_LAZY_MMU);
-}
+static inline void arch_enter_lazy_mmu_mode(void) {}
 
 static inline void arch_flush_lazy_mmu_mode(void)
 {
@@ -94,7 +82,6 @@ static inline void arch_flush_lazy_mmu_mode(void)
 static inline void arch_leave_lazy_mmu_mode(void)
 {
 	arch_flush_lazy_mmu_mode();
-	clear_thread_flag(TIF_LAZY_MMU);
 }
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
diff --git a/arch/arm64/include/asm/thread_info.h b/arch/arm64/include/asm/thread_info.h
index a803b887b0b4..e7cd017b07c8 100644
--- a/arch/arm64/include/asm/thread_info.h
+++ b/arch/arm64/include/asm/thread_info.h
@@ -84,8 +84,7 @@ void arch_setup_new_exec(void);
 #define TIF_SME_VL_INHERIT	28	/* Inherit SME vl_onexec across exec */
 #define TIF_KERNEL_FPSTATE	29	/* Task is in a kernel mode FPSIMD section */
 #define TIF_TSC_SIGSEGV		30	/* SIGSEGV on counter-timer access */
-#define TIF_LAZY_MMU		31	/* Task in lazy mmu mode */
-#define TIF_LAZY_MMU_PENDING	32	/* Ops pending for lazy mmu mode exit */
+#define TIF_LAZY_MMU_PENDING	31	/* Ops pending for lazy mmu mode exit */
 
 #define _TIF_SIGPENDING		(1 << TIF_SIGPENDING)
 #define _TIF_NEED_RESCHED	(1 << TIF_NEED_RESCHED)
-- 
2.51.2