linux-kernel - Re: [PATCH v6 12/14] sparc/mm: replace batch->active with is_lazy_mmu_mode

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Message-ID: <544172e4-cdf7-4789-8cad-4dc3c498e497@gaisler.com>
Date: Wed, 14 Jan 2026 08:21:12 +0100
From: Andreas Larsson <andreas@...sler.com>
To: Kevin Brodsky <kevin.brodsky@....com>, linux-mm@...ck.org
Cc: linux-kernel@...r.kernel.org, Alexander Gordeev <agordeev@...ux.ibm.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Anshuman Khandual <anshuman.khandual@....com>,
 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>, David Woodhouse <dwmw2@...radead.org>,
 "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>,
 "Ritesh Harjani (IBM)" <ritesh.list@...il.com>,
 Ryan Roberts <ryan.roberts@....com>, Suren Baghdasaryan <surenb@...gle.com>,
 Thomas Gleixner <tglx@...utronix.de>,
 Venkat Rao Bagalkote <venkat88@...ux.ibm.com>,
 Vlastimil Babka <vbabka@...e.cz>, Will Deacon <will@...nel.org>,
 Yeoreum Yun <yeoreum.yun@....com>, linux-arm-kernel@...ts.infradead.org,
 linuxppc-dev@...ts.ozlabs.org, sparclinux@...r.kernel.org,
 xen-devel@...ts.xenproject.org, x86@...nel.org,
 "David Hildenbrand (Red Hat)" <david@...nel.org>
Subject: Re: [PATCH v6 12/14] sparc/mm: replace batch->active with
 is_lazy_mmu_mode_active()

On 2025-12-15 16:03, Kevin Brodsky wrote:
> A per-CPU batch struct is activated when entering lazy MMU mode; its
> lifetime is the same as the lazy MMU section (it is deactivated when
> leaving the mode). Preemption is disabled in that interval to ensure
> that the per-CPU reference remains valid.
> 
> The generic lazy_mmu layer now tracks whether a task is in lazy MMU
> mode. We can therefore use the generic helper
> is_lazy_mmu_mode_active() to tell whether a batch struct is active
> instead of tracking it explicitly.
> 
> Acked-by: David Hildenbrand (Red Hat) <david@...nel.org>
> Signed-off-by: Kevin Brodsky <kevin.brodsky@....com>
> ---
>  arch/sparc/include/asm/tlbflush_64.h | 1 -
>  arch/sparc/mm/tlb.c                  | 9 +--------
>  2 files changed, 1 insertion(+), 9 deletions(-)
> 
> diff --git a/arch/sparc/include/asm/tlbflush_64.h b/arch/sparc/include/asm/tlbflush_64.h
> index 4e1036728e2f..6133306ba59a 100644
> --- a/arch/sparc/include/asm/tlbflush_64.h
> +++ b/arch/sparc/include/asm/tlbflush_64.h
> @@ -12,7 +12,6 @@ struct tlb_batch {
>  	unsigned int hugepage_shift;
>  	struct mm_struct *mm;
>  	unsigned long tlb_nr;
> -	unsigned long active;
>  	unsigned long vaddrs[TLB_BATCH_NR];
>  };
>  
> diff --git a/arch/sparc/mm/tlb.c b/arch/sparc/mm/tlb.c
> index 7b5dfcdb1243..3a852071d260 100644
> --- a/arch/sparc/mm/tlb.c
> +++ b/arch/sparc/mm/tlb.c
> @@ -52,11 +52,7 @@ void flush_tlb_pending(void)
>  
>  void arch_enter_lazy_mmu_mode(void)
>  {
> -	struct tlb_batch *tb;
> -
>  	preempt_disable();
> -	tb = this_cpu_ptr(&tlb_batch);
> -	tb->active = 1;
>  }
>  
>  void arch_flush_lazy_mmu_mode(void)
> @@ -69,10 +65,7 @@ void arch_flush_lazy_mmu_mode(void)
>  
>  void arch_leave_lazy_mmu_mode(void)
>  {
> -	struct tlb_batch *tb = this_cpu_ptr(&tlb_batch);
> -
>  	arch_flush_lazy_mmu_mode();
> -	tb->active = 0;
>  	preempt_enable();
>  }
>  
> @@ -93,7 +86,7 @@ static void tlb_batch_add_one(struct mm_struct *mm, unsigned long vaddr,
>  		nr = 0;
>  	}
>  
> -	if (!tb->active) {
> +	if (!is_lazy_mmu_mode_active()) {
>  		flush_tsb_user_page(mm, vaddr, hugepage_shift);
>  		global_flush_tlb_page(mm, vaddr);
>  		goto out;

Acked-by: Andreas Larsson <andreas@...sler.com>

Cheers,
Andreas