linux-kernel - Re: [PATCH v2 06/14] arm64/mm: Hoist barriers out of set_ptes

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Message-ID: <Z7m7e1W8LpYvV_h0@arm.com>
Date: Sat, 22 Feb 2025 11:56:43 +0000
From: Catalin Marinas <catalin.marinas@....com>
To: Ryan Roberts <ryan.roberts@....com>
Cc: Will Deacon <will@...nel.org>,
	Pasha Tatashin <pasha.tatashin@...een.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Uladzislau Rezki <urezki@...il.com>,
	Christoph Hellwig <hch@...radead.org>,
	David Hildenbrand <david@...hat.com>,
	"Matthew Wilcox (Oracle)" <willy@...radead.org>,
	Mark Rutland <mark.rutland@....com>,
	Anshuman Khandual <anshuman.khandual@....com>,
	Alexandre Ghiti <alexghiti@...osinc.com>,
	Kevin Brodsky <kevin.brodsky@....com>,
	linux-arm-kernel@...ts.infradead.org, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 06/14] arm64/mm: Hoist barriers out of
 set_ptes_anysz() loop

On Mon, Feb 17, 2025 at 02:07:58PM +0000, Ryan Roberts wrote:
> diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h
> index e255a36380dc..e4b1946b261f 100644
> --- a/arch/arm64/include/asm/pgtable.h
> +++ b/arch/arm64/include/asm/pgtable.h
> @@ -317,10 +317,8 @@ static inline void __set_pte_nosync(pte_t *ptep, pte_t pte)
>  	WRITE_ONCE(*ptep, pte);
>  }
>  
> -static inline void __set_pte(pte_t *ptep, pte_t pte)
> +static inline void __set_pte_complete(pte_t pte)
>  {
> -	__set_pte_nosync(ptep, pte);
> -
>  	/*
>  	 * Only if the new pte is valid and kernel, otherwise TLB maintenance
>  	 * or update_mmu_cache() have the necessary barriers.

Unrelated to this patch but I just realised that this comment is stale,
we no longer do anything in update_mmu_cache() since commit 120798d2e7d1
("arm64: mm: remove dsb from update_mmu_cache"). If you respin, please
remove the update_mmu_cache() part as well.

Thanks.

-- 
Catalin