Subject: Re: [PATCH v9 28/44] arm64: mte: Reset the page tag in page->flags

From: Catalin Marinas <[email-masked]>
Date: Thu, 12 Nov 2020 09:31:31 +0000

On Tue, Nov 10, 2020 at 11:10:25PM +0100, Andrey Konovalov wrote:
> diff --git a/arch/arm64/mm/copypage.c b/arch/arm64/mm/copypage.c
> index 70a71f38b6a9..f0efa4847e2f 100644
> --- a/arch/arm64/mm/copypage.c
> +++ b/arch/arm64/mm/copypage.c
> @@ -23,6 +23,7 @@ void copy_highpage(struct page *to, struct page *from)
>  
>  	if (system_supports_mte() && test_bit(PG_mte_tagged, &from->flags)) {
>  		set_bit(PG_mte_tagged, &to->flags);
> +		page_kasan_tag_reset(to);
>  		mte_copy_page_tags(kto, kfrom);

Any reason why this doesn't have an smp_wmb() between resetting the tags
and copying them into kto?

-- 
Catalin

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