linux-kernel - Re: [PATCH v4] mm: Avoid unnecessary page fault retires on shared memory types

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Date:   Mon, 30 May 2022 14:31:52 +0100
From:   Catalin Marinas <catalin.marinas@....com>
To:     Peter Xu <peterx@...hat.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Will Deacon <will@...nel.org>,
        Matt Turner <mattst88@...il.com>, linux-s390@...r.kernel.org,
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        Dave Hansen <dave.hansen@...ux.intel.com>,
        Richard Weinberger <richard@....at>,
        Ingo Molnar <mingo@...nel.org>
Subject: Re: [PATCH v4] mm: Avoid unnecessary page fault retires on shared
 memory types

On Fri, May 27, 2022 at 03:39:36PM -0400, Peter Xu wrote:
> diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c
> index 77341b160aca..e401d416bbd6 100644
> --- a/arch/arm64/mm/fault.c
> +++ b/arch/arm64/mm/fault.c
> @@ -607,6 +607,10 @@ static int __kprobes do_page_fault(unsigned long far, unsigned int esr,
>  		return 0;
>  	}
>  
> +	/* The fault is fully completed (including releasing mmap lock) */
> +	if (fault & VM_FAULT_COMPLETED)
> +		return 0;
> +
>  	if (fault & VM_FAULT_RETRY) {
>  		mm_flags |= FAULT_FLAG_TRIED;
>  		goto retry;

For arm64:

Acked-by: Catalin Marinas <catalin.marinas@....com>