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Date:   Mon, 9 Sep 2019 14:27:12 -0700
From:   Matthew Wilcox <willy@infradead.org>
To:     Jia He <justin.he@arm.com>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        =?iso-8859-1?B?Suly9G1l?= Glisse <jglisse@redhat.com>,
        Ralph Campbell <rcampbell@nvidia.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Peter Zijlstra <peterz@infradead.org>,
        Dave Airlie <airlied@redhat.com>,
        "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
        Thomas Hellstrom <thellstrom@vmware.com>,
        Souptick Joarder <jrdr.linux@gmail.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org,
        Catalin Marinas <Catalin.Marinas@arm.com>
Subject: Re: [PATCH v2] mm: fix double page fault on arm64 if PTE_AF is
 cleared
Message-ID: <20190909212712.GE29434@bombadil.infradead.org>
References: <20190906135747.211836-1-justin.he@arm.com>
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On Fri, Sep 06, 2019 at 09:57:47PM +0800, Jia He wrote:
> +		if (!pte_young(vmf->orig_pte)) {
> +			entry = pte_mkyoung(vmf->orig_pte);
> +			if (ptep_set_access_flags(vmf->vma, vmf->address,
> +				vmf->pte, entry, 0))
> +				update_mmu_cache(vmf->vma, vmf->address,
> +						vmf->pte);
> +		}
> +

Oh, btw, why call update_mmu_cache() here?  All you've done is changed
the 'accessed' bit.  What is any architecture supposed to do in response
to this?