From: Catalin Marinas <catalin.marinas@arm.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: "Jia He" <justin.he@arm.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Jérôme 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
Subject: Re: [PATCH v2] mm: fix double page fault on arm64 if PTE_AF is cleared
Date: Tue, 10 Sep 2019 10:08:45 +0100 [thread overview]
Message-ID: <20190910090845.GD14442@C02TF0J2HF1T.local> (raw)
In-Reply-To: <20190909212712.GE29434@bombadil.infradead.org>
On Mon, Sep 09, 2019 at 02:27:12PM -0700, Matthew Wilcox wrote:
> 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?
For arm64 and x86 that's a no-op but an architecture with software TLBs
may preload them to avoid a subsequent fault on access after the pte was
made young.
--
Catalin
next prev parent reply other threads:[~2019-09-10 9:09 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-06 13:57 [PATCH v2] mm: fix double page fault on arm64 if PTE_AF is cleared Jia He
2019-09-06 14:57 ` Matthew Wilcox
2019-09-10 9:15 ` Catalin Marinas
2019-09-09 21:27 ` Matthew Wilcox
2019-09-10 9:08 ` Catalin Marinas [this message]
2019-09-10 9:29 ` Kirill A. Shutemov
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