From: Catalin Marinas <catalin.marinas@arm.com>
To: Will Deacon <will@kernel.org>
Cc: Jia He <justin.he@arm.com>, Mark Rutland <mark.rutland@arm.com>,
James Morse <james.morse@arm.com>, Marc Zyngier <maz@kernel.org>,
Matthew Wilcox <willy@infradead.org>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Suzuki Poulose <Suzuki.Poulose@arm.com>,
Borislav Petkov <bp@alien8.de>, "H. Peter Anvin" <hpa@zytor.com>,
x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
Andrew Morton <akpm@linux-foundation.org>,
hejianet@gmail.com, Kaly Xin <Kaly.Xin@arm.com>,
nd@arm.com
Subject: Re: [PATCH v12 0/4] fix double page fault in cow_user_page for pfn mapping
Date: Wed, 16 Oct 2019 15:32:52 +0100 [thread overview]
Message-ID: <20191016143252.GJ49619@arrakis.emea.arm.com> (raw)
In-Reply-To: <20191015001834.wwkd46t6dwicta7n@willie-the-truck>
On Tue, Oct 15, 2019 at 01:18:34AM +0100, Will Deacon wrote:
> On Fri, Oct 11, 2019 at 10:09:35PM +0800, Jia He wrote:
> > When we tested pmdk unit test vmmalloc_fork TEST1 in arm64 guest, there
> > will be a double page fault in __copy_from_user_inatomic of cow_user_page.
> >
> > As told by Catalin: "On arm64 without hardware Access Flag, copying from
> > user will fail because the pte is old and cannot be marked young. So we
> > always end up with zeroed page after fork() + CoW for pfn mappings. we
> > don't always have a hardware-managed access flag on arm64."
> >
> > -Changes
> > v12:
> > refine PATCH 01, remove the !! since C languages can convert unsigned
> > to bool (Catalin)
>
> Thanks. I think it's a bit late to take something like this for 5.4 now,
> especially as the current behaviour has always been there. Hopefully
> somebody can queue it for 5.5 instead.
I can queue this through the arm64 tree for 5.5 if I get an ack on the
x86 patch (3/4) or I don't hear any complaints.
--
Catalin
prev parent reply other threads:[~2019-10-16 14:33 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-10-11 14:09 Jia He
2019-10-11 14:09 ` [PATCH v12 1/4] arm64: cpufeature: introduce helper cpu_has_hw_af() Jia He
2019-10-11 14:09 ` [PATCH v12 2/4] arm64: mm: implement arch_faults_on_old_pte() on arm64 Jia He
2019-10-11 14:09 ` [PATCH v12 3/4] x86/mm: implement arch_faults_on_old_pte() stub on x86 Jia He
2019-10-11 14:09 ` [PATCH v12 4/4] mm: fix double page fault on arm64 if PTE_AF is cleared Jia He
2019-10-15 0:18 ` [PATCH v12 0/4] fix double page fault in cow_user_page for pfn mapping Will Deacon
2019-10-16 14:32 ` Catalin Marinas [this message]
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