Date: Wed, 21 Jun 2017 11:40:17 +0100
From: Catalin Marinas <catalin.marinas@arm.com>
To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Vlastimil Babka <vbabka@suse.cz>, Vineet Gupta <vgupta@synopsys.com>,
        Russell King <linux@armlinux.org.uk>,
        Will Deacon <will.deacon@arm.com>, Ralf Baechle <ralf@linux-mips.org>,
        "David S. Miller" <davem@davemloft.net>,
        "Aneesh Kumar K . V" <aneesh.kumar@linux.vnet.ibm.com>,
        Martin Schwidefsky <schwidefsky@de.ibm.com>,
        Heiko Carstens <heiko.carstens@de.ibm.com>,
        Andrea Arcangeli <aarcange@redhat.com>, linux-arch@vger.kernel.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Ingo Molnar <mingo@kernel.org>, "H . Peter Anvin" <hpa@zytor.com>,
        Thomas Gleixner <tglx@linutronix.de>
Subject: Re: [PATCHv2 1/3] x86/mm: Provide pmdp_establish() helper
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On Wed, Jun 21, 2017 at 12:53:03PM +0300, Kirill A. Shutemov wrote:
> On Tue, Jun 20, 2017 at 04:54:38PM +0100, Catalin Marinas wrote:
> > For arm64, I don't see the point of a cmpxchg, so something like below
> > would do (it needs proper testing though):
> 
> Right. cmpxchg is required for x86 PAE, as it has sizeof(pmd_t) >
> sizeof(long). We don't have 8-byte xchg() there.
> 
> Thanks, for the patch. I assume, I can use your signed-off-by, right?

Yes. And maybe some text (well, I just copied yours):

---------------8<--------------
arm64: Provide pmdp_establish() helper

We need an atomic way to setup pmd page table entry, avoiding races with
CPU setting dirty/accessed bits. This is required to implement
pmdp_invalidate() that doesn't lose these bits.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
---------------8<--------------

> Any chance you could help me with arm too?

I'll have a look.

-- 
Catalin