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Date: Wed, 13 Dec 2017 16:04:53 +0100
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [patch 05/16] mm: Allow special mappings with user access cleared
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To: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Dan Williams <dan.j.williams@intel.com>, Dave Hansen <dave.hansen@intel.com>, Andy Lutomirski <luto@kernel.org>, Thomas Gleixner <tglx@linutronix.de>, LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>, Linus Torvalds <torvalds@linux-foundation.org>, Borislav Petkov <bpetkov@suse.de>, Greg KH <gregkh@linuxfoundation.org>, Kees Cook <keescook@google.com>, Hugh Dickins <hughd@google.com>, Brian Gerst <brgerst@gmail.com>, Josh Poimboeuf <jpoimboe@redhat.com>, Denys Vlasenko <dvlasenk@redhat.com>, Boris Ostrovsky <boris.ostrovsky@oracle.com>, Juergen Gross <jgross@suse.com>, David Laight <David.Laight@aculab.com>, Eduardo Valentin <eduval@amazon.com>, aliguori@amazon.com, Will Deacon <will.deacon@arm.com>, "linux-mm@kvack.org" <linux-mm@kvack.org>, kirill.shutemov@linux.intel.com, aneesh.kumar@linux.vnet.ibm.com

On Wed, Dec 13, 2017 at 04:00:07PM +0100, Peter Zijlstra wrote:
> On Wed, Dec 13, 2017 at 05:43:39PM +0300, Kirill A. Shutemov wrote:
> > > am I perchance looking at the wrong tee?
> > 
> > I'm looking at Linus' tree.
> 
> Clearly I'm not synced up enough... :/
> 
> > It was changed recently:
> > 	5c9d2d5c269c ("mm: replace pte_write with pte_access_permitted in fault + gup paths")
> > 
> 
> Indeed. So FOLL_GET should also get these tests and, as you said, the
> other levels too.
> 
> I would like FOLL_POPULATE (doesn't have FOLL_GET) to be allowed
> 'access'.

Similarly, should we avoid arch_vma_access_permitted() if !FOLL_GET ?

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