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Subject: Re: [PATCH 16/34] x86, mm: simplify get_user_pages() PTE bit handling
To: Thomas Gleixner <tglx@linutronix.de>
References: <20151204011424.8A36E365@viggo.jf.intel.com>
 <20151204011446.DDC6435F@viggo.jf.intel.com>
 <alpine.DEB.2.11.1512081839471.3595@nanos>
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org,
        dave.hansen@linux.intel.com
From: Dave Hansen <dave@sr71.net>
Message-ID: <566721CE.1060800@sr71.net>
Date: Tue, 8 Dec 2015 10:30:38 -0800
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On 12/08/2015 10:01 AM, Thomas Gleixner wrote:
> static inline int pte_allows_gup(unsigned long pteval, int write)
> {
> 	unsigned long mask = _PAGE_PRESENT|_PAGE_USER;
> 
> 	if (write)
> 		mask |= _PAGE_RW;
> 
> 	if ((pteval & mask) != mask)
> 		return 0;
> 
> 	if (!__pkru_allows_pkey(pte_flags_pkey(pteval), write))
> 	   	return 0;
> 	return 1;
> }
> 
> and at the callsites do:
> 
>     if (pte_allows_gup(pte_val(pte, write))
> 
>     if (pte_allows_gup(pmd_val(pmd, write))
> 
>     if (pte_allows_gup(pud_val(pud, write))
> 
> Hmm?

Looks fine to me.  I'll do that.