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Date:   Tue, 14 Feb 2017 11:25:48 +0530
From:   "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>
To:     Michael Ellerman <michaele@....ibm.com>, akpm@...ux-foundation.org,
        Rik van Riel <riel@...riel.com>,
        Mel Gorman <mgorman@...hsingularity.net>, paulus@...abs.org,
        benh@...nel.crashing.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org
Subject: Re: [PATCH V2 1/2] mm/autonuma: Let architecture override how the
 write bit should be stashed in a protnone pte.



On Tuesday 14 February 2017 11:19 AM, Michael Ellerman wrote:
> "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com> writes:
>
>> Autonuma preserves the write permission across numa fault to avoid taking
>> a writefault after a numa fault (Commit: b191f9b106ea " mm: numa: preserve PTE
>> write permissions across a NUMA hinting fault"). Architecture can implement
>> protnone in different ways and some may choose to implement that by clearing Read/
>> Write/Exec bit of pte. Setting the write bit on such pte can result in wrong
>> behaviour. Fix this up by allowing arch to override how to save the write bit
>> on a protnone pte.
> This is pretty obviously a nop on arches that don't implement the new
> hooks, but it'd still be good to get an ack from someone in mm land
> before I merge it.


To get it apply cleanly you may need
http://ozlabs.org/~akpm/mmots/broken-out/mm-autonuma-dont-use-set_pte_at-when-updating-protnone-ptes.patch
http://ozlabs.org/~akpm/mmots/broken-out/mm-autonuma-dont-use-set_pte_at-when-updating-protnone-ptes-fix.patch

They are strictly not needed after the saved write patch. But I didn't 
request to drop them, because the patch helps us
to get closer to the goal of no ste_pte_at() call on present ptes.

-aneesh


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