linux-kernel - Re: [PATCH V2 1/2] mm/autonuma: Let architecture override how the write bit should be stashed in a protnone pte.

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Message-Id: <874lzxm41g.fsf@concordia.ellerman.id.au>
Date:   Tue, 14 Feb 2017 21:59:23 +1100
From:   Michael Ellerman <michaele@....ibm.com>
To:     "Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.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, linuxppc-dev@...ts.ozlabs.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 1/2] mm/autonuma: Let architecture override how the write bit should be stashed in a protnone pte.

"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com> writes:

> 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

Ah OK, I missed those.

In that case these two should probably go via Andrew's tree.

cheers