From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752086AbdBNF4F (ORCPT ); Tue, 14 Feb 2017 00:56:05 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:53639 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750751AbdBNF4D (ORCPT ); Tue, 14 Feb 2017 00:56:03 -0500 Subject: Re: [PATCH V2 1/2] mm/autonuma: Let architecture override how the write bit should be stashed in a protnone pte. To: Michael Ellerman , akpm@linux-foundation.org, Rik van Riel , Mel Gorman , paulus@ozlabs.org, benh@kernel.crashing.org References: <1487050314-3892-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <1487050314-3892-2-git-send-email-aneesh.kumar@linux.vnet.ibm.com> <87poilmien.fsf@concordia.ellerman.id.au> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org From: "Aneesh Kumar K.V" Date: Tue, 14 Feb 2017 11:25:48 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.7.0 MIME-Version: 1.0 In-Reply-To: <87poilmien.fsf@concordia.ellerman.id.au> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 17021405-0016-0000-0000-000006291E48 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00006613; HX=3.00000240; KW=3.00000007; PH=3.00000004; SC=3.00000203; SDB=6.00821666; UDB=6.00401887; IPR=6.00599120; BA=6.00005135; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00014273; XFM=3.00000011; UTC=2017-02-14 05:56:01 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17021405-0017-0000-0000-0000376040D3 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2017-02-14_03:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1612050000 definitions=main-1702140061 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 14 February 2017 11:19 AM, Michael Ellerman wrote: > "Aneesh Kumar K.V" 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