From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752126AbdBFW04 (ORCPT ); Mon, 6 Feb 2017 17:26:56 -0500 Received: from outbound-smtp07.blacknight.com ([46.22.139.12]:47987 "EHLO outbound-smtp07.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751447AbdBFW0z (ORCPT ); Mon, 6 Feb 2017 17:26:55 -0500 Date: Mon, 6 Feb 2017 22:26:42 +0000 From: Mel Gorman To: "Aneesh Kumar K.V" Cc: akpm@linux-foundation.org, Rik van Riel , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/autonuma: don't use set_pte_at when updating protnone ptes Message-ID: <20170206222642.u2e5ip4h2udaehr4@techsingularity.net> References: <1486400776-28114-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: <1486400776-28114-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> User-Agent: Mutt/1.6.2 (2016-07-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Feb 06, 2017 at 10:36:16PM +0530, Aneesh Kumar K.V wrote: > Architectures like ppc64, use privilege access bit to mark pte non accessible. > This implies that kernel can do a copy_to_user to an address marked for numa fault. > This also implies that there can be a parallel hardware update for the pte. > set_pte_at cannot be used in such scenarios. Hence switch the pte > update to use ptep_get_and_clear and set_pte_at combination. > > Signed-off-by: Aneesh Kumar K.V Yeah, ok. The main thing is that it still avoids doing an unnecessary TLB flush so Acked-by: Mel Gorman -- Mel Gorman SUSE Labs