Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752000AbdGGHIL (ORCPT ); Fri, 7 Jul 2017 03:08:11 -0400 Received: from mail-pf0-f195.google.com ([209.85.192.195]:36636 "EHLO mail-pf0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750848AbdGGHIK (ORCPT ); Fri, 7 Jul 2017 03:08:10 -0400 Message-ID: <1499411222.23251.5.camel@gmail.com> Subject: Re: [RFC v5 01/11] mm: Dont assume page-table invariance during faults From: Balbir Singh To: Laurent Dufour , paulmck@linux.vnet.ibm.com, peterz@infradead.org, akpm@linux-foundation.org, kirill@shutemov.name, ak@linux.intel.com, mhocko@kernel.org, dave@stgolabs.net, jack@suse.cz, Matthew Wilcox Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, haren@linux.vnet.ibm.com, khandual@linux.vnet.ibm.com, npiggin@gmail.com, Tim Chen Date: Fri, 07 Jul 2017 17:07:02 +1000 In-Reply-To: <1497635555-25679-2-git-send-email-ldufour@linux.vnet.ibm.com> References: <1497635555-25679-1-git-send-email-ldufour@linux.vnet.ibm.com> <1497635555-25679-2-git-send-email-ldufour@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.22.6-1ubuntu1 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 551 Lines: 15 On Fri, 2017-06-16 at 19:52 +0200, Laurent Dufour wrote: > From: Peter Zijlstra > > One of the side effects of speculating on faults (without holding > mmap_sem) is that we can race with free_pgtables() and therefore we > cannot assume the page-tables will stick around. > > Remove the relyance on the pte pointer. ^^ reliance Looking at the changelog and the code the impact is not clear. It looks like after this patch we always assume the pte is not the same. What is the impact of this patch? Balbir Singh.