From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from zps37.corp.google.com (zps37.corp.google.com [172.25.146.37]) by smtp-out.google.com with ESMTP id kB1JWauV013214 for ; Fri, 1 Dec 2006 11:32:36 -0800 Received: from nf-out-0910.google.com (nfap46.prod.google.com [10.48.67.46]) by zps37.corp.google.com with ESMTP id kB1JWS1N007241 for ; Fri, 1 Dec 2006 11:32:29 -0800 Received: by nf-out-0910.google.com with SMTP id p46so262718nfa for ; Fri, 01 Dec 2006 11:32:28 -0800 (PST) Message-ID: <6599ad830612011132i3e70ab38ye3bc8e48f879fea3@mail.gmail.com> Date: Fri, 1 Dec 2006 11:32:27 -0800 From: "Paul Menage" Subject: Re: [RFC][PATCH 0/1] Node-based reclaim/migration In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20061129030655.941148000@menage.corp.google.com> <6599ad830611301153i231765a0ke46846bcb73258d6@mail.gmail.com> <6599ad830611301207q4e4ab485lb0d3c99680db5a2a@mail.gmail.com> <6599ad830611301333v48f2da03g747c088ed3b4ad60@mail.gmail.com> <6599ad830611301548y66e5e66eo2f61df940a66711a@mail.gmail.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Christoph Lameter Cc: KAMEZAWA Hiroyuki , Hugh Dickins , linux-mm@kvack.org, akpm@osdl.org List-ID: On 11/30/06, Christoph Lameter wrote: > On Thu, 30 Nov 2006, Paul Menage wrote: > > > Don't we need to bump the mapcount? If we don't, then the page gets > > unmapped by the migration prep, and if we race with anyone trying to > > map it they may allocate a new anon_vma and replace it. > > Allocate a new vma for an existing anon page? That never happens. We may > do COW in which case the page is copied. I was thinking of a new anon_vma, rather than a new vma - but I guess that even if we do race with someone who's faulting on the page and pulling it from the swap cache, they'll just set the page mapping to the same value as it is already, rather than setting it to a new value. So you're right, not a problem. Paul -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org