From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933263Ab0ECQg1 (ORCPT ); Mon, 3 May 2010 12:36:27 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:51418 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759063Ab0ECQg0 (ORCPT ); Mon, 3 May 2010 12:36:26 -0400 Date: Mon, 3 May 2010 09:34:14 -0700 (PDT) From: Linus Torvalds To: Rik van Riel cc: akpm@linux-foundation.org, Mel Gorman , Linux-MM , LKML , Minchan Kim , KAMEZAWA Hiroyuki , Andrea Arcangeli , Christoph Lameter Subject: Re: [PATCH 2/2] mm: fix race between shift_arg_pages and rmap_walk In-Reply-To: <20100503121929.260ed5ee@annuminas.surriel.com> Message-ID: References: <20100503121743.653e5ecc@annuminas.surriel.com> <20100503121929.260ed5ee@annuminas.surriel.com> User-Agent: Alpine 2.00 (LFD 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 3 May 2010, Rik van Riel wrote: > > migrate.c requires rmap to be able to find all ptes mapping a page at > all times, otherwise the migration entry can be instantiated, but it > can't be removed if the second rmap_walk fails to find the page. Please correct me if I'm wrong, but this patch looks like pure and utter garbage. It looks like it makes execve() do a totally insane "create and then immediately destroy temporary vma and anon_vma chain" for a case that is unlikely to ever matter. In fact, for a case that isn't even normally _enabled_, namely migration. Why would we want to slow down execve() for that? Linus