Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751872AbZIHTAQ (ORCPT ); Tue, 8 Sep 2009 15:00:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751414AbZIHTAP (ORCPT ); Tue, 8 Sep 2009 15:00:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:39833 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751383AbZIHTAO (ORCPT ); Tue, 8 Sep 2009 15:00:14 -0400 Message-ID: <4AA6A989.60907@redhat.com> Date: Tue, 08 Sep 2009 14:59:21 -0400 From: Rik van Riel Organization: Red Hat, Inc User-Agent: Thunderbird 2.0.0.17 (X11/20080915) MIME-Version: 1.0 To: Hugh Dickins CC: Andrew Morton , Mel Gorman , Jeff Chua , KAMEZAWA Hiroyuki , KOSAKI Motohiro , Linus Torvalds , Nick Piggin , linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 4/8] mm: FOLL_DUMP replace FOLL_ANON References: In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1040 Lines: 24 Hugh Dickins wrote: > The "FOLL_ANON optimization" and its use_zero_page() test have caused > confusion and bugs: why does it test VM_SHARED? for the very good but > unsatisfying reason that VMware crashed without. As we look to maybe > reinstating anonymous use of the ZERO_PAGE, we need to sort this out. > > Easily done: it's silly for __get_user_pages() and follow_page() to > be guessing whether it's safe to assume that they're being used for > a coredump (which can take a shortcut snapshot where other uses must > handle a fault) - just tell them with GUP_FLAGS_DUMP and FOLL_DUMP. > > get_dump_page() doesn't even want a ZERO_PAGE: an error suits fine. > > Signed-off-by: Hugh Dickins Acked-by: Rik van Riel -- All rights reversed. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/