From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail172.messagelabs.com (mail172.messagelabs.com [216.82.254.3]) by kanga.kvack.org (Postfix) with SMTP id 469D96B007E for ; Tue, 8 Sep 2009 15:00:05 -0400 (EDT) Message-ID: <4AA6A989.60907@redhat.com> Date: Tue, 08 Sep 2009 14:59:21 -0400 From: Rik van Riel MIME-Version: 1.0 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: owner-linux-mm@kvack.org 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 List-ID: 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, 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