From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qc0-f171.google.com (mail-qc0-f171.google.com [209.85.216.171]) by kanga.kvack.org (Postfix) with ESMTP id 1020D6B0069 for ; Tue, 7 Oct 2014 13:15:35 -0400 (EDT) Received: by mail-qc0-f171.google.com with SMTP id i17so6165852qcy.2 for ; Tue, 07 Oct 2014 10:15:34 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com. [209.132.183.28]) by mx.google.com with ESMTPS id y19si26938247qaw.92.2014.10.07.10.15.32 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 07 Oct 2014 10:15:34 -0700 (PDT) Message-ID: <54341F77.6060400@redhat.com> Date: Tue, 07 Oct 2014 19:14:31 +0200 From: Paolo Bonzini MIME-Version: 1.0 Subject: Re: [PATCH 10/17] mm: rmap preparation for remap_anon_pages References: <1412356087-16115-1-git-send-email-aarcange@redhat.com> <1412356087-16115-11-git-send-email-aarcange@redhat.com> <20141006085540.GD2336@work-vm> <20141006164156.GA31075@redhat.com> <20141007170731.GO2404@work-vm> In-Reply-To: <20141007170731.GO2404@work-vm> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: "Dr. David Alan Gilbert" , Linus Torvalds Cc: Andrea Arcangeli , qemu-devel@nongnu.org, KVM list , Linux Kernel Mailing List , linux-mm , Linux API , Andres Lagar-Cavilla , Dave Hansen , Rik van Riel , Mel Gorman , Andy Lutomirski , Andrew Morton , Sasha Levin , Hugh Dickins , Peter Feiner , Christopher Covington , Johannes Weiner , Android Kernel Team , Robert Love , Dmitry Adamushko , Neil Brown , Mike Hommey , Taras Glek , Jan Kara , KOSAKI Motohiro , Michel Lespinasse , Minchan Kim , Keith Packard , "Huangpeng (Peter)" , Isaku Yamahata , Anthony Liguori , Stefan Hajnoczi , Wenchao Xia , Andrew Jones , Juan Quintela Il 07/10/2014 19:07, Dr. David Alan Gilbert ha scritto: >> > >> > So I'd *much* rather have a "write()" style interface (ie _copying_ >> > bytes from user space into a newly allocated page that gets mapped) >> > than a "remap page" style interface > Something like that might work for the postcopy case; it doesn't work > for some of the other uses that need to stop a page being changed by the > guest, but then need to somehow get a copy of that page internally to QEMU, > and perhaps provide it back later. I cannot parse this. Which uses do you have in mind? Is it for QEMU-specific or is it for other applications of userfaults? As long as the page is atomically mapped, I'm not sure what the difference from remap_anon_pages are (as far as the destination page is concerned). Are you thinking of having userfaults enabled on the source as well? Paolo > remap_anon_pages worked for those cases > as well; I can't think of another current way of doing it in userspace. -- 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