Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755898AbZCRXhl (ORCPT ); Wed, 18 Mar 2009 19:37:41 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751976AbZCRXhc (ORCPT ); Wed, 18 Mar 2009 19:37:32 -0400 Received: from gw.goop.org ([64.81.55.164]:44908 "EHLO mail.goop.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751955AbZCRXhb (ORCPT ); Wed, 18 Mar 2009 19:37:31 -0400 Message-ID: <49C185B4.90004@goop.org> Date: Wed, 18 Mar 2009 16:37:24 -0700 From: Jeremy Fitzhardinge User-Agent: Thunderbird 2.0.0.19 (X11/20090105) MIME-Version: 1.0 To: Shentino CC: Avi Kivity , Nick Piggin , Linux Kernel Mailing List , Linux Memory Management List , Xen-devel , Jan Beulich , Ingo Molnar Subject: Re: Question about x86/mm/gup.c's use of disabled interrupts References: <49C148AF.5050601@goop.org> <49C16411.2040705@redhat.com> <49C1665A.4080707@goop.org> <49C16A48.4090303@redhat.com> <49C17230.20109@goop.org> <49C17880.7080109@redhat.com> <49C17BD8.6050609@goop.org> <49C17E22.9040807@redhat.com> <70513aa50903181617r418ec23s744544dccfd812e8@mail.gmail.com> In-Reply-To: <70513aa50903181617r418ec23s744544dccfd812e8@mail.gmail.com> X-Enigmail-Version: 0.95.6 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: 597 Lines: 15 Shentino wrote: > But, does a CPU running a task in userspace effectively have a read > lock on the page tables? No. A process has its own user pagetable which the kernel maintains on its behalf. The kernel will briefly take locks on it while doing modifications, mostly to deal with multithreaded usermode code running on multiple cpus. J -- 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/