Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755080Ab1BMV4k (ORCPT ); Sun, 13 Feb 2011 16:56:40 -0500 Received: from paneer.cc.columbia.edu ([128.59.29.4]:41771 "EHLO paneer.cc.columbia.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752467Ab1BMV4e (ORCPT ); Sun, 13 Feb 2011 16:56:34 -0500 Message-ID: <4D58537C.3020409@rath.org> Date: Sun, 13 Feb 2011 16:56:12 -0500 From: Nikolaus Rath User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.9.2.13) Gecko/20101208 Thunderbird/3.1.7 MIME-Version: 1.0 To: Brice Goglin CC: LKML Subject: Re: virt_to_page for userspace pointers References: <87k4hgn8qa.fsf@inspiron.ap.columbia.edu> <878vxuxkfr.fsf@inspiron.ap.columbia.edu> <4D4DC2D6.8030905@ens-lyon.org> <4D583E17.80606@rath.org> <4D5840F6.8030401@ens-lyon.org> In-Reply-To: <4D5840F6.8030401@ens-lyon.org> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-No-Spam-Score: Local Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1513 Lines: 41 On 02/13/2011 03:37 PM, Brice Goglin wrote: > Le 13/02/2011 21:24, Nikolaus Rath a écrit : >> On 02/05/2011 04:36 PM, Brice Goglin wrote: >> >>>> Is there an equivalent function to virt_to_page (and virt_to_phys) that >>>> works with userspace pointers? Or do I have to manually walk through the >>>> page tables? In the later case, are there any examples of this kind of >>>> search that I could use as a basis? >>>> >>>> >>> You probably want get_user_pages() (or get_user_pages_fast()). >>> >> Thanks for the pointer, that already helped a lot! >> >> I would, however, prefer a more primitive function that just gives me >> the struct page without locking it. And if the page is swapped out, I'd >> rather get a NULL pointer than having a page frame allocated. Is there >> anything like that? >> > > If you don't lock the page, you have no guarantee that it won't get > swapped out or migrated while you look at the physical page. That's fine, I know that if the page is there at all then it has been locked by a (different) kernel driver. Is there any way to find out what I want? Thanks, -Nikolaus -- »Time flies like an arrow, fruit flies like a Banana.« PGP fingerprint: 5B93 61F8 4EA2 E279 ABF6 02CF A9AD B7F8 AE4E 425C -- 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/