From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757939AbZEEUkX (ORCPT ); Tue, 5 May 2009 16:40:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753187AbZEEUkH (ORCPT ); Tue, 5 May 2009 16:40:07 -0400 Received: from cmpxchg.org ([85.214.51.133]:38182 "EHLO cmpxchg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752794AbZEEUkG (ORCPT ); Tue, 5 May 2009 16:40:06 -0400 Date: Tue, 5 May 2009 22:38:07 +0200 From: Johannes Weiner To: Andrew Morton Cc: magnus.damm@gmail.com, linux-media@vger.kernel.org, hverkuil@xs4all.nl, lethal@linux-sh.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [patch 1/3] mm: introduce follow_pte() Message-ID: <20090505203807.GB2428@cmpxchg.org> References: <20090501181449.GA8912@cmpxchg.org> <1241430874-12667-1-git-send-email-hannes@cmpxchg.org> <20090505122442.6271c7da.akpm@linux-foundation.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090505122442.6271c7da.akpm@linux-foundation.org> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 05, 2009 at 12:24:42PM -0700, Andrew Morton wrote: > On Mon, 4 May 2009 11:54:32 +0200 > Johannes Weiner wrote: > > > A generic readonly page table lookup helper to map an address space > > and an address from it to a pte. > > umm, OK. > > Is there actually some point to these three patches? If so, what is it? Magnus needs to check for physical contiguity of a VMAs backing pages to support zero-copy exportation of video data to userspace. This series implements follow_pfn() so he can walk the VMA backing pages and ensure their PFNs are in linear order. [ This patch can be collapsed with 2/3, I just thought it would be easier to read the diffs when having them separate. ] 1/3 and 2/3: factor out the page table walk from follow_phys() into follow_pte(). 3/3: implement follow_pfn() on top of follow_pte().