From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail138.messagelabs.com (mail138.messagelabs.com [216.82.249.35]) by kanga.kvack.org (Postfix) with SMTP id D64C26B003D for ; Fri, 8 May 2009 04:50:37 -0400 (EDT) Received: by an-out-0708.google.com with SMTP id d14so720477and.26 for ; Fri, 08 May 2009 01:51:24 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20090505212139.GA2559@cmpxchg.org> References: <20090501181449.GA8912@cmpxchg.org> <1241430874-12667-1-git-send-email-hannes@cmpxchg.org> <20090505122442.6271c7da.akpm@linux-foundation.org> <20090505203807.GB2428@cmpxchg.org> <20090505140517.bef78dd3.akpm@linux-foundation.org> <20090505212139.GA2559@cmpxchg.org> Date: Fri, 8 May 2009 17:51:24 +0900 Message-ID: Subject: Re: [patch 1/3] mm: introduce follow_pte() From: Magnus Damm Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org To: Johannes Weiner Cc: Andrew Morton , linux-media@vger.kernel.org, hverkuil@xs4all.nl, lethal@linux-sh.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On Wed, May 6, 2009 at 6:21 AM, Johannes Weiner wrote: > On Tue, May 05, 2009 at 02:05:17PM -0700, Andrew Morton wrote: >> On Tue, 5 May 2009 22:38:07 +0200 >> Johannes Weiner wrote: >> > On Tue, May 05, 2009 at 12:24:42PM -0700, Andrew Morton wrote: >> > > On Mon, =A04 May 2009 11:54:32 +0200 >> > > Johannes Weiner wrote: >> > > >> > > > A generic readonly page table lookup helper to map an address spac= e >> > > > and an address from it to a pte. >> > > >> > > umm, OK. >> > > >> > > Is there actually some point to these three patches? =A0If 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 >> > =A0 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(). >> >> So we could bundle these patches with Magnus's patchset, or we could >> consider these three patches as a cleanup or something. >> >> Given that 3/3 introduces an unused function, I'm inclined to sit tight >> and await Magnus's work. > > Yeah, I didn't see the video guys responding on Magnus' patch yet, so > let's wait for them. > > Magnus, the actual conversion of your code should be trivial, could > you respin it on top of these three patches using follow_pfn() then? So I tested the patches in -mm (1/3, 2/3, 3/3) together with the zero copy patch and everything seems fine. Feel free to add acks from me, least for patch 1/3 and 3/3 - i know too little about the generic case to say anything about 2/3. Acked-by: Magnus Damm I'll send V3 of my zero copy patch in a little while. Thanks a lot for the = help! Cheers, / magnus -- 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