Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750827AbWI3RF6 (ORCPT ); Sat, 30 Sep 2006 13:05:58 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751305AbWI3RF5 (ORCPT ); Sat, 30 Sep 2006 13:05:57 -0400 Received: from caramon.arm.linux.org.uk ([217.147.92.249]:63752 "EHLO caramon.arm.linux.org.uk") by vger.kernel.org with ESMTP id S1750827AbWI3RF4 (ORCPT ); Sat, 30 Sep 2006 13:05:56 -0400 Date: Sat, 30 Sep 2006 18:05:48 +0100 From: Russell King To: Miklos Szeredi Cc: dhylands@gmail.com, guinan@bluebutton.com, linux-kernel@vger.kernel.org Subject: Re: get_user_pages() cache issues on ARM Message-ID: <20060930170548.GA24949@flint.arm.linux.org.uk> Mail-Followup-To: Miklos Szeredi , dhylands@gmail.com, guinan@bluebutton.com, linux-kernel@vger.kernel.org References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1276 Lines: 35 On Sat, Sep 30, 2006 at 06:59:50PM +0200, Miklos Szeredi wrote: > Hi Russell, > > The get_user_pages() vs dcache coherency issue still seems to be > unresolved on ARM. > > See flush_anon_page() and flush_kernel_dcache_page() in > Documentation/cachetlb.txt and their implementation on PARISC. > > Can you please take a look at this? I'm sorry, I don't think I have sufficient understanding of the Linux VM to look at these issues anymore. The questions I have are: - where do these pages that get_user_pages() finds and calls flush_anon_page() on come from? - why is the current ARM flush_dcache_page() (which is also called after flush_anon_page()) not sufficient? - if we implement flush_anon_page() does that mean that we end up flushing multiple times in some circumstances? If so, how do we avoid this? I'm really serious - I no longer understand the Linux VM sufficiently to get this stuff right. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core - 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/