Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757745AbXLLEER (ORCPT ); Tue, 11 Dec 2007 23:04:17 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758040AbXLLEDc (ORCPT ); Tue, 11 Dec 2007 23:03:32 -0500 Received: from cantor2.suse.de ([195.135.220.15]:43207 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758012AbXLLEDb (ORCPT ); Tue, 11 Dec 2007 23:03:31 -0500 Date: Wed, 12 Dec 2007 05:03:28 +0100 From: Nick Piggin To: Christian Borntraeger Cc: Andrew Morton , Linux Kernel Mailing List , linux-fsdevel@vger.kernel.org, "Eric W. Biederman" , rob@landley.net, Jens Axboe , cotte@de.ibm.com Subject: Re: [patch] mm: fix XIP file writes Message-ID: <20071212040328.GA23914@wotan.suse.de> References: <20071204042628.GA26636@wotan.suse.de> <20071204113549.GA6751@wotan.suse.de> <20071204130050.GB6751@wotan.suse.de> <200712101538.20619.borntraeger@de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200712101538.20619.borntraeger@de.ibm.com> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1713 Lines: 39 On Mon, Dec 10, 2007 at 03:38:20PM +0100, Christian Borntraeger wrote: > Hi Nick, > > > Here we go. See, brd already found a bug ;) > > Can you apply the ext2 XIP patch too? And I'll resend the brd XIP patch. > [...] > > Writing to XIP files at a non-page-aligned offset results in data corruption > > because the writes were always sent to the start of the page. > [...] > > @@ -314,7 +314,7 @@ __xip_file_write(struct file *filp, cons > > fault_in_pages_readable(buf, bytes); > > kaddr = kmap_atomic(page, KM_USER0); > > copied = bytes - > > - __copy_from_user_inatomic_nocache(kaddr, buf, bytes); > > + __copy_from_user_inatomic_nocache(kaddr + offset, buf, bytes); > > kunmap_atomic(kaddr, KM_USER0); > > flush_dcache_page(page); > > I asked myself why this problem never happened before. So I asked our testers > to reproduce this problem on 2.6.23 and service levels. As the testcase did > not trigger, I looked into the 2.6.23 code. This problem was introduced by > commit 4a9e5ef1f4f15205e477817a5cefc34bd3f65f55 (mm: write iovec cleanup from > Nick Piggin) during 2.6.24-rc: > --------snip------- > - copied = filemap_copy_from_user(page, offset, buf, bytes); > [...] > + copied = bytes - > + __copy_from_user_inatomic_nocache(kaddr, buf, bytes); > ------------------- > > So yes, its good to have xip on brd. It even tests your changes ;-) > Good news is, that we dont need anything for stable. Heh ;) that explains a lot. Thanks! -- 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/