From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753694Ab1ABMRx (ORCPT ); Sun, 2 Jan 2011 07:17:53 -0500 Received: from ist.d-labs.de ([213.239.218.44]:58283 "EHLO mx01.d-labs.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752789Ab1ABMRw (ORCPT ); Sun, 2 Jan 2011 07:17:52 -0500 Date: Sun, 2 Jan 2011 13:17:47 +0100 From: Florian Mickler To: Dan Carpenter Cc: Jeff Mahoney , Andrew Morton , "David S. Miller" , balbir@linux.vnet.ibm.com, Linux Kernel Mailing List Subject: Re: [PATCH] taskstats: Use better ifdef for alignment Message-ID: <20110102131747.3e79107a@schatten.dmk.lab> In-Reply-To: <20110101165135.GJ1886@bicker> References: <4D1BCE58.4000902@suse.com> <20101229161418.d34bf0d4.akpm@linux-foundation.org> <4D1C180A.20000@suse.com> <20101229213243.891b0db5.akpm@linux-foundation.org> <4D1CAAA1.8030106@suse.com> <20110101171946.6179c3b6@schatten.dmk.lab> <20110101165135.GJ1886@bicker> X-Mailer: Claws Mail 3.7.6cvs31 (GTK+ 2.20.1; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 1 Jan 2011 19:51:35 +0300 Dan Carpenter wrote: > On Sat, Jan 01, 2011 at 05:19:46PM +0100, Florian Mickler wrote: > > Is there already a patch available or integrated into iotop which > > fixes this? I'd think that if the kernel could wait on fixed iotop's to > > be distributed it would be easier to sell the breakage on bugzilla & > > co... > > > > The story is that 4be2c95d1f "taskstats: pad taskstats netlink response > for aligment issues on ia64" broke iotop on 64 bit processors (32 bit > was unaffected). This patch fixes it for x86-64 and powerpc-64. > > On the other 64 bit processors iotop works but instead you get a message > in dmesg: > kernel unaligned access to 0xe000023879dca9bc, ip=0xa000000100133d10 > > So on those arches you were already getting posts to bugzilla etc. Now > those people can upgrade the kernel and download iotop version 0.4.2 or > higher. > > regards, > dan carpenter > Ah ok. And probably bug #24272 is related to this. If I understood it correctly 85893120 fixed some runtime warnings (or more exactly the misaligning) and broke iotop in the process (on all of 64 bit). 4be2c95d1f undid that and enhanced the netlink messages on IA64 archs with a new type to fix the alignment and now it's changed to align well on all archs that need alignment, leaving archs unbroken that have efficient unaligned access (x86-64 and powerpc-64). Nice. And to answer my original question, i just checked out (some?/the?) iotop sources from git://repo.or.cz/iotop.git and found a fix[1] for the issue with 85893120. Is iotop parsing fixed to ignore the null-field in the meantime? Thx, Flo [1]git://repo.or.cz/iotop.git:commit 08211d209ae8fc7e67ea3bebb09979ff61c70f97 Author: Guillaume Chazarain Date: Sat Sep 4 13:57:43 2010 +0200 Instead of assuming the pid field is 4 bytes long, take its length from the header. This is needed for http://lkml.org/lkml/2010/2/12/167 [PATCH] delayacct: align to 8 byte boundary on 64-bit systems