From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752384AbZH2Nvy (ORCPT ); Sat, 29 Aug 2009 09:51:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752336AbZH2Nvv (ORCPT ); Sat, 29 Aug 2009 09:51:51 -0400 Received: from ppp-144-74.adsl.restena.lu ([158.64.144.74]:44865 "EHLO bonbons.gotdns.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752310AbZH2Nvt (ORCPT ); Sat, 29 Aug 2009 09:51:49 -0400 X-Greylist: delayed 487 seconds by postgrey-1.27 at vger.kernel.org; Sat, 29 Aug 2009 09:51:48 EDT Date: Sat, 29 Aug 2009 15:43:05 +0200 From: Bruno =?UTF-8?B?UHLDqW1vbnQ=?= To: Ed Cashin Cc: apw@canonical.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/1] aoe: ensure we initialise the request_queue correctly Message-ID: <20090829154305.723fd86c@neptune.home> In-Reply-To: <9ab0e087296715d764071d4d39542985@coraid.com> References: <1250872904-10993-1-git-send-email-apw@canonical.com> <9ab0e087296715d764071d4d39542985@coraid.com> X-Mailer: Claws Mail 3.7.2 (GTK+ 2.14.7; i686-pc-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 Mon, 24 August 2009 Ed Cashin wrote: > On Fri Aug 21 12:41:59 EDT 2009, apw@canonical.com wrote: > > We have been seeing oopses in very recent kernels when using the > > AOE driver. When attempting to mount remote devices we get a > > warning from the kobject layer: > > > > [ 2645.959090] kobject '' (ffff880059ca22c0): tried to add > > an uninitialized object, something is seriously wrong. > > > > Looking at the driver it seems to have always had an embedded > > request_queue and it is this that is throwing the error. It > > appears the intent is tha these would be allocated and released > > using helpers, and the lack of these leaves the object > > uninitialised and throws the error. It is unclear how this could > > ever have worked. > > This aoe driver does not handle I/O requests but provides its own > make_request function to blk_queue_make_request and handles bios > instead. > > The reason I was interested in a git bisect is that I suspect that > before nobody was interested in the request_queue in the aoe driver > until recent changes to kobject code. A couple people have indicated > that they'd be doing such a git bisect, so if anybody has done that, > please Cc me. > I finished bisecting the NULL object and ended up at this commit: cd43e26f071524647e660706b784ebcbefbd2e44 block: Expose stacked device queues in sysfs Currently stacking devices do not have a queue directory in sysfs. However, many of the I/O characteristics like sector size, maximum request size, etc. are queue properties. This patch enables the queue directory for MD/DM devices. The elevator code has been modified to deal with queues that do not have an I/O scheduler. Signed-off-by: Martin K. Petersen Signed-off-by: Jens Axboe This seems to generate /sys/block/$device/queue and its contents for everyone who is using queues, not just for those queues that have a non-NULL queue->request_fn. Bruno