From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752739Ab2A0GDq (ORCPT ); Fri, 27 Jan 2012 01:03:46 -0500 Received: from nat28.tlf.novell.com ([130.57.49.28]:49262 "EHLO nat28.tlf.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751353Ab2A0GDp (ORCPT ); Fri, 27 Jan 2012 01:03:45 -0500 Message-ID: <4F223E2F.8070907@suse.com> Date: Fri, 27 Jan 2012 11:33:27 +0530 From: Suresh Jayaraman User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.24) Gecko/20111101 SUSE/3.1.16 Thunderbird/3.1.16 MIME-Version: 1.0 To: Vivek Goyal CC: Tejun Heo , LKML , Jens Axboe , Dirk Gouders Subject: Re: Slab corruption in floppy driver module References: <4F1EAFE9.5000306@suse.com> <20120124223153.GG17291@redhat.com> <20120126150420.GD1891@redhat.com> <20120126180532.GA4077@dhcp-172-17-108-109.mtv.corp.google.com> <20120126193735.GA11297@redhat.com> In-Reply-To: <20120126193735.GA11297@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/27/2012 01:07 AM, Vivek Goyal wrote: > On Thu, Jan 26, 2012 at 10:05:32AM -0800, Tejun Heo wrote: >> >> Yeah, this looks correct to me. It might be better to tone down the >> comment a bit tho. Wouldn't it be sufficient to say put_disk() isn't >> paired with add_disk() and will put one extra time? > > Sure. Toned down the comment as suggested. Here is the new patch. > > floppy: Cleanup disk->queue before caling put_disk() if add_disk() was never called > > add_disk() takes gendisk reference on request queue. If driver failed during > initialization and never called add_disk() then that extra reference is not > taken. That reference is put in put_disk(). floppy driver allocates the > disk, allocates queue, sets disk->queue and then relizes that floppy > controller is not present. It tries to tear down everything and tries to > put a reference down in put_disk() which was never taken. > > In such error cases cleanup disk->queue before calling put_disk() so that > we never try to put down a reference which was never taken in first place. > > Reported-by: Suresh Jayaraman > Tested-by: Dirk Gouders > Signed-off-by: Vivek Goyal > --- > drivers/block/floppy.c | 8 +++++++- > 1 file changed, 7 insertions(+), 1 deletion(-) > > Index: linux-2.6/drivers/block/floppy.c > =================================================================== > --- linux-2.6.orig/drivers/block/floppy.c 2012-01-15 09:49:14.000000000 -0500 > +++ linux-2.6/drivers/block/floppy.c 2012-01-26 14:35:14.662374464 -0500 > @@ -4368,8 +4368,14 @@ out_unreg_blkdev: > out_put_disk: > while (dr--) { > del_timer_sync(&motor_off_timer[dr]); > - if (disks[dr]->queue) > + if (disks[dr]->queue) { > blk_cleanup_queue(disks[dr]->queue); > + /* > + * put_disk() is not paired with add_disk() and > + * will put queue reference one extra time. fix it. > + */ > + disks[dr]->queue = NULL; > + } > put_disk(disks[dr]); > } > return err; > Thanks. With this patch I'm no longer seeing the slab corruption or Oops which was seen earlier. Reported-and-Tested-by: Suresh Jayaraman OTOH, is there a small chance that this problem pattern being present (waiting to be discovered) in other block devices as well... So far haven't found anything during a quick auditing.