From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757699Ab0LHCE5 (ORCPT ); Tue, 7 Dec 2010 21:04:57 -0500 Received: from kroah.org ([198.145.64.141]:48276 "EHLO coco.kroah.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756726Ab0LHA66 (ORCPT ); Tue, 7 Dec 2010 19:58:58 -0500 X-Mailbox-Line: From gregkh@clark.site Tue Dec 7 16:57:21 2010 Message-Id: <20101208005721.652865552@clark.site> User-Agent: quilt/0.48-11.2 Date: Tue, 07 Dec 2010 16:56:19 -0800 From: Greg KH To: linux-kernel@vger.kernel.org, stable@kernel.org Cc: stable-review@kernel.org, torvalds@linux-foundation.org, akpm@linux-foundation.org, alan@lxorguk.ukuu.org.uk, Jan Kara , Jens Axboe Subject: [002/289] block: Fix race during disk initialization In-Reply-To: <20101208005821.GA2922@kroah.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 2.6.36-stable review patch. If anyone has any objections, please let us know. ------------------ From: Jan Kara commit 01ea50638bc04ca5259f5711fcdedefcdde1cf43 upstream. When a new disk is being discovered, add_disk() first ties the bdev to gendisk (via register_disk()->blkdev_get()) and only after that calls bdi_register_bdev(). Because register_disk() also creates disk's kobject, it can happen that userspace manages to open and modify the device's data (or inode) before its BDI is properly initialized leading to a warning in __mark_inode_dirty(). Fix the problem by registering BDI early enough. This patch addresses https://bugzilla.kernel.org/show_bug.cgi?id=16312 Reported-by: Larry Finger Signed-off-by: Jan Kara Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- block/genhd.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/block/genhd.c +++ b/block/genhd.c @@ -541,13 +541,15 @@ void add_disk(struct gendisk *disk) disk->major = MAJOR(devt); disk->first_minor = MINOR(devt); + /* Register BDI before referencing it from bdev */ + bdi = &disk->queue->backing_dev_info; + bdi_register_dev(bdi, disk_devt(disk)); + blk_register_region(disk_devt(disk), disk->minors, NULL, exact_match, exact_lock, disk); register_disk(disk); blk_register_queue(disk); - bdi = &disk->queue->backing_dev_info; - bdi_register_dev(bdi, disk_devt(disk)); retval = sysfs_create_link(&disk_to_dev(disk)->kobj, &bdi->dev->kobj, "bdi"); WARN_ON(retval);