Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932121AbWHUAVn (ORCPT ); Sun, 20 Aug 2006 20:21:43 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932130AbWHUAVn (ORCPT ); Sun, 20 Aug 2006 20:21:43 -0400 Received: from cantor2.suse.de ([195.135.220.15]:28393 "EHLO mx2.suse.de") by vger.kernel.org with ESMTP id S932121AbWHUAVm (ORCPT ); Sun, 20 Aug 2006 20:21:42 -0400 From: Neil Brown To: Peter Zijlstra Date: Mon, 21 Aug 2006 10:21:27 +1000 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <17640.64647.311004.869344@cse.unsw.edu.au> Cc: Rolf Eike Beer , linux-kernel@vger.kernel.org, Ingo Molnar , Arjan van de Ven , Andrew Morton Subject: Re: [BUG?] possible recursive locking detected (blkdev_open) In-Reply-To: message from Peter Zijlstra on Friday August 18 References: <200608090757.32006.eike-kernel@sf-tec.de> <1155897321.5696.374.camel@twins> X-Mailer: VM 7.19 under Emacs 21.4.1 X-face: [Gw_3E*Gng}4rRrKRYotwlE?.2|**#s9D > blkdev_open() calls > do_open(bdev, ...,BD_MUTEX_NORMAL) and takes > mutex_lock_nested(&bdev->bd_mutex, BD_MUTEX_NORMAL) > > then something fails, and we're thrown to: > > out_first: where > if (bdev != bdev->bd_contains) > blkdev_put(bdev->bd_contains) which is > __blkdev_put(bdev->bd_contains, BD_MUTEX_NORMAL) which does > mutex_lock_nested(&bdev->bd_contains->bd_mutex, BD_MUTEX_NORMAL) <--- lockdep trigger > > When going to out_first, dbev->bd_contains is either bdev or whole, and > since we take the branch it must be whole. So it seems to me the > following patch would be the right one: Looks sensible to me. > > Signed-off-by: Peter Zijlstra Acked-by: NeilBrown NeilBrown > --- > fs/block_dev.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > Index: linux-2.6/fs/block_dev.c > =================================================================== > --- linux-2.6.orig/fs/block_dev.c > +++ linux-2.6/fs/block_dev.c > @@ -980,7 +980,7 @@ out_first: > bdev->bd_disk = NULL; > bdev->bd_inode->i_data.backing_dev_info = &default_backing_dev_info; > if (bdev != bdev->bd_contains) > - blkdev_put(bdev->bd_contains); > + __blkdev_put(bdev->bd_contains, BD_MUTEX_WHOLE); > bdev->bd_contains = NULL; > put_disk(disk); > module_put(owner); > > > > > > - > 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/ - 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/