Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757276AbXIYIZZ (ORCPT ); Tue, 25 Sep 2007 04:25:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754683AbXIYIZR (ORCPT ); Tue, 25 Sep 2007 04:25:17 -0400 Received: from styx.suse.cz ([82.119.242.94]:48447 "EHLO duck.suse.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1754600AbXIYIZP (ORCPT ); Tue, 25 Sep 2007 04:25:15 -0400 Date: Tue, 25 Sep 2007 10:46:30 +0200 From: Jan Kara To: Peter Zijlstra Cc: Andrew Morton , folkert@vanheusden.com, linux-kernel@vger.kernel.org Subject: Re: [2.6.22] circular lock detected Message-ID: <20070925084630.GA412@duck.suse.cz> References: <20070824210033.GB13237@vanheusden.com> <20070902045529.c66eddc9.akpm@linux-foundation.org> <20070903122702.GC29908@atrey.karlin.mff.cuni.cz> <20070903054959.3ecd9576.akpm@linux-foundation.org> <20070903140135.GE7524@duck.suse.cz> <20070925100243.2ceebd9e@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070925100243.2ceebd9e@twins> User-Agent: Mutt/1.5.13 (2006-08-11) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4531 Lines: 111 On Tue 25-09-07 10:02:43, Peter Zijlstra wrote: > On Mon, 3 Sep 2007 16:01:35 +0200 Jan Kara wrote: > > > On Mon 03-09-07 05:49:59, Andrew Morton wrote: > > > > On Mon, 3 Sep 2007 14:27:02 +0200 Jan Kara wrote: > > > > > > On Fri, 24 Aug 2007 23:00:33 +0200 Folkert van Heusden wrote: > > > > > > Has been reported before, but I don't recall whether we fixed it. Jan, > > > > > do you know>? > > > > I think we at least found a solution: Teach lockdep that I_MUTEX for > > > > different filesystems is different. Peter Zilstra wrote a patch for that > > > > and Folkert even confirmed that it fixes the problem for him. I'm not > > > > sure what happened with the patch afterwards though. Adding Peter to CC > > > > :). > > > > > > But this is a tty_lock-versus-dqptr_sem ranking error. Unrelated to i_mutex? > > The final report is for this ranking but the locking chain (if I understand it > > right) is: > > tty_mutex (con_close) -> i_mutex (sysfs: remove_subdir) > > i_mutex (do_truncate) -> i_alloc_sem (notify_change) -> truncate_mutex (ext3_truncate) > > truncate_mutex (ext3_get_blocks_handle) -> dqptr_sem (dquot_alloc_space) > > > > So it complains about tty_mutex vs dqptr_sem (I don't know why it does not > > complain about tty_mutex vs i_mutex) but the wrong link in the chain is > > that i_mutex from remove_subdir() [sysfs] and i_mutex from do_truncate() > > [ext3] are different and should never depend on each other... > > > > Found it again. Cool, thanks Peter. Andrew, would you put it into -mm? This should take care of the false lockdep warnings from the quota code. If I recall correctly, one of the reporters even confirmed it fixes the problem for him. The patch looks fine. You can add: Signed-off-by: Jan Kara Honza > Give each filesystem its own inode lock class. The various filesystems have > different locking order wrt the inode locks; esp. the pseudo filesystems > differ from the rest. > > Signed-off-by: Peter Zijlstra > --- > fs/inode.c | 12 +++++++++--- > include/linux/fs.h | 5 +++++ > 2 files changed, 14 insertions(+), 3 deletions(-) > > Index: linux-2.6/fs/inode.c > =================================================================== > --- linux-2.6.orig/fs/inode.c > +++ linux-2.6/fs/inode.c > @@ -142,6 +142,15 @@ static struct inode *alloc_inode(struct > return NULL; > } > > + spin_lock_init(&inode->i_lock); > + lockdep_set_class(&inode->i_lock, &sb->s_type->i_lock_key); > + > + mutex_init(&inode->i_mutex); > + lockdep_set_class(&inode->i_mutex, &sb->s_type->i_mutex_key); > + > + init_rwsem(&inode->i_alloc_sem); > + lockdep_set_class(&inode->i_alloc_sem, &sb->s_type->i_alloc_sem_key); > + > mapping->a_ops = &empty_aops; > mapping->host = inode; > mapping->flags = 0; > @@ -190,8 +199,6 @@ void inode_init_once(struct inode *inode > INIT_HLIST_NODE(&inode->i_hash); > INIT_LIST_HEAD(&inode->i_dentry); > INIT_LIST_HEAD(&inode->i_devices); > - mutex_init(&inode->i_mutex); > - init_rwsem(&inode->i_alloc_sem); > INIT_RADIX_TREE(&inode->i_data.page_tree, GFP_ATOMIC); > rwlock_init(&inode->i_data.tree_lock); > spin_lock_init(&inode->i_data.i_mmap_lock); > @@ -199,7 +206,6 @@ void inode_init_once(struct inode *inode > spin_lock_init(&inode->i_data.private_lock); > INIT_RAW_PRIO_TREE_ROOT(&inode->i_data.i_mmap); > INIT_LIST_HEAD(&inode->i_data.i_mmap_nonlinear); > - spin_lock_init(&inode->i_lock); > i_size_ordered_init(inode); > #ifdef CONFIG_INOTIFY > INIT_LIST_HEAD(&inode->inotify_watches); > Index: linux-2.6/include/linux/fs.h > =================================================================== > --- linux-2.6.orig/include/linux/fs.h > +++ linux-2.6/include/linux/fs.h > @@ -1302,8 +1302,13 @@ struct file_system_type { > struct module *owner; > struct file_system_type * next; > struct list_head fs_supers; > + > struct lock_class_key s_lock_key; > struct lock_class_key s_umount_key; > + > + struct lock_class_key i_lock_key; > + struct lock_class_key i_mutex_key; > + struct lock_class_key i_alloc_sem_key; > }; > > extern int get_sb_bdev(struct file_system_type *fs_type, > -- Jan Kara SUSE Labs, CR - 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/