On Tue 25-09-07 10:02:43, Peter Zijlstra wrote:
> On Mon, 3 Sep 2007 16:01:35 +0200 Jan Kara <[email protected]> wrote:
>
> > On Mon 03-09-07 05:49:59, Andrew Morton wrote:
> > > > On Mon, 3 Sep 2007 14:27:02 +0200 Jan Kara <[email protected]> wrote:
> > > > > > On Fri, 24 Aug 2007 23:00:33 +0200 Folkert van Heusden <[email protected]> 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 <[email protected]>
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 <[email protected]>
> ---
> 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 <[email protected]>
SUSE Labs, CR
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