Re: bd_mount_mutex -> bd_mount_sem (was Re: xfs_file_ioctl / xfs_freeze: BUG: warning at kernel/mutex-debug.c:80/debug_mutex_unlock())

[Andrew Morton <akpm@xxxxxxxx>]

On Mon, 08 Jan 2007 21:12:40 -0600
Eric Sandeen <sandeen@xxxxxxxxxxx> wrote:

> Andrew Morton wrote:
> > On Tue, 9 Jan 2007 10:47:28 +1100
> > David Chinner <dgc@xxxxxxx> wrote:
> > 
> >> On Mon, Jan 08, 2007 at 10:40:54AM -0600, Eric Sandeen wrote:
> >>> Sami Farin wrote:
> >>>> On Mon, Jan 08, 2007 at 08:37:34 +1100, David Chinner wrote:
> >>>> ...
> >>>>>> fstab was there just fine after -u.
> >>>>> Oh, that still hasn't been fixed?
> >>>> Looked like it =)
> >>> Hm, it was proposed upstream a while ago:
> >>>
> >>> http://lkml.org/lkml/2006/9/27/137
> >>>
> >>> I guess it got lost?
> >> Seems like it. Andrew, did this ever get queued for merge?
> > 
> > Seems not.  I think people were hoping that various nasties in there
> > would go away.  We return to userspace with a kernel lock held??
> 
> Is a semaphore any worse than the current mutex in this respect?  At 
> least unlocking from another thread doesn't violate semaphore rules.  :)

I assume that if we weren't returning to userspace with a lock held, this
mutex problem would simply go away.