Re: [Bluez-devel] Soft lockup

[Marcel Holtmann <marcel@holtmann.org>]

Hi Bastien,

> > > Now I have more information about this problem.
> > > 
> > > I had debuggin enabled in net/bluetooth/rfcomm/core.c and I noticed that
> > > for some reson rfcomm_dlc_clear_timer() is called for allready freed
> > > dlc and lock_timer_base() gets stuck because it's trying to use invalid
> > > timer pointer. I also tried to reproduce bug in i386 without success.
> > > Also then debugging is on the bug much harder to reproduse. To me this
> > > looks like dlc locking doens't work as it should work.
> > > 
> > > And other notice. rfcomm_dlc_clear_timeri() uses timer_pending()
> > > together with del_timer() which allready calls timer_pending(). So
> > > timer_pending() is useless in rfcomm_dlc_clear_timer().
> > 
> > this all looks like we are missing a memory barrier somewhere. This
> > could also be the reason why it only gets triggered on OMAP systems. Any
> > further ideas?
> 
> I'm getting the same kind of trace (on both x86-64 and i386) when
> testing the gnome-vfs2-obexftp package with a patch to use the new
> serial service[1].
> 
> It happens on 2.6.19-1.2895.fc6 (x86-64) and 2.6.21-1.3191.fc7 (i386).
> 
> Here's what I could capture from the i386 crash:
> BUG warning at lib/kref.c:32/kref_get()

any chance you can test a 2.6.22-rc3 kernel. We fixed some potential
problems in RFCOMM and Greg pushed some driver model changes that might
make this go away. I really have no idea what triggers this at the
moment. However I would like to see a simple reproducer.

Regards

Marcel



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