Re: serious issue caused by usb device, stalling almost all operations

On Monday 01 November 2010 15:38:38 Alexander Best wrote:
> On Mon Oct 25 10, Alexander Motin wrote:
> > Hans Petter Selasky wrote:
> > > On Wednesday 20 October 2010 17:30:40 Alexander Best wrote:
> > >> hi there,
> > >> 
> > >> i'm running HEAD (r213495; amd64). i stumbled upon this severe
> > >> problem:
> > >> 
> > >> after attaching my mobile phone, it simply resets without doing mount
> > >> or anything. however after letting the device come up again it won't
> > >> show up in the console. after detaching it the usb subsystem seemed
> > >> to have completely crashed. but that's not all. the following
> > >> programs now simply hang without producing any output C-C won't do
> > >> anything:
> > >> 
> > >> - dmesg
> > >> - top
> > >> - ps
> > >> - killall
> > >> - camcontrol devlist
> > >> - usbconfig
> > > 
> > > That's most likely because USB's umass driver is waiting for cam to
> > > drain. Possibly some refcounting is not correct. I suspect this is not
> > > a USB problem. Try to enter into the debugger, and look for backtrace
> > > for function stuck in umass_detach.
> 
> i set debug.kdb.panic=1, but didn't work, because writing the core dump
> stalled and watchdog came up.
> 

Maybe you could manually run:

bt all

And look for "cam" and "usb" keywords.

And write down the backtraces.

--HPS