Re: crash by cdc_acm driver in kernels 4.8-rc1/5

From: Oliver Neukum
Date: Wed Sep 28 2016 - 11:23:46 EST


On Wed, 2016-09-28 at 17:08 +0200, Wim Osterholt wrote:
> On Wed, Sep 28, 2016 at 11:16:04AM +0200, Oliver Neukum wrote:
> > this should show you where it crashes. In addition I've attached
> > a patch with paranoid debugging. Could you compile and test a kernel
> > with it?
> >
> > Regards
> > Oliver
>
> If you mean
> echo "module cdc_acm +mpf" > /sys/kernel/debug/dynamic_debug/control
> etc, then it will take some time because I don't have the cabling not
> available now for a serial dump.
>
> Just 4.8-rc8 with the patched modules gave an oops of less than one screen
> while the machine stayed responsive long enough to grab it with the mouse
> and put it in a file:
>
> HP src # sync
> HP src # [ 3744.914184] BUG: unable to handle kernel NULL pointer dereference at 00000249

The last view lines before that please with the debugging level ramped
up to 9 please.

Regards
Oliver