On Thu, 19 Oct 2006, Helge Hafting wrote:
> Alan Stern wrote:
> > On Wed, 18 Oct 2006, Helge Hafting wrote:
> >
> [...]
> > That's why I asked for the USB debugging logs (which you forgot to include
> > here).
> >
> Attached dmesg.gz with lots of usb messages.
But no messages from the time just before the BUG occurred. :-(
> >> To bring it down:
> >>
> >> dd if=/dev/sdc of=sdc.dump bs=1M
> >>
> This time, it seems to have crashed on the first megabyte.
> I mounted the filesystem synchronously, and still I had 0 bytes
> in the dumpfile. The crash also came with no delay after
> pressing enter.
>
> > It's possible that both of these are caused by something unrelated
> > overwriting kernel memory.
> >
> something like a function pointer mistaken for a data pointer?
After looking at the debugging output, no. That "invalid opcode" is a red
herring. What you encountered this time was a BUG() in the source code of
start_unlink_async() in drivers/usb/host/ehci-q.c:
#ifdef DEBUG
assert_spin_locked(&ehci->lock);
if (ehci->reclaim
|| (qh->qh_state != QH_STATE_LINKED
&& qh->qh_state != QH_STATE_UNLINK_WAIT)
)
BUG ();
#endif
You could try putting a printk() just before the BUG() to display the
values of ehci->reclaim and qh->qh_state. Maybe also change the BUG() to
WARN(), which might help prevent your system from crashing so badly.
Monty has been making changes to this driver recently; maybe he has some
ideas about the problem.
Alan Stern
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