Re: 2.5.8-pre3: kernel BUG at usb.c:849! (preempt_count 1)

[Duncan Sands]

On Wednesday 10 April 2002 5:41 pm, you wrote:
> On Wed, Apr 10, 2002, Duncan Sands <[e-mail]> wrote:
> > UP x86 K6 system running 2.5.8-pre3 with preemption.
> > Using usb-uhci.  I got the following bug when powering off:
> >
> > usb.c: USB disconnect on device 3
> > kernel BUG at usb.c:849!
> > invalid operand: 0000
> > CPU:    0
> > EIP:    0010:[<cc8babe2>]    Not tainted
> > EFLAGS: 00010246
> > eax: 00000000   ebx: cb8e2800   ecx: cb8e2550   edx: 00000002
> > esi: cbc75d88   edi: cc8c7a20   ebp: ffffffff   esp: cab5ff24
> > ds: 0018   es: 0018   ss: 0018
> > Process rmmod (pid: 1787, threadinfo=cab5e000 task=c952a6a0)
> > Stack: cb8e29f8 cc8bbafe cb8e2800 cb8e25bc cb796180 cc8c79a0 0000000e
> > 0000024c cb8e2800 cc8bbaad cb8e25bc cb796080 cc8ce600 c71a5000 cc8c9000
> > 000000c4 cb8e2400 cc8ccc7a cab5ff74 c12dc800 00000000 c01cf07f c12dc800
> > cc8c9000 Call Trace: [<cc8bbafe>] [<cc8c79a0>] [<cc8bbaad>] [<cc8ce600>]
> > [<cc8ccc7a>] [pci_unregister_driver+51/76] [<cc8cd176>] [<cc8ce600>]
> > [free_module+23/192] [sys_delete_module+292/628] [syscall_call+7/11]
> > Code: 0f 0b 51 03 94 42 8c cc 8b 83 cc 00 00 00 8b 40 18 53 8b 40
>
> Could you run this through ksymoops?

I did but it didn't give any more info.  The problem is that I had no
 /var/log/ksymoops directory (used for automatic dumping of symbol info), so
 after the reboot I couldn't tell ksymoops where the modules were loaded... 
 I am now trying to reproduce the oops and get more info.

> >  <3>error: rmmod[1787] exited with preempt_count 1
>
> I don't like the looks of that.
>
> JE

It suggests a locking problem, but it may be misleading: imagine the oops
came when a spin lock was held, then couldn't you get this message?

All the best,

Duncan.