[i2c] [crash, bisected] I2C, kobject (ffff81003e8c4160): tried to init an initialized object

[Alexey Dobriyan]

On Thu, Jul 17, 2008 at 11:33:30AM +0200, Ingo Molnar wrote:
> 
> * Ingo Molnar <mingo at elte.hu> wrote:
> 
> > Jean,
> > 
> > -tip testing found another (similar) i2c crash with latest -git, on a 
> > Core2Duo laptop:
> > 
> > calling  nforce2_init+0x0/0x1b
> > initcall nforce2_init+0x0/0x1b returned 0 after 0 msecs
> > calling  nforce2_s4985_init+0x0/0x275
> > BUG: unable to handle kernel NULL pointer dereference at 0000000c
> > IP: [<c04af2cf>] i2c_smbus_xfer+0x27/0x3f0
> > *pdpt = 00000000009cb001 *pde = 0000000000000000 
> > Oops: 0000 [#1] SMP 
> 
> turning off I2C_NFORCE2_S4985 makes the system boot up fine. Workaround 
> patch below.

Well, it's pretty easy oops unless I misread something.

It happened on not nforce2 motherboard, right?

nforce2_init will just register PCI driver,
no matching PCI ids => nforce2_set_reference() isn't called =>
nforce2_smbus stays NULL.

Second module loads and tries to i2c_smbus_xfer(NULL, ) in module_init()
hook which oopses.