Re: [SPARC32] NULL pointer derefference

[Mark Fortescue <mark@mtfhpc.demon.co.uk>]

>
> I feel like I ought to help out with this since it's my change which
> broke things, but I don't have access to a Sparc32 box.  Does anyone
> have a remotely rebootable machine I can use?
>
> Ollie
>

sun4c Sparc32 are probably a bit thin on the ground. Im my experience, 
they also have a habit of locking up (power up reset required) when 
debugging kernel issues.

However, I think I am getting somewhere.

The problem would apear to be that sun4c_update_mmu_cache is beeing called 
(either directly from the fault handling code or via update_mmu_cache) 
before the mm->context has been set up. The only place I found that sets 
this is sun4c_switch_mm (called from the scheduler as switch_mm).

In other words, the vma system is not operational untill after the task 
gets scheduled.

There may be a way around this - by calling sun4c_alloc_context when the 
mm gets set up. I will give it a go and see what happens.

David, are there any issues that you are aware of in calling 
sun4c_alloc_context without switching to it?

Regards
 	Mark Fortescue.

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