On Wednesday, May 21, 2003, at 04:44  PM, Stephan Uphoff wrote:

> pmap_enter() does not replace the old mapping atomically with the new 
> mapping
>              if the old mapping points to a managed page.
> 	     Other CPUs might observe va to be unmapped (pte == 0) before
>              pmap_enter sets the new mapping.
>
> 	     I don't think this is a problem.
>              If it is, the pve handling needs to be changed.

I don't think it's a problem, either.  In this case, the worst that 
could happen is that the other CPU would take a page fault, but then 
would block in the upper layers of the VM code.  By the time it 
unblocked, the only damage it could do would be to enter the same 
mapping again.

         -- Jason R. Thorpe <thorpej@wasabisystems.com>