Subject: Re: can MEXTADD() storage be remapped ?
To: Jason Thorpe <>
From: Manuel Bouyer <>
List: tech-kern
Date: 05/24/2005 23:07:18
On Tue, May 24, 2005 at 10:45:13AM -0700, Jason Thorpe wrote:
> >it may still be effectively mapped). Flushing the pmap update queue  
> >from the
> >mbuf free routine cause problems (because it can be called from  
> >interrupt
> >context), and I could just skip this if I was sure that no additionnal
> >mapping ever existed for this buffer.
> Perhaps you could put in a DEBUG-only assertion that the queue is  
> empty.

The queue is shared for all non-urgent pmap updates (e.g. thoses that can wait
until the next context switch). I know it's not empty, because of the panic
I'm seeing. I could try to see if there are updates pending for this
PA, but this would mean making the queue updates interrupt-safe, which I'm
trying to avoid ...

> There should not be any other mappings for buffers that are  
> being ext_free'd.

Yes, what I'm trying to know if other mappings have ever existed (in which
case, their removal may still be in the queue).

Manuel Bouyer <>
     NetBSD: 26 ans d'experience feront toujours la difference