Re: question on symbol exports

Arjan van de Ven
2005-02-01T15:51:06Z

On Tue, 2005-02-01 at 09:37 -0600, Chris Friesen wrote:
> Arjan van de Ven wrote:
> > On Mon, 2005-01-31 at 18:15 -0600, Chris Friesen wrote:
>
> >>Is there any particular reason why modules should not be allowed to
> >>flush the tlb, or is this an oversight?
> >
> > can you point at the url to your module source? I suspect modules doing
> > tlb flushes is the wrong thing, but without seeing the source it's hard
> > to tell.
>
> I've included the relevent code at the bottom. The module will be
> released under the GPL.
>
> I've got a module that I'm porting forward from 2.4. The basic idea is
> that we want to be able to track pages dirtied by an application. The
> system has no swap, so we use the dirty bit to get this information. On
> demand we walk the page tables belonging to the process, store the
> addresses of any dirty ones, flush the tlb, and mark them clean.

afaik one doesn't need to do a tlb flush in code that clears the dirty
bit, as long as you use the proper vm functions to do so.
(if those need a tlb flush, those are supposed to do that for you
afaik).

Also note that your code isn't dealing with 4 level pagetables.... And
pagetable walking in drivers is basically almost always a mistake and a
sign that something is wrong.