Re: VM_RESERVED [was Re: mapping user space buffer to kernel address space]

[Andrea Arcangeli]

On Fri, Oct 20, 2000 at 10:10:05AM -0700, Linus Torvalds wrote:
> Sure. I have no problem at all with this suggestion: it's basically just a
> hint to the VM layer that trying to page something out in this vma is
> useless, as its backing store is in memory anyway.

Yes, that is _exactly_ the point.

> As to your rvmalloc()/rvfree() changes, I don't think they are safe as-is:
> I think it's the right thing to do, but I don't trust the drivers to
> maintain the right page counts. The code used to mark the pages as
> reserved, which probably means that it hides bad drivers that do not do
> proper reference counting - and I'm not willing to make that kind of
> change at this point.

The page count of the mapped pages should be ok, it seems those mapped pages
have a reference count of 1 just from the vmalloc allocation and they use
PG_reserved just to skip swap_out, but I feel safer too if the bttv maintainers
will check it and send it to you themself after checking it's correct. (I only
verified that it was compiling correctly)

Thanks.

Andrea
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