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SubjectRe: VM_RESERVED [was Re: mapping user space buffer to kernel address space]
Andrea Arcangeli wrote:
> > 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)

In any case, we shouldn't modify videodev.c to call vma_reserve()...
Let the driver's mmap operation do that or not do that, as it chooses.


Jeff Garzik | The difference between laziness and
Building 1024 | prioritization is the end result.
MandrakeSoft |
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