Re: mapping user space buffer to kernel address space

From: Linus Torvalds (torvalds@transmeta.com)
Date: Tue Oct 17 2000 - 16:04:10 EST


On Tue, 17 Oct 2000, Andrea Arcangeli wrote:
>
> IMHO pinning the page in the pte is less expensive and less complex than making
> rawio and the VM aware of those issues. (remap_page_range is so clean
> implementation exactly because it pins the page into the pte)

You keep on bringing up remap_page_range(), and it does nothing of the
sort.

remap_page_range() does one thing, and one thing only: it populates the
page tables with physical page mappings.

It has nothing to do with pinning.

It so happens that the vmscan stuff won't ever remove a physical page
mapping, but that's simply because such a page CANNOT be swapped out. How
would you swap out the PCI space?

I don't see why you consider that to have anything to do with kiobuf's.

                Linus

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