Re: Atomic operation for physically moving a page

[Dave Hansen]

On Fri, 2004-06-18 at 18:03, Valdis.Kletnieks@xxxxxx wrote:
> On Fri, 18 Jun 2004 17:37:12 PDT, Ashwin Rao <ashwin_s_rao@xxxxxxxxx>  said:
> > I want to copy a page from one physical location to
> > another (taking the appr. locks).
> 
> At the risk of sounding stupid, what problem are you trying to solve by copying
> a page? Not only (as you note) could the page be referenced by multiple
> processes, it could (conceivably) belong to a kernel slab or something, or be a
> buffer for an in-flight I/O request, or any number of other possibly-racy
> situations.

You also have to make sure that the page is something who's physical
address is allowed to change.  Some stuff like DMA buffers, or a part of
a hugetlb page might not even be valid to move.  

-- Dave

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