Re: [Bugme-new] [Bug 2019] New: Bug from the mm subsystem involving X (fwd)

[Linus Torvalds <torvalds@osdl.org>]

On Wed, 4 Feb 2004, Keith Mannthey wrote:
> 
> Martin sent me a patch that fixed the X panics (NUMA and DISCONTIG
> enabled).  (Thanks Martin!) I don't have the same X panics and issues I
> had before. I don't know if this will work for the generic case. It
> compiles with a simple memory situation just fine but I didn't boot it. 

Looks ok, but the thing should be made a function (possibly inline, 
depending on how big the code generated ends up being). As it is, it now 
uses its arguments several times, and while I don't see anything where 
that could screw up, it's just a tad scary.

Also, related to this whole mess, what the _heck_ is this in mm/rmap.c:

        if (!pfn_valid(page_to_pfn(page)) || PageReserved(page))
                return pte_chain;

that "pfn_valid(page_to_pfn(page))" just looks totally nonsensical. Can
somebody really pass in random page pointers to this thing, and if so, are
they guaranteed to be "not-random enough" to not cause bogus behaviour
when the "page_to_pfn()" happens to be valid..

If VM_IO gets rid of this, then we should immediately apply the patch.

			Linus
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