Re: [PATCH] i386: PAE entries must have their low word cleared first

[Hugh Dickins]

On Wed, 26 Apr 2006, Keir Fraser wrote:
> 
> We cannot use pte_clear() unless we redefine it for PAE. Currently it reduces
> to set_pte() which explicitly uses the wrong ordering (sets high *then* low,
> because it's normally used to introduce a mapping).

I overlooked that reversal completely.  What a very good point.
I think that actually pte_clear() _does_ need to be redefined for PAE,
to reverse that ordering as you point out.  Take a look at its use in
mm/highmem.c (where a comment states it's safe against speculative
execution, but a comment can't guarantee that!): what do you think?

Hugh
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