Re: [RFC] atomic pte updates and pae changes, take 2

From: Stephen Tweedie (
Date: Sat Oct 14 2000 - 08:33:09 EST


On Fri, Oct 13, 2000 at 08:17:42PM -0400, Ben LaHaise wrote:
> Below is take two of the patch making pte_clear use atomic xchg in an
> effort to avoid the loss of dirty bits. PAE no longer uses cmpxchg8 for
> updates; set_pte is two ordered long writes with a barrier.

Looks good. The only trouble I can see left is that pte_clear() is
still using set_pte(), which doesn't work right for PAE36. set_pte()
is setting the high word first, which is fine for installing a new pte,
but if you do that to clear a pte then you have left the old
page-present bit intact while you've removed have of the pte.
pte_clear() needs to clear the words in the other order (just as
pte_get_and_clear correctly does).

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