ppc64 oops..

[Hugh Dickins]

On Tue, 15 Nov 2005, Linus Torvalds wrote:
> 
> So this was a purely ppc64 bug, not a VM one.

But you're right to be concerned about the loss of that PG_reserved
safety net for initial kernel memory.  Like Nick, I would like to do
away with it in the long term; but the kind of bugs we're seeing at
the moment, whether or not they turn out to be caused by those changes,
we do want the safety net back, with a warning to tell when it's being
used (and not clearing PG_reserved in bad_page, but preventing the
page being reused).  After a couple of silent releases we can discuss
whether to throw the net away; but it's been silently working for so
long, we've no idea how much might be relying on it.

Hugh