problematic because some callers to pmap_kextract() expect its
implementation to be lock-less. In particular, uma_dbg_alloc() implicitly
requires this. Otherwise, lock-order reversals occur between pmap locks and
UMA zone locks. So, this change introduces a lock-less implementation of
pmap_kextract().
Disable recursion on the pvh global lock in the new armv6 pmap. While
recursion on this locks occurs in the old arm pmap, it thankfully doesn't
occur in the armv6 pmap.
Tested by: jmg
703205f3c6