longer create a pv entry for that mapping. (The two exceptions are
mappings into the kernel's exec and pipe submaps.) Consequently, there is
no reason for get_pv_entry() to dig deep into the free page queues, i.e.,
use VM_ALLOC_SYSTEM, by default. This revision changes get_pv_entry() to
use VM_ALLOC_NORMAL by default, i.e., before calling pmap_collect() to
reclaim pv entries.
Approved by: re (kensmith)
8beae25391