Mark Johnston ae00e67228 Reuse the PV entry when updating a mapping in pmap_enter().
This addresses a problem described in r335784, where memory
pressure forces reclamation of a PV chunk and in rare cases leads to a
use-after-free of a page table page.

Reviewed by:	alc, kib
MFC after:	3 weeks
Differential Revision:	https://reviews.freebsd.org/D16181
2018-07-08 20:38:46 +00:00
..