8b0f4e0a0d
to this pmap.c. This new r/w lock is used primarily to synchronize access to the PV lists. However, it will be used in a somewhat unconventional way. As finer-grained PV list locking is added to each of the pmap functions that acquire this r/w lock, its acquisition will be changed from write to read, enabling concurrent execution of the pmap functions with finer-grained locking. X-MFC after: r236045