/* * locking * * we have the following locks that we must contend with: * * mutexes: * * - pmap lock (per pmap, part of uvm_object) * this lock protects the fields in the pmap structure including * the non-kernel PDEs in the PDP, and the PTEs. it also locks * in the alternate PTE space (since that is determined by the * entry in the PDP). * * - pvh_lock (per pv_head) * this lock protects the pv_entry list which is chained off the * pv_head structure for a specific pv-tracked PA. it is locked * when traversing the list (e.g. adding/removing mappings, * syncing R/M bits, etc.) * * - pmaps_lock * this lock protects the list of active pmaps (headed by "pmaps"). * we lock it when adding or removing pmaps from this list. */