kernel - Fix edge case with machdep.pmap_mmu_optimize on x86-64

* Fix two edge cases when enabling or disabling machdep.pmap_mmu_optimize,
  causing a shared page table page to be reverted to a local page table page
  and vise-versa.

* Remove debugging kprintf()s

Reported-by: thesjg

diff --git a/sys/platform/pc64/x86_64/pmap.c b/sys/platform/pc64/x86_64/pmap.c
index 551816f..0f6a248 100644 (file)
--- a/sys/platform/pc64/x86_64/pmap.c
+++ b/sys/platform/pc64/x86_64/pmap.c
@@ -1635,8 +1635,6 @@ pmap_allocpte(pmap_t pmap, vm_pindex_t ptepindex, pv_entry_t *pvpp)
                        pt_entry_t pte;
                        pmap_inval_info info;
 
-                       kprintf("pmap_allocpte: restate shared pg table pg\n");
-
                        if (ispt == 0) {
                                panic("pmap_allocpte: unexpected pte %p/%d",
                                      pvp, (int)ptepindex);
@@ -1646,8 +1644,12 @@ pmap_allocpte(pmap_t pmap, vm_pindex_t ptepindex, pv_entry_t *pvpp)
                        pte = pte_load_clear(ptep);
                        pmap_inval_deinterlock(&info, pmap);
                        pmap_inval_done(&info);
-                       if (vm_page_unwire_quick(PHYS_TO_VM_PAGE(pte & PG_FRAME)))
-                               panic("pmap_allocpte: shared pgtable pg bad wirecount");
+                       if (vm_page_unwire_quick(
+                                       PHYS_TO_VM_PAGE(pte & PG_FRAME))) {
+                               panic("pmap_allocpte: shared pgtable "
+                                     "pg bad wirecount");
+                       }
+                       atomic_add_long(&pmap->pm_stats.resident_count, -1);
                } else {
                        vm_page_wire_quick(pvp->pv_m);
                }
@@ -1697,6 +1699,7 @@ pmap_allocpte_seg(pmap_t pmap, vm_pindex_t ptepindex, pv_entry_t *pvpp,
        pd_entry_t npte;        /* contents of *pt */
        vm_page_t m;
 
+retry:
        /*
         * Basic tests, require a non-NULL vm_map_entry, require proper
         * alignment and type for the vm_map_entry, require that the
@@ -1805,10 +1808,22 @@ pmap_allocpte_seg(pmap_t pmap, vm_pindex_t ptepindex, pv_entry_t *pvpp,
               (PG_U | PG_RW | PG_V | PG_A | PG_M);
 
        /*
-        * Dispose of previous entry if it was local to the process pmap.
-        * (This should zero-out *pt)
+        * Dispose of previous page table page if it was local to the
+        * process pmap.  If the old pt is not empty we cannot dispose of it
+        * until we clean it out.  This case should not arise very often so
+        * it is not optimized.
         */
        if (proc_pt_pv) {
+               if (proc_pt_pv->pv_m->wire_count != 1) {
+                       pv_put(proc_pd_pv);
+                       pv_put(proc_pt_pv);
+                       pv_put(pt_pv);
+                       pv_put(pte_pv);
+                       pmap_remove(pmap,
+                                   va & ~(vm_offset_t)SEG_MASK,
+                                   (va + SEG_SIZE) & ~(vm_offset_t)SEG_MASK);
+                       goto retry;
+               }
                pmap_release_pv(proc_pt_pv, proc_pd_pv);
                proc_pt_pv = NULL;
                /* relookup */
@@ -4639,8 +4654,6 @@ pmap_object_free(vm_object_t object)
 
        if ((pmap = object->md.pmap_rw) != NULL) {
                object->md.pmap_rw = NULL;
-               kprintf("pmap_object_free: destroying pmap %p in obj %p\n",
-                       pmap, object);
                pmap_remove_noinval(pmap,
                                  VM_MIN_USER_ADDRESS, VM_MAX_USER_ADDRESS);
                pmap->pm_active = 0;
@@ -4650,8 +4663,6 @@ pmap_object_free(vm_object_t object)
        }
        if ((pmap = object->md.pmap_ro) != NULL) {
                object->md.pmap_ro = NULL;
-               kprintf("pmap_object_free: destroying pmap %p in obj %p\n",
-                       pmap, object);
                pmap_remove_noinval(pmap,
                                  VM_MIN_USER_ADDRESS, VM_MAX_USER_ADDRESS);
                pmap->pm_active = 0;