Continue the transition from synchronizing access to the page's PG_BUSY

flag and busy field with the global page queues lock to synchronizing their
access with the containing object's lock.  Specifically, acquire the
containing object's lock before reading the page's PG_BUSY flag and busy
field in vm_fault().

Reviewed by: tegge@

1 files changed, 29 insertions, 11 deletions

diff --git a/sys/vm/vm_fault.c b/sys/vm/vm_fault.c
index 4f6d1e9..69efea8 100644
--- a/sys/vm/vm_fault.c
+++ b/sys/vm/vm_fault.c
@@ -148,7 +148,7 @@ unlock_map(struct faultstate *fs)
 }
 
 static void
-_unlock_things(struct faultstate *fs, int dealloc)
+unlock_and_deallocate(struct faultstate *fs)
 {
 
 	vm_object_pip_wakeup(fs->object);
@@ -162,9 +162,7 @@ _unlock_things(struct faultstate *fs, int dealloc)
 		VM_OBJECT_UNLOCK(fs->first_object);
 		fs->first_m = NULL;
 	}
-	if (dealloc) {
-		vm_object_deallocate(fs->first_object);
-	}
+	vm_object_deallocate(fs->first_object);
 	unlock_map(fs);	
 	if (fs->vp != NULL) { 
 		mtx_lock(&Giant);
@@ -172,13 +170,10 @@ _unlock_things(struct faultstate *fs, int dealloc)
 		mtx_unlock(&Giant);
 		fs->vp = NULL;
 	}
-	if (dealloc && !fs->map->system_map)
+	if (!fs->map->system_map)
 		VM_UNLOCK_GIANT();
 }
 
-#define unlock_things(fs) _unlock_things(fs, 0)
-#define unlock_and_deallocate(fs) _unlock_things(fs, 1)
-
 /*
  * TRYPAGER - used by vm_fault to calculate whether the pager for the
  *	      current object *might* contain the page.
@@ -367,10 +362,33 @@ RetryFault:;
 			 */
 			if ((fs.m->flags & PG_BUSY) || fs.m->busy) {
 				vm_page_unlock_queues();
-				unlock_things(&fs);
-				vm_page_lock_queues();
-				if (!vm_page_sleep_if_busy(fs.m, TRUE, "vmpfw"))
+				VM_OBJECT_UNLOCK(fs.object);
+				if (fs.object != fs.first_object) {
+					VM_OBJECT_LOCK(fs.first_object);
+					vm_page_lock_queues();
+					vm_page_free(fs.first_m);
 					vm_page_unlock_queues();
+					vm_object_pip_wakeup(fs.first_object);
+					VM_OBJECT_UNLOCK(fs.first_object);
+					fs.first_m = NULL;
+				}
+				unlock_map(&fs);
+				if (fs.vp != NULL) {
+					mtx_lock(&Giant);
+					vput(fs.vp);
+					mtx_unlock(&Giant);
+					fs.vp = NULL;
+				}
+				VM_OBJECT_LOCK(fs.object);
+				if (fs.m == vm_page_lookup(fs.object,
+				    fs.pindex)) {
+					vm_page_lock_queues();
+					if (!vm_page_sleep_if_busy(fs.m, TRUE,
+					    "vmpfw"))
+						vm_page_unlock_queues();
+				}
+				vm_object_pip_wakeup(fs.object);
+				VM_OBJECT_UNLOCK(fs.object);
 				atomic_add_int(&cnt.v_intrans, 1);
 				if (!fs.map->system_map)
 					VM_UNLOCK_GIANT();