Author: kib
Date: Thu May 20 08:51:01 2010
New Revision: 208340
URL: http://svn.freebsd.org/changeset/base/208340

Log:
  When waiting for the busy page, do not unlock the object unless unlock
  cannot be avoided.
  
  Reviewed by:  alc
  MFC after:    1 week

Modified:
  head/sys/vm/vm_fault.c

Modified: head/sys/vm/vm_fault.c
==============================================================================
--- head/sys/vm/vm_fault.c      Thu May 20 08:43:31 2010        (r208339)
+++ head/sys/vm/vm_fault.c      Thu May 20 08:51:01 2010        (r208340)
@@ -340,9 +340,13 @@ RetryFault:;
                                vm_page_flag_set(fs.m, PG_REFERENCED);
                                vm_page_unlock_queues();
                                vm_page_unlock(fs.m);
-                               VM_OBJECT_UNLOCK(fs.object);
                                if (fs.object != fs.first_object) {
-                                       VM_OBJECT_LOCK(fs.first_object);
+                                       if (!VM_OBJECT_TRYLOCK(
+                                           fs.first_object)) {
+                                               VM_OBJECT_UNLOCK(fs.object);
+                                               VM_OBJECT_LOCK(fs.first_object);
+                                               VM_OBJECT_LOCK(fs.object);
+                                       }
                                        vm_page_lock(fs.first_m);
                                        vm_page_free(fs.first_m);
                                        vm_page_unlock(fs.first_m);
@@ -351,7 +355,6 @@ RetryFault:;
                                        fs.first_m = NULL;
                                }
                                unlock_map(&fs);
-                               VM_OBJECT_LOCK(fs.object);
                                if (fs.m == vm_page_lookup(fs.object,
                                    fs.pindex)) {
                                        vm_page_sleep_if_busy(fs.m, TRUE,
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