Fix locking violations during page wiring:

 - vm map entries are not valid after the map has been unlocked.

 - An exclusive lock on the map is needed before calling
   vm_map_simplify_entry().

Fix cleanup after page wiring failure to unwire all pages that had been
successfully wired before the failure was detected.

Reviewed by:	dillon

1 files changed, 32 insertions, 3 deletions

diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c
index 895775b5..9bbe14b 100644
--- a/sys/vm/vm_map.c
+++ b/sys/vm/vm_map.c
@@ -1412,6 +1412,7 @@ vm_map_user_pageable(
 	vm_map_entry_t entry;
 	vm_map_entry_t start_entry;
 	vm_offset_t estart;
+	vm_offset_t eend;
 	int rv;
 
 	vm_map_lock(map);
@@ -1489,6 +1490,7 @@ vm_map_user_pageable(
 			entry->wired_count++;
 			entry->eflags |= MAP_ENTRY_USER_WIRED;
 			estart = entry->start;
+			eend = entry->end;
 
 			/* First we need to allow map modifications */
 			vm_map_set_recursive(map);
@@ -1503,8 +1505,15 @@ vm_map_user_pageable(
 
 				vm_map_clear_recursive(map);
 				vm_map_unlock(map);
-				
-				(void) vm_map_user_pageable(map, start, entry->start, TRUE);
+			
+				/*
+				 * At this point, the map is unlocked, and
+				 * entry might no longer be valid.  Use copy
+				 * of entry start value obtained while entry
+				 * was valid.
+				 */
+				(void) vm_map_user_pageable(map, start, estart,
+							    TRUE);
 				return rv;
 			}
 
@@ -1514,9 +1523,15 @@ vm_map_user_pageable(
 				if (vm_map_lookup_entry(map, estart, &entry) 
 				    == FALSE) {
 					vm_map_unlock(map);
+					/* 
+					 * vm_fault_user_wire succeded, thus
+					 * the area between start and eend
+					 * is wired and has to be unwired
+					 * here as part of the cleanup.
+					 */
 					(void) vm_map_user_pageable(map,
 								    start,
-								    estart,
+								    eend,
 								    TRUE);
 					return (KERN_INVALID_ADDRESS);
 				}
@@ -1753,6 +1768,20 @@ vm_map_pageable(
 			(void) vm_map_pageable(map, start, failed, TRUE);
 			return (rv);
 		}
+		/*
+		 * An exclusive lock on the map is needed in order to call
+		 * vm_map_simplify_entry().  If the current lock on the map
+		 * is only a shared lock, an upgrade is needed.
+		 */
+		if (vm_map_pmap(map) != kernel_pmap &&
+		    vm_map_lock_upgrade(map)) {
+			vm_map_lock(map);
+			if (vm_map_lookup_entry(map, start, &start_entry) ==
+			    FALSE) {
+				vm_map_unlock(map);
+				return KERN_SUCCESS;
+			}
+		}
 		vm_map_simplify_entry(map, start_entry);
 	}