svn commit: r329156 - stable/11/sys/vm

[Konstantin Belousov]

Author: kib
Date: Mon Feb 12 10:34:15 2018
New Revision: 329156
URL: https://svnweb.freebsd.org/changeset/base/329156

Log:
  MFC r328880:
  On munlock(), unwire correct page.

Modified:
  stable/11/sys/vm/vm_object.c
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/vm/vm_object.c
==============================================================================
--- stable/11/sys/vm/vm_object.c	Mon Feb 12 06:52:49 2018	(r329155)
+++ stable/11/sys/vm/vm_object.c	Mon Feb 12 10:34:15 2018	(r329156)
@@ -2268,7 +2268,7 @@ void
 vm_object_unwire(vm_object_t object, vm_ooffset_t offset, vm_size_t length,
     uint8_t queue)
 {
-	vm_object_t tobject;
+	vm_object_t tobject, t1object;
 	vm_page_t m, tm;
 	vm_pindex_t end_pindex, pindex, tpindex;
 	int depth, locked_depth;
@@ -2282,6 +2282,7 @@ vm_object_unwire(vm_object_t object, vm_ooffset_t offs
 		return;
 	pindex = OFF_TO_IDX(offset);
 	end_pindex = pindex + atop(length);
+again:
 	locked_depth = 1;
 	VM_OBJECT_RLOCK(object);
 	m = vm_page_find_least(object, pindex);
@@ -2315,16 +2316,26 @@ vm_object_unwire(vm_object_t object, vm_ooffset_t offs
 			m = TAILQ_NEXT(m, listq);
 		}
 		vm_page_lock(tm);
+		if (vm_page_xbusied(tm)) {
+			for (tobject = object; locked_depth >= 1;
+			    locked_depth--) {
+				t1object = tobject->backing_object;
+				VM_OBJECT_RUNLOCK(tobject);
+				tobject = t1object;
+			}
+			vm_page_busy_sleep(tm, "unwbo", true);
+			goto again;
+		}
 		vm_page_unwire(tm, queue);
 		vm_page_unlock(tm);
 next_page:
 		pindex++;
 	}
 	/* Release the accumulated object locks. */
-	for (depth = 0; depth < locked_depth; depth++) {
-		tobject = object->backing_object;
-		VM_OBJECT_RUNLOCK(object);
-		object = tobject;
+	for (tobject = object; locked_depth >= 1; locked_depth--) {
+		t1object = tobject->backing_object;
+		VM_OBJECT_RUNLOCK(tobject);
+		tobject = t1object;
 	}
 }