Index: sys/kern/vfs_vnops.c
===================================================================
--- sys/kern/vfs_vnops.c
+++ sys/kern/vfs_vnops.c
@@ -3519,6 +3519,8 @@
 				mp = NULL;
 			}
 		}
+		if (len != 0)
+			maybe_yield();
 	}
 out:
 	if (rl_cookie != NULL)