On Tue, 2012-08-21 at 16:52 +0300, Michael S. Tsirkin wrote: > > + rcu_read_lock(); > > + mapping = rcu_dereference(page->mapping); > > + if (mapping_balloon(mapping)) > > + ret = true; > > + rcu_read_unlock(); > > This looks suspicious: you drop rcu_read_unlock > so can't page switch from balloon to non balloon? RCU read lock is a non-exclusive lock, it cannot avoid anything like that. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href