Hello, On Mon, Jun 11, 2018 at 06:29:20PM +0200, Jan Kara wrote: > > Would something like the following work or am I missing the point > > entirely? > > I was pondering the same solution for a while but I think it won't work. > The problem is that e.g. wb_memcg_offline() could have already removed > wb from the radix tree but it is still pending in bdi->wb_list > (wb_shutdown() has not run yet) and so we'd drop reference we didn't get. Yeah, right, so the root cause is that we're walking the wb_list while holding lock and expecting the object to stay there even after lock is released. Hmm... we can use a mutex to synchronize the two destruction paths. It's not like they're hot paths anyway. Thanks. -- tejun
