On Mon, 2019-09-16 at 11:03 +0200, Sebastian Andrzej Siewior wrote: > On 2019-09-13 12:27:44 [-0400], Qian Cai wrote: > … > > Chain exists of: > > random_write_wait.lock --> &rq->lock --> batched_entropy_u32.lock > > > > Possible unsafe locking scenario: > > > > CPU0 CPU1 > > ---- ---- > > lock(batched_entropy_u32.lock); > > lock(&rq->lock); > > lock(batched_entropy_u32.lock); > > lock(random_write_wait.lock); > > would this deadlock still occur if lockdep knew that > batched_entropy_u32.lock on CPU0 could be acquired at the same time > as CPU1 acquired its batched_entropy_u32.lock? I suppose that might fix it too if it can teach the lockdep the trick, but it would be better if there is a patch if you have something in mind that could be tested to make sure.
