On Sun, Jun 10, 2018 at 11:47:56PM +0900, Tetsuo Handa wrote: > This looks quite strange that nobody is holding percpu_rw_semaphore for > write but everybody is stuck trying to hold it for read. (Since there > is no "X locks held by ..." line without followup "#0:" line, there is > no possibility that somebody is in TASK_RUNNING state while holding > percpu_rw_semaphore for write.) > > I feel that either API has a bug or API usage is wrong. > Any idea for debugging this?
Look at percpu_rwsem_release() and usage. The whole fs freezer thing is magic.
