On (08/23/17 09:03), Byungchul Park wrote: [..] aha, ok > The report is talking about the following lockup: > > A work in a worker A task work on exit to user > ------------------ --------------------------- > mutex_lock(&bdev->bd_mutex) > mutext_lock(&bdev->bd_mutex) > blk_execute_rq() > wait_for_completion_io_timeout(&A) > complete(&A) > > Is this impossible? I was really confused how this "unlock" may lead to a deadlock > > > other info that might help us debug this: > > > Possible unsafe locking scenario by crosslock: > > > CPU0 CPU1 > > > ---- ---- > > > lock(&bdev->bd_mutex); > > > lock((complete)&wait#2); > > > lock(&bdev->bd_mutex); > > > unlock((complete)&wait#2); any chance the report can be improved? mention timeout, etc? // well, if this functionality will stay. p.s. Bart Van Assche, thanks for Cc-ing Park Byungchul, I was really sure I didn't enabled the cross-release, but apparently I was wrong: CONFIG_LOCKDEP_CROSSRELEASE=y CONFIG_LOCKDEP_COMPLETIONS=y -ss
