On Tue, Jul 30, 2019 at 11:17:56AM -0700, Bart Van Assche wrote: > It is required to protect blkg_lookup() calls with a blk_queue_enter() / > blk_queue_exit() pair. Since it is nontrivial to verify whether this is Could you explain the reason why the blk_queue_enter()/blk_queue_exit() pair is required for blkg_lookup()? And comment on blkg_lookup() only mentioned RCU read lock is needed. The request queue reference counter is supposed to be held for any caller of submit_bio(), why isn't that ref count enough? Thanks, Ming
