lctl thread was sleeping and waiting lock to be granted
The wait is infinite.
Here is four clients which conflicts with lock
It looks like problem started from a network errors
MGC uses OBD_CONNECT_MNE_SWAB flag.
The root cause of this problem is flag OBD_CONNECT_MNE_SWAB equal to OBD_CONNECT_MDS_MDS. OBD_CONNECT_MNE_SWAB was used for 2.2 clients for MNE swabbing. OBD_CONNECT_MDS_MDS flag is used to skip export fail during reconnect for MDS-MDS interaction. Locks for MDS-MDS are not added to a waiting_locks_list because there is no eviction and so on. This leads to a situation when MGS can not cancel locks for a clients if client doesn't receive/respond to a blocking ast.