Issue

NFS calls gets hung while trying to decode server reply containing a key for ownership/group ownership attributes of file/s :

 #0 [ffff88200db07038] schedule at ffffffff815489d0
 #1 [ffff88200db07110] schedule_timeout at ffffffff81549945
 #2 [ffff88200db071c0] wait_for_common at ffffffff815495a3
 #3 [ffff88200db07250] wait_for_completion at ffffffff815496dd
 #4 [ffff88200db07260] call_usermodehelper_exec at ffffffff8109e9dc
 #5 [ffff88200db072b0] call_sbin_request_key at ffffffff812384f9
 #6 [ffff88200db07420] request_key_and_link at ffffffff81238024
 #7 [ffff88200db074c0] request_key at ffffffff812381f0
 #8 [ffff88200db07510] nfs_idmap_request_key at ffffffffa0469fe5 [nfs]
 #9 [ffff88200db07570] nfs_idmap_lookup_id at ffffffffa046a624 [nfs]
#10 [ffff88200db075c0] nfs_map_name_to_uid at ffffffffa046aa65 [nfs]
#11 [ffff88200db075f0] decode_getfattr_attrs at ffffffffa0464a07 [nfs]
#12 [ffff88200db07690] decode_getfattr_generic.clone.0 at ffffffffa0464acb [nfs]
#13 [ffff88200db076f0] decode_getfattr at ffffffffa0464c03 [nfs]
#14 [ffff88200db07700] nfs4_xdr_dec_access at ffffffffa04652b0 [nfs]
#15 [ffff88200db077a0] rpcauth_unwrap_resp at ffffffffa0398304 [sunrpc]
#16 [ffff88200db077f0] call_decode at ffffffffa038c9a9 [sunrpc]
#17 [ffff88200db07850] __rpc_execute at ffffffffa0396967 [sunrpc]
#18 [ffff88200db078c0] rpc_execute at ffffffffa0396ca1 [sunrpc]
#19 [ffff88200db078f0] rpc_run_task at ffffffffa038d455 [sunrpc]
#20 [ffff88200db07910] rpc_call_sync at ffffffffa038d572 [sunrpc]
#21 [ffff88200db07970] _nfs4_call_sync at ffffffffa0458d8e [nfs]
#22 [ffff88200db07980] _nfs4_proc_access at ffffffffa0457b2c [nfs]
#23 [ffff88200db07a60] nfs4_proc_access at ffffffffa0457bfb [nfs]
#24 [ffff88200db07ab0] nfs_do_access at ffffffffa04347bc [nfs]
#25 [ffff88200db07b40] nfs_permission at ffffffffa0434908 [nfs]
#26 [ffff88200db07b70] __link_path_walk at ffffffff811a9f93
#27 [ffff88200db07c50] __link_path_walk at ffffffff811aa3b3
#28 [ffff88200db07d30] path_walk at ffffffff811ab1fa
#29 [ffff88200db07d70] filename_lookup at ffffffff811ab40b
#30 [ffff88200db07db0] user_path_at at ffffffff811ac537
#31 [ffff88200db07e80] vfs_fstatat at ffffffff8119f8e0
#32 [ffff88200db07ee0] vfs_stat at ffffffff8119fa5b
#33 [ffff88200db07ef0] sys_newstat at ffffffff8119fa84
#34 [ffff88200db07f80] system_call_fastpath at ffffffff8100b0d2

Task hung messages will also appear :

INFO: task sapstartsrv:3869 blocked for more than 120 seconds.