RHEL6: Linux NFS4 server seeing a lot of these messages in a short time "WARNING: at net/sunrpc/sched.c:673 rpc_exit_task"

Issue

• Our NFS server is seeing a lot of WARNING: at net/sunrpc/sched.c:673 rpc_exit_task messages in a short period off time.

Jul 19 03:38:56 localhost kernel: ------------[ cut here ]------------
Jul 19 03:38:56 localhost kernel: WARNING: at net/sunrpc/sched.c:673 rpc_exit_task+0x5c/0x60 [sunrpc]() (Tainted: G        W  ---------------   )
Jul 19 03:38:56 localhost kernel: Hardware name: VMware Virtual Platform
Jul 19 03:38:56 localhost kernel: Modules linked in: nfnetlink_queue nfnetlink_log nfnetlink bluetooth rfkill bridge nfs fscache nfsd lockd nfs_acl auth_rpcgss sunrpc exportfs autofs4 8021q garp stp llc ipv6 ppdev parport_pc parport microcode vmware_balloon sg i2c_piix4 i2c_core shpchp ext4 jbd2 mbcache sd_mod crc_t10dif sr_mod cdrom vmxnet3 vmw_pvscsi pata_acpi ata_generic ata_piix dm_mirror dm_region_hash dm_log dm_mod [last unloaded: speedstep_lib]
Jul 19 03:38:56 localhost kernel: Pid: 2200, comm: rpciod/4 Tainted: G        W  ---------------    2.6.32-504.8.1.el6.x86_64 #1
Jul 19 03:38:56 localhost kernel: Call Trace:
Jul 19 03:38:56 localhost kernel: [<ffffffff81074df7>] ? warn_slowpath_common+0x87/0xc0
Jul 19 03:38:56 localhost kernel: [<ffffffffa0255e60>] ? rpc_exit_task+0x0/0x60 [sunrpc]
Jul 19 03:38:56 localhost kernel: [<ffffffff81074e4a>] ? warn_slowpath_null+0x1a/0x20
Jul 19 03:38:56 localhost kernel: [<ffffffffa0255ebc>] ? rpc_exit_task+0x5c/0x60 [sunrpc]
Jul 19 03:38:56 localhost kernel: [<ffffffffa02568e7>] ? __rpc_execute+0x77/0x350 [sunrpc]
Jul 19 03:38:56 localhost kernel: [<ffffffffa0256c60>] ? rpc_async_schedule+0x0/0x40 [sunrpc]
Jul 19 03:38:56 localhost kernel: [<ffffffffa0256c8a>] ? rpc_async_schedule+0x2a/0x40 [sunrpc]
Jul 19 03:38:56 localhost kernel: [<ffffffff81097fe0>] ? worker_thread+0x170/0x2a0
Jul 19 03:38:56 localhost kernel: [<ffffffff8109eb00>] ? autoremove_wake_function+0x0/0x40
Jul 19 03:38:56 localhost kernel: [<ffffffff81097e70>] ? worker_thread+0x0/0x2a0
Jul 19 03:38:56 localhost kernel: [<ffffffff8109e66e>] ? kthread+0x9e/0xc0
Jul 19 03:38:56 localhost kernel: [<ffffffff8100c20a>] ? child_rip+0xa/0x20
Jul 19 03:38:56 localhost kernel: [<ffffffff8109e5d0>] ? kthread+0x0/0xc0
Jul 19 03:38:56 localhost kernel: [<ffffffff8100c200>] ? child_rip+0x0/0x20
Jul 19 03:38:56 localhost kernel: ---[ end trace db162467539e59b4 ]---
Jul 19 03:38:57 localhost abrtd: Directory 'oops-2015-07-19-03:38:57-2402-1' creation detected
Jul 19 03:38:57 localhost abrt-dump-oops: Reported 1 kernel oopses to Abrt

$ grep -h "sched.c:673 rpc_exit_task" /var/log/messages* | tail 
Jul 19 03:25:27 localhost kernel: WARNING: at net/sunrpc/sched.c:673 rpc_exit_task+0x5c/0x60 [sunrpc]() (Tainted: G        W  ---------------   )
Jul 19 03:25:51 localhost kernel: WARNING: at net/sunrpc/sched.c:673 rpc_exit_task+0x5c/0x60 [sunrpc]() (Tainted: G        W  ---------------   )
Jul 19 03:30:04 localhost kernel: WARNING: at net/sunrpc/sched.c:673 rpc_exit_task+0x5c/0x60 [sunrpc]() (Tainted: G        W  ---------------   )
Jul 19 03:31:23 localhost kernel: WARNING: at net/sunrpc/sched.c:673 rpc_exit_task+0x5c/0x60 [sunrpc]() (Tainted: G        W  ---------------   )
Jul 19 03:32:53 localhost kernel: WARNING: at net/sunrpc/sched.c:673 rpc_exit_task+0x5c/0x60 [sunrpc]() (Tainted: G        W  ---------------   )
Jul 19 03:34:06 localhost kernel: WARNING: at net/sunrpc/sched.c:673 rpc_exit_task+0x5c/0x60 [sunrpc]() (Tainted: G        W  ---------------   )
Jul 19 03:35:05 localhost kernel: WARNING: at net/sunrpc/sched.c:673 rpc_exit_task+0x5c/0x60 [sunrpc]() (Tainted: G        W  ---------------   )
Jul 19 03:35:37 localhost kernel: WARNING: at net/sunrpc/sched.c:673 rpc_exit_task+0x5c/0x60 [sunrpc]() (Tainted: G        W  ---------------   )
Jul 19 03:36:45 localhost kernel: WARNING: at net/sunrpc/sched.c:673 rpc_exit_task+0x5c/0x60 [sunrpc]() (Tainted: G        W  ---------------   )
Jul 19 03:38:56 localhost kernel: WARNING: at net/sunrpc/sched.c:673 rpc_exit_task+0x5c/0x60 [sunrpc]() (Tainted: G        W  ---------------   )