sshd sessions seem to get blocked

Issue

• sshd processes are getting blocked. In /var/log/messages we see the following:

[root@localhost log]# grep blocked /var/log/messages
Jun  8 17:33:47 localhost kernel: INFO: task sshd:64120 blocked for more than 120 seconds.
Jun  8 17:35:47 localhost kernel: INFO: task sshd:64120 blocked for more than 120 seconds.
Jun  8 17:35:47 localhost kernel: INFO: task sshd:3994 blocked for more than 120 seconds.
Jun  8 17:37:47 localhost kernel: INFO: task sshd:64120 blocked for more than 120 seconds.
Jun  8 17:37:47 localhost kernel: INFO: task sshd:3994 blocked for more than 120 seconds.
Jun  8 17:39:47 localhost kernel: INFO: task sshd:64120 blocked for more than 120 seconds.
Jun  8 17:39:47 localhost kernel: INFO: task sshd:3994 blocked for more than 120 seconds.
Jun  8 17:41:47 localhost kernel: INFO: task sshd:64120 blocked for more than 120 seconds.
Jun  8 17:41:47 localhost kernel: INFO: task sshd:3994 blocked for more than 120 seconds.
Jun  8 17:43:47 localhost kernel: INFO: task sshd:64120 blocked for more than 120 seconds.

Jun  8 17:33:47 localhost kernel: INFO: task sshd:64120 blocked for more than 120 seconds.
Jun  8 17:33:47 localhost kernel:      Not tainted 2.6.32-504.16.2.el6.x86_64 #1
Jun  8 17:33:47 localhost kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Jun  8 17:33:47 localhost kernel: sshd          D 0000000000000000     0 64120   2534 0x00000000
Jun  8 17:33:47 localhost kernel: ffff8812047bdb28 0000000000000082 0000000000000000 0000000100000001
Jun  8 17:33:47 localhost kernel: 0000000000000400 ffff881202c381a8 000001c41465351b 0000000000000001
Jun  8 17:33:47 localhost kernel: 0000000000000001 00000001001909ad ffff881221aa45f8 ffff8812047bdfd8
Jun  8 17:33:47 localhost kernel: Call Trace:
Jun  8 17:33:47 localhost kernel: [<ffffffff8152ad25>] schedule_timeout+0x215/0x2e0
Jun  8 17:33:47 localhost kernel: [<ffffffff8105bd53>] ? __wake_up+0x53/0x70
Jun  8 17:33:47 localhost kernel: [<ffffffff8152a9a3>] wait_for_common+0x123/0x180
Jun  8 17:33:47 localhost kernel: [<ffffffff81064bc0>] ? default_wake_function+0x0/0x20
Jun  8 17:33:47 localhost kernel: [<ffffffff8152aabd>] wait_for_completion+0x1d/0x20
Jun  8 17:33:47 localhost kernel: [<ffffffff81098461>] flush_cpu_workqueue+0x61/0x90
Jun  8 17:33:47 localhost kernel: [<ffffffff81098510>] ? wq_barrier_func+0x0/0x20
Jun  8 17:33:47 localhost kernel: [<ffffffff81098f34>] flush_workqueue+0x54/0x80
Jun  8 17:33:47 localhost kernel: [<ffffffff81098f75>] flush_scheduled_work+0x15/0x20
Jun  8 17:33:47 localhost kernel: [<ffffffff813388bc>] tty_ldisc_release+0x3c/0x90
Jun  8 17:33:47 localhost kernel: [<ffffffff81332bdb>] tty_release_dev+0x40b/0x5e0
Jun  8 17:33:47 localhost kernel: [<ffffffff8133385c>] ? n_tty_set_room+0x4c/0x80
Jun  8 17:33:47 localhost kernel: [<ffffffff81332dce>] tty_release+0x1e/0x30
Jun  8 17:33:47 localhost kernel: [<ffffffff8118fb85>] __fput+0xf5/0x210
Jun  8 17:33:47 localhost kernel: [<ffffffff8118fcc5>] fput+0x25/0x30
Jun  8 17:33:47 localhost kernel: [<ffffffff8118af1d>] filp_close+0x5d/0x90
Jun  8 17:33:47 localhost kernel: [<ffffffff8118aff5>] sys_close+0xa5/0x100
Jun  8 17:33:47 localhost kernel: [<ffffffffa0262938>] efab_linux_trampoline_handler_close+0x78/0x460 [onload]
Jun  8 17:33:47 localhost kernel: [<ffffffff8118ec41>] ? sys_read+0x51/0x90
Jun  8 17:33:47 localhost kernel: [<ffffffff8100b072>] system_call_fastpath+0x16/0x1b