Tasks blocked on CIFS client filesystem

Issue

• Intermittent server hangs on multiple servers

INFO: task mktnet:5855 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
mktnet        D 0000000000000003     0  5855   5841 0x00000080
 ffff880632007ba8 0000000000000086 0000000000000000 ffff88000004ca00
 ffffea000f012080 ffffea0000000000 ffff880632007b38 ffffffff81119ec7
 ffff8806337de638 ffff880632007fd8 000000000000fb88 ffff8806337de638
Call Trace:
 [<ffffffff81119ec7>] ? unlock_page+0x27/0x30
 [<ffffffff8150f1ee>] __mutex_lock_slowpath+0x13e/0x180
 [<ffffffff8150f08b>] mutex_lock+0x2b/0x50
 [<ffffffff8119045b>] do_lookup+0x11b/0x230
 [<ffffffff81190ca4>] __link_path_walk+0x734/0x1030
 [<ffffffff8119182a>] path_walk+0x6a/0xe0
 [<ffffffff811919fb>] do_path_lookup+0x5b/0xa0
 [<ffffffff81192687>] user_path_at+0x57/0xa0
 [<ffffffff81186874>] ? cp_new_stat+0xe4/0x100
 [<ffffffff81186a9c>] vfs_fstatat+0x3c/0x80
 [<ffffffff81186b4e>] vfs_lstat+0x1e/0x20
 [<ffffffff81186b74>] sys_newlstat+0x24/0x50
 [<ffffffff810dc645>] ? __audit_syscall_exit+0x265/0x290
 [<ffffffff8100b072>] system_call_fastpath+0x16/0x1b
Kernel panic - not syncing: hung_task: blocked tasks