RHEL6.8 or RHEL7: NFS client process hangs hung_tasks blocked in "__fscache_wait_on_page_write"

Issue

• On an NFS client, one or more processes hang with the following messages showing blocked in __fscache_wait_on_page_write

kernel: INFO: task firefox:21313 blocked for more than 120 seconds.
kernel:      Tainted: G           -- ------------  T 2.6.32-642.el6.x86_64 #1
kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
kernel: firefox       D 000000000000000d     0 21313      1 0x00000084
kernel: ffff884050bf3b68 0000000000000086 00ffffffa0429790 0000000000000000
kernel: ffff884050bf3ae8 ffff880124e16ec0 ffff884050bf3ae8 ffffffff81189130
kernel: 0000000000016ec0 0000000000000000 ffff8840513ed068 ffff884050bf3fd8
kernel: Call Trace:
kernel: [<ffffffff81189130>] ? mem_cgroup_get_reclaim_stat_from_page+0x20/0x70
kernel: [<ffffffff810a6dee>] ? prepare_to_wait+0x4e/0x80
kernel: [<ffffffffa042d475>] __fscache_wait_on_page_write+0x75/0xb0 [fscache]
kernel: [<ffffffff810a6ac0>] ? autoremove_wake_function+0x0/0x40
kernel: [<ffffffffa042c608>] ? __fscache_uncache_page+0x58/0x140 [fscache]
kernel: [<ffffffffa042d57c>] __fscache_uncache_all_inode_pages+0xcc/0x150 [fscache]
kernel: [<ffffffffa051e27e>] nfs_fscache_open_file+0x5e/0x100 [nfs]
kernel: [<ffffffffa04e4e28>] nfs_open+0x78/0x90 [nfs]
kernel: [<ffffffffa04e3080>] ? nfs_file_open+0x0/0xc0 [nfs]
kernel: [<ffffffffa04e30ed>] nfs_file_open+0x6d/0xc0 [nfs]
kernel: [<ffffffff81196e32>] __dentry_open+0x122/0x380
kernel: [<ffffffff8123bdaf>] ? security_inode_permission+0x1f/0x30
kernel: [<ffffffff811971a4>] nameidata_to_filp+0x54/0x70
kernel: [<ffffffff811ad090>] do_filp_open+0x6d0/0xd20
kernel: [<ffffffff810eb0ca>] ? audit_alloc_name+0x6a/0xb0
kernel: [<ffffffff810eb964>] ? __audit_getname+0xc4/0xe0
kernel: [<ffffffff811ba252>] ? alloc_fd+0x92/0x160
kernel: [<ffffffff81196bd7>] do_sys_open+0x67/0x130
kernel: [<ffffffff81196ce0>] sys_open+0x20/0x30
kernel: [<ffffffff8100b0d2>] system_call_fastpath+0x16/0x1b