INFO: task modprobe:17780 blocked for more than 120 seconds. after restoring the /etc/ folder

A few questions but the main one is:

How to debug this modprobe hung task?

Background:

This started to happen when /etc/ was accidentally removed. We recovered the folder by copying over from another host and modifying a bunch of files including the networking, hosts, resolv.conf any any other that had references to the previous host.

Also modified the UUID in /etc/fstab for /boot.

However we may have missed something still.

One of the other issues is also that udevadm trigger causes the 70-persistent-net rules to be regenerated, which doesn't happen on other hosts. ( Have not rebooted yet since recovering. Hoping to trace the remainder of the issues before rebooting to ensure highest chance of recovery. It's an important server. ) These issues are on a CentOS 6.7 distribution.

Hoping for any tips.

Cheers,

Apr  6 23:59:39 devlan-p01 kernel: INFO: task modprobe:17780 blocked for more than 120 seconds.
Apr  6 23:59:39 devlan-p01 kernel:      Not tainted 2.6.32-504.16.2.el6.x86_64 #1
Apr  6 23:59:39 devlan-p01 kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Apr  6 23:59:39 devlan-p01 kernel: modprobe      D 0000000000000020     0 17780  17668 0x00000080
Apr  6 23:59:39 devlan-p01 kernel: ffff88142329be18 0000000000000086 0000000000000000 ffff88142329be40
Apr  6 23:59:39 devlan-p01 kernel: ffff88161be0d520 7fffffffffffffff 000367dbc5652eba ffffffff8152a9cd
Apr  6 23:59:39 devlan-p01 kernel: ffffffff8100bb8e 0000000139289b3d ffff88161be0dad8 ffff88142329bfd8
Apr  6 23:59:39 devlan-p01 kernel: Call Trace:
Apr  6 23:59:39 devlan-p01 kernel: [<ffffffff8152a9cd>] ? wait_for_common+0x14d/0x180
Apr  6 23:59:39 devlan-p01 kernel: [<ffffffff8100bb8e>] ? apic_timer_interrupt+0xe/0x20
Apr  6 23:59:39 devlan-p01 kernel: [<ffffffff810585cf>] ? mutex_spin_on_owner+0x9f/0xc0
Apr  6 23:59:39 devlan-p01 kernel: [<ffffffff8152b7a6>] __mutex_lock_slowpath+0x96/0x210
Apr  6 23:59:39 devlan-p01 kernel: [<ffffffff8152b2cb>] mutex_lock+0x2b/0x50
Apr  6 23:59:39 devlan-p01 kernel: [<ffffffff81457b8d>] unregister_pernet_subsys+0x1d/0x40
Apr  6 23:59:39 devlan-p01 kernel: [<ffffffffa017c252>] iptable_mangle_fini+0x26/0x28 [iptable_mangle]
Apr  6 23:59:39 devlan-p01 kernel: [<ffffffff810bd004>] sys_delete_module+0x194/0x260
Apr  6 23:59:39 devlan-p01 kernel: [<ffffffff8100b072>] system_call_fastpath+0x16/0x1b