rgmanager blocks or is unable to manage services when using Redundant Ring Protocol (RRP) in a RHEL 6 Update 3 or earlier High Availability cluster

Issue

• When I start rgmanager it just hangs:

May 15 03:54:51 node1 kernel: INFO: task rgmanager:2420 blocked for more than 120 seconds.
May 15 03:54:51 node1 kernel:      Not tainted 2.6.32-431.3.1.el6.x86_64 #1
May 15 03:54:51 node1 kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
May 15 03:54:51 node1 kernel: rgmanager     D 0000000000000002     0  2420   2418 0x00000000
May 15 03:54:51 node1 kernel: ffff880336a93c98 0000000000000082 0000000000000000 ffff880336a93c5c
May 15 03:54:51 node1 kernel: ffff880300000000 ffff88033fc23480 ffff880028296840 0000000000000200
May 15 03:54:51 node1 kernel: ffff8803356425f8 ffff880336a93fd8 000000000000fbc8 ffff8803356425f8
May 15 03:54:51 node1 kernel: Call Trace:
May 15 03:54:51 node1 kernel: [<ffffffff815287c5>] schedule_timeout+0x215/0x2e0
May 15 03:54:51 node1 kernel: [<ffffffff81527920>] ? thread_return+0x4e/0x76e
May 15 03:54:51 node1 kernel: [<ffffffff81285392>] ? kobject_uevent_env+0x202/0x620
May 15 03:54:51 node1 kernel: [<ffffffff81528443>] wait_for_common+0x123/0x180
May 15 03:54:51 node1 kernel: [<ffffffff81065df0>] ? default_wake_function+0x0/0x20
May 15 03:54:51 node1 kernel: [<ffffffff8152855d>] wait_for_completion+0x1d/0x20
May 15 03:54:51 node1 kernel: [<ffffffffa022ef79>] dlm_new_lockspace+0x999/0xa30 [dlm]
May 15 03:54:51 node1 kernel: [<ffffffffa0236ff1>] device_write+0x311/0x720 [dlm]
May 15 03:54:51 node1 kernel: [<ffffffff81065df0>] ? default_wake_function+0x0/0x20
May 15 03:54:51 node1 kernel: [<ffffffff812263d6>] ? security_file_permission+0x16/0x20
May 15 03:54:51 node1 kernel: [<ffffffff81188f88>] vfs_write+0xb8/0x1a0
May 15 03:54:51 node1 kernel: [<ffffffff81189881>] sys_write+0x51/0x90
May 15 03:54:51 node1 kernel: [<ffffffff8100b072>] system_call_fastpath+0x16/0x1b

• I can't manage any services with clusvcadm or Conga