Last night we had two OSSs panic at virtually the same time with and LBUG error being thrown. We just updated our servers and clients to 2.1.2-4chaos from 2.1.2-3chaos releases with the past 2 days and had not experienced this issue with the previous release. Below is a sample of the console log from one of the servers. I have also captured all the console messages up until the system panicked and am attaching it.

LustreError: 9044:0:(ost_handler.c:1673:ost_prolong_lock_one()) ASSERTION(lock->l_export == opd->opd_exp) failed
LustreError: 9120:0:(ost_handler.c:1673:ost_prolong_lock_one()) ASSERTION(lock->l_export == opd->opd_exp) failed
LustreError: 9120:0:(ost_handler.c:1673:ost_prolong_lock_one()) LBUG
Pid: 9120, comm: ll_ost_io_341

Call Trace:
LustreError: 9083:0:(ost_handler.c:1673:ost_prolong_lock_one()) ASSERTION(lock->l_export == opd->opd_exp) failed
LustreError: 9083:0:(ost_handler.c:1673:ost_prolong_lock_one()) LBUG
[<ffffffffa0440895>] libcfs_debug_dumpstack+0x55/0x80 [libcfs]
Pid: 9083, comm: ll_ost_io_304