Major - P3 Looks like if fsync flush is ran just when the system is shutting down, the engine gets ripped out from underneath the command and it AVs:
m30000| 2014-11-21T20:00:06.109+0000 I CONTROL [signalProcessingThread] got signal 15 (Terminated), will terminate after current cmd ends m30000| 2014-11-21T20:00:06.109+0000 I COMMAND [signalProcessingThread] now exiting m30000| 2014-11-21T20:00:06.109+0000 I NETWORK [signalProcessingThread] shutdown: going to close listening sockets... m30000| 2014-11-21T20:00:06.109+0000 I NETWORK [signalProcessingThread] closing listening socket: 17 m30000| 2014-11-21T20:00:06.109+0000 I NETWORK [signalProcessingThread] closing listening socket: 18 m30000| 2014-11-21T20:00:06.109+0000 I NETWORK [signalProcessingThread] removing socket file: /tmp/mongodb-30000.sock m30000| 2014-11-21T20:00:06.109+0000 I NETWORK [signalProcessingThread] shutdown: going to flush diaglog... m30000| 2014-11-21T20:00:06.109+0000 I NETWORK [signalProcessingThread] shutdown: going to close sockets... m30000| 2014-11-21T20:00:06.109+0000 I STORAGE [signalProcessingThread] WiredTigerKVEngine shutting down ... m30000| 2014-11-21T20:00:06.265+0000 F - [conn44] Invalid access at address: 0x7cc m30000| 2014-11-21T20:00:06.274+0000 F - [conn44] Got signal: 11 (Segmentation fault). ... m30000| mongod(mongo::printStackTrace(std::ostream&) 0x29) [0xf3ebd9] m30000| mongod( 0xB3E542) [0xf3e542] m30000| mongod( 0xB3E86E) [0xf3e86e] m30000| libpthread.so.0( 0xECA0) [0x2b30c24a5ca0] m30000| mongod(__wt_realloc 0xE0) [0x1343e50] m30000| mongod(__wt_meta_track_on 0x83) [0x1342703] m30000| mongod(__wt_txn_checkpoint 0x815) [0x136b9d5] m30000| mongod( 0xF60116) [0x1360116] m30000| mongod(mongo::WiredTigerKVEngine::flushAllFiles(bool) 0xAE) [0xd531de] m30000| mongod(mongo::FSyncCommand::run(mongo::OperationContext*, std::string const&, mongo::BSONObj&, int, std::string&, mongo::BSONObjBuilder&, bool) 0x2D5) [0x946605] m30000| mongod(mongo::_execCommand(mongo::OperationContext*, mongo::Command*, std::string const&, mongo::BSONObj&, int, std::string&, mongo::BSONObjBuilder&, bool) 0x34) [0x9b60b4] m30000| mongod(mongo::Command::execCommand(mongo::OperationContext*, mongo::Command*, int, char const*, mongo::BSONObj&, mongo::BSONObjBuilder&, bool) 0xC62) [0x9b6f52] m30000| mongod(mongo::_runCommands(mongo::OperationContext*, char const*, mongo::BSONObj&, mongo::_BufBuilder<mongo::TrivialAllocator>&, mongo::BSONObjBuilder&, bool, int) 0x2D0) [0x9b7ac0] m30000| mongod(mongo::newRunQuery(mongo::OperationContext*, mongo::Message&, mongo::QueryMessage&, mongo::CurOp&, mongo::Message&, bool) 0x101C) [0xbb8f7c] m30000| mongod(mongo::assembleResponse(mongo::OperationContext*, mongo::Message&, mongo::DbResponse&, mongo::HostAndPort const&, bool) 0xBB3) [0xa9d3d3] m30000| mongod(mongo::MyMessageHandler::process(mongo::Message&, mongo::AbstractMessagingPort*, mongo::LastError*) 0xE0) [0x7df9f0] m30000| mongod(mongo::PortMessageServer::handleIncomingMsg(void*) 0x421) [0xefb211] m30000| libpthread.so.0( 0x683D) [0x2b30c249d83d] m30000| libc.so.6(clone 0x6D) [0x2b30c3327fcd]