After upgrading to 1.8.2 and enabling chunk balancer again while we had one slave offline, it started first just fine and then segfaulted after we restarted the slave with:

Mon Jun 27 10:32:54 Invalid access at address: 0

Mon Jun 27 10:32:54 Got signal: 11 (Segmentation fault).
Mon Jun 27 10:32:54 Backtrace:
0x8a8039 0x8a8610 0x7f5fc8d398f0 0x7f5fc8abe787 0x7f5fc8abf04c 0x6d7863 0x6d10f2 0x7dd347 0x7de8f1 0x647e45 0x64b3de 0x7547a5 0x759ec8 0x8a8fce 0x8bb630 0x7
f5fc8d309ca 0x7f5fc82df70d
/usr/bin/mongod(_ZN5mongo10abruptQuitEi+0x399) [0x8a8039]
/usr/bin/mongod(_ZN5mongo24abruptQuitWithAddrSignalEiP7siginfoPv+0x220) [0x8a8610]
/lib/libpthread.so.0(+0xf8f0) [0x7f5fc8d398f0]
/usr/lib/libstdc++.so.6(_ZNSs4_Rep8_M_cloneERKSaIcEm+0x47) [0x7f5fc8abe787]
/usr/lib/libstdc++.so.6(_ZNSsC1ERKSs+0x3c) [0x7f5fc8abf04c]
/usr/bin/mongod(_ZNK5mongo11ReplSetImpl16_summarizeStatusERNS_14BSONObjBuilderE+0x753) [0x6d7863]
/usr/bin/mongod(_ZN5mongo19CmdReplSetGetStatus3runERKSsRNS_7BSONObjERSsRNS_14BSONObjBuilderEb+0x122) [0x6d10f2]
/usr/bin/mongod(_ZN5mongo11execCommandEPNS_7CommandERNS_6ClientEiPKcRNS_7BSONObjERNS_14BSONObjBuilderEb+0x227) [0x7dd347]
/usr/bin/mongod(_ZN5mongo12_runCommandsEPKcRNS_7BSONObjERNS_10BufBuilderERNS_14BSONObjBuilderEbi+0x831) [0x7de8f1]
/usr/bin/mongod(_ZN5mongo11runCommandsEPKcRNS_7BSONObjERNS_5CurOpERNS_10BufBuilderERNS_14BSONObjBuilderEbi+0x35) [0x647e45]
/usr/bin/mongod(ZN5mongo8runQueryERNS_7MessageERNS_12QueryMessageERNS_5CurOpES1+0x324e) [0x64b3de]
/usr/bin/mongod() [0x7547a5]
/usr/bin/mongod(_ZN5mongo16assembleResponseERNS_7MessageERNS_10DbResponseERKNS_8SockAddrE+0x5b8) [0x759ec8]
/usr/bin/mongod(_ZN5mongo10connThreadEPNS_13MessagingPortE+0x21e) [0x8a8fce]
/usr/bin/mongod(thread_proxy+0x80) [0x8bb630]
/lib/libpthread.so.0(+0x69ca) [0x7f5fc8d309ca]
/lib/libc.so.6(clone+0x6d) [0x7f5fc82df70d]
Mon Jun 27 10:32:54 Invalid access at address: 0x4

Mon Jun 27 10:32:54 Got signal: 11 (Segmentation fault).
Mon Jun 27 10:32:54 Backtrace:
0x8a8039 0x8a8610 0x7f5fc8d398f0 0x7128f5 0x711052 0x74cdb1 0x876ed7 0x7dd347 0x7de8f1 0x647e45 0x64b3de 0x7547a5 0x759ec8 0x8a8fce 0x8bb630 0x7f5fc8d309ca
0x7f5fc82df70d
/usr/bin/mongod(_ZN5mongo10abruptQuitEi+0x399) [0x8a8039]
/usr/bin/mongod(_ZN5mongo24abruptQuitWithAddrSignalEiP7siginfoPv+0x220) [0x8a8610]
/lib/libpthread.so.0(+0xf8f0) [0x7f5fc8d398f0]
/usr/bin/mongod() [0x7128f5]
/usr/bin/mongod(_ZN5mongo5logOpEPKcS1_RKNS_7BSONObjEPS2_Pb+0x42) [0x711052]
/usr/bin/mongod(_ZN5mongo7Helpers11removeRangeERKSsRKNS_7BSONObjES5_bbPNS0_14RemoveCallbackE+0x791) [0x74cdb1]
/usr/bin/mongod(_ZN5mongo16MoveChunkCommand3runERKSsRNS_7BSONObjERSsRNS_14BSONObjBuilderEb+0x8047) [0x876ed7]
/usr/bin/mongod(_ZN5mongo11execCommandEPNS_7CommandERNS_6ClientEiPKcRNS_7BSONObjERNS_14BSONObjBuilderEb+0x227) [0x7dd347]
/usr/bin/mongod(_ZN5mongo12_runCommandsEPKcRNS_7BSONObjERNS_10BufBuilderERNS_14BSONObjBuilderEbi+0x831) [0x7de8f1]
/usr/bin/mongod(_ZN5mongo11runCommandsEPKcRNS_7BSONObjERNS_5CurOpERNS_10BufBuilderERNS_14BSONObjBuilderEbi+0x35) [0x647e45]
/usr/bin/mongod(ZN5mongo8runQueryERNS_7MessageERNS_12QueryMessageERNS_5CurOpES1+0x324e) [0x64b3de]
/usr/bin/mongod() [0x7547a5]
/usr/bin/mongod(_ZN5mongo16assembleResponseERNS_7MessageERNS_10DbResponseERKNS_8SockAddrE+0x5b8) [0x759ec8]
/usr/bin/mongod(_ZN5mongo10connThreadEPNS_13MessagingPortE+0x21e) [0x8a8fce]
/usr/bin/mongod(thread_proxy+0x80) [0x8bb630]
/lib/libpthread.so.0(+0x69ca) [0x7f5fc8d309ca] /lib/libc.so.6(clone+0x6d) [0x7f5fc82df70d]