(gdb) backtrace
#0  0x00002b5be602b294 in _int_free () from /lib64/libc.so.6
#1  0x0000000000684541 in grid::DepositParticlePositions (this=0x2b5be6370760 <main_arena>, TargetGrid=0x0, DepositTime=<unavailable>, DepositField=0) at Grid_DepositParticlePositions.C:495
#2  0x00000000004c3a8d in DepositParticleMassFieldChildren (DepositGrid=0x2b5be6370760 <main_arena>, Grid=0x0, DepositTime=<unavailable>) at DepositParticleMassField.C:94
#3  0x00000000004c377c in DepositParticleMassField (Grid=0x2b5be6370760 <main_arena>, TimeMidStep=<unavailable>) at DepositParticleMassField.C:76
#4  0x00000000007e6c05 in PrepareDensityField (LevelArray=0x2b5be6370760 <main_arena>, level=0, MetaData=0x0, When=<unavailable>, SiblingGridListStorage=0x31a7f5b0) at PrepareDensityField.C:166
#5  0x00000000004f9250 in EvolveLevel (MetaData=0x2b5be6370760 <main_arena>, LevelArray=0x0, level=0, dtLevelAbove=<unavailable>, Exterior=0x31a7f5b0, ImplicitSolver=0x1, dt0=<unavailable>,
    SiblingGridListStorage=0x1) at EvolveLevel.C:519
#6  0x00000000004f9c2b in EvolveLevel (MetaData=0x2b5be6370760 <main_arena>, LevelArray=0x0, level=0, dtLevelAbove=<unavailable>, Exterior=0x31a7f5b0, ImplicitSolver=0x1, dt0=<unavailable>,
    SiblingGridListStorage=0x1) at EvolveLevel.C:874
#7  0x00000000004f9c2b in EvolveLevel (MetaData=0x2b5be6370760 <main_arena>, LevelArray=0x0, level=0, dtLevelAbove=<unavailable>, Exterior=0x31a7f5b0, ImplicitSolver=0x1, dt0=<unavailable>,
    SiblingGridListStorage=0x1) at EvolveLevel.C:874
#8  0x00000000004ea21c in EvolveHierarchy (TopGrid=..., MetaData=..., Exterior=0x0, ImplicitSolver=0x31a7f5b0, LevelArray=0x1, Initialdt=<unavailable>) at EvolveHierarchy.C:565
#9  0x000000000040c37b in main (argc=3, argv=0x7fff00d768f8) at enzo.C:822