from dmesg:
[  342.010087] binder: 611:611 refcount change on invalid ref 0
[  342.010101] binder: 611:611 refcount change on invalid ref 0
[  342.010115] binder: 611:611 transaction failed 29189, size 96-0
[  363.034718] init: powerd main process (611) killed by SEGV signal
[  363.035238] init: powerd main process ended, respawning
[  363.212752] binder: 633:633 refcount change on invalid ref 0
[  363.212765] binder: 633:633 refcount change on invalid ref 0
[  363.212779] binder: 633:633 transaction failed 29189, size 96-0

from /var/log/syslog

Aug 11 17:33:33 ubuntu-phablet kernel: [  405.460910] init: powerd main process (644) killed by SEGV signal
Aug 11 17:33:33 ubuntu-phablet kernel: [  405.461058] init: powerd main process ended, respawning
Aug 11 17:33:33 ubuntu-phablet powerd[654]: No backlight devices found
Aug 11 17:33:33 ubuntu-phablet powerd[654]: Could not read maximum brightness, guessing at dim/bright values
Aug 11 17:33:33 ubuntu-phablet kernel: [  405.647252] binder: 654:654 refcount change on invalid ref 0
Aug 11 17:33:33 ubuntu-phablet kernel: [  405.647266] binder: 654:654 refcount change on invalid ref 0
Aug 11 17:33:33 ubuntu-phablet kernel: [  405.647280] binder: 654:654 transaction failed 29189, size 96-0