echo c > /proc/sysrq-trigger
---> drivers/tty/sysrq.c
sysrq_init
sysrq_init_procfs
write_sysrq_trigger
__handle_sysrq
__handle_sysrq
__sysrq_get_key_op
op_p->handler
sysrq_crash_op
sysrq_handle_crash
panic("sysrq triggered crash\n");