%r3,%r10 3.465597 Call Trace: 3.465599 (<0400000000000000> 0x400000000000000) 3.465602 <000000000048c77e> raw3215_wakeup+0x2e/0x40 3.465607 <0000000000134d66> tasklet_action+0x96/0x168 3.465612 <000000000013423c> __do_softirq+0xd8/0x21c 3.465615 <0000000000134678> irq_exit+0xa8/0xac 3.465617 <000000000046c232> do_IRQ+0x182/0x248 3.465621 <00000000005c8296> io_return+0x0/0x8 3.465625 <00000000005c7cac> vtime_stop_cpu+0x4c/0xb8 3.465629 (<0000000000194e06> tick_nohz_idle_enter+0x4e/0x74) 3.465633 <0000000000104760> cpu_idle+0x170/0x184 3.465636 <00000000005b5182> smp_start_secondary+0xd6/0xe0 3.465641 <00000000005c86be> restart_int_handler+0x56/0x6c 3.465643 <0000000000000000> 0x0 3.465645 Last Breaking-Event-Address: 3.465647 <0000000000403136> tty_wakeup+0x46/0x98 3.465652 3.465654 Kernel panic - not syncing: Fatal exception in interrupt 01: HCPGIR450W CP entered; disabled wait PSW 00020001 80000000 00000000 0010F63C The easiest solution is simply to check if tty is NULL in the tasklet. If it is NULL nothing is to do (no tty attached), otherwise tty_wakeup() can be called, since we hold a reference to the tty. This is not nice... but it is a small patch and it works. Signed-off-by: Heiko Carstens Signed-off-by: Martin Schwidefsky 囷ɑAx