btw., i'm seeing a boot hang too, with the attached config:

PM: Adding info for platform:serial8250
serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
device: 'ttyS0': device_add
PM: Adding info for No Bus:ttyS0
INFO: rcu_sched_state detected stalls on CPUs/tasks: { 0} (detected by 1, t=6002 jiffies)
INFO: rcu_sched_state detected stalls on CPUs/tasks: { 0} (detected by 1, t=24034 jiffies)
INFO: rcu_sched_state detected stalls on CPUs/tasks: { 0} (detected by 1, t=42066 jiffies)
INFO: rcu_sched_state detected stalls on CPUs/tasks: { 0} (detected by 1, t=6002 jiffies)
INFO: rcu_sched_state detected stalls on CPUs/tasks: { 0} (detected by 1, t=24034 jiffies)

(and the stall warnings go on forever)

Thanks,

	Ingo