I'm not sure if this is specific to snowball, or even if it is related to bluetooth. I just hit a backtrace that appears to be the same  on a pandaboard after transferring a file over USB and letting it sit idle for a few minutes with an open adb shell connection:
[ 1178.132659] INFO: rcu_preempt detected stalls on CPUs/tasks: { 0} (detected by 1, t=7682 jiffies)
[ 1178.141998] Backtrace for cpu 1 (current):
[ 1178.146331] [<c0019fb4>] (unwind_backtrace+0x0/0xf8) from [<c00183bc>] (smp_send_all_cpu_backtrace+0x5c/0xc0)
[ 1178.156799] [<c00183bc>] (smp_send_all_cpu_backtrace+0x5c/0xc0) from [<c008a7b4>] (__rcu_pending+0x39c/0x418)
[ 1178.167236] [<c008a7b4>] (__rcu_pending+0x39c/0x418) from [<c008b360>] (rcu_check_callbacks+0x194/0x2a4)
[ 1178.177215] [<c008b360>] (rcu_check_callbacks+0x194/0x2a4) from [<c0052dc4>] (update_process_times+0x38/0x4c)
[ 1178.187683] [<c0052dc4>] (update_process_times+0x38/0x4c) from [<c0071804>] (tick_sched_timer+0x88/0xd8)
[ 1178.197662] [<c0071804>] (tick_sched_timer+0x88/0xd8) from [<c0065b14>] (__run_hrtimer+0x7c/0x278)
[ 1178.207092] [<c0065b14>] (__run_hrtimer+0x7c/0x278) from [<c0066900>] (hrtimer_interrupt+0x114/0x2a0)
[ 1178.216796] [<c0066900>] (hrtimer_interrupt+0x114/0x2a0) from [<c0018c14>] (twd_handler+0x30/0x44)
[ 1178.226226] [<c0018c14>] (twd_handler+0x30/0x44) from [<c0086b44>] (handle_percpu_devid_irq+0x90/0x180)
[ 1178.236145] [<c0086b44>] (handle_percpu_devid_irq+0x90/0x180) from [<c0083434>] (generic_handle_irq+0x28/0x3c)
[ 1178.246673] [<c0083434>] (generic_handle_irq+0x28/0x3c) from [<c0014298>] (handle_IRQ+0x4c/0xb0)
[ 1178.255950] [<c0014298>] (handle_IRQ+0x4c/0xb0) from [<c06288f4>] (__irq_svc+0x34/0xac)
[ 1178.264343] [<c06288f4>] (__irq_svc+0x34/0xac) from [<c0628484>] (__raw_spin_lock_irqsave+0x88/0xa8)
[ 1178.273986] [<c0628484>] (__raw_spin_lock_irqsave+0x88/0xa8) from [<bf0141fc>] (st_unregister+0x38/0x144 [st_drv])
[ 1178.284881] [<bf0141fc>] (st_unregister+0x38/0x144 [st_drv]) from [<bf06b04c>] (ti_st_close+0x3c/0x84 [btwilink])
[ 1178.295806] [<bf06b04c>] (ti_st_close+0x3c/0x84 [btwilink]) from [<bf01f84c>] (hci_dev_do_close+0x104/0x1e4 [bluetooth])
[ 1178.307281] [<bf01f84c>] (hci_dev_do_close+0x104/0x1e4 [bluetooth]) from [<bf0202e8>] (hci_dev_close+0x14/0x68 [bluetooth])
[ 1178.319061] [<bf0202e8>] (hci_dev_close+0x14/0x68 [bluetooth]) from [<bf02bfbc>] (hci_sock_ioctl+0x190/0x3cc [bluetooth])
[ 1178.330596] [<bf02bfbc>] (hci_sock_ioctl+0x190/0x3cc [bluetooth]) from [<c04a8b14>] (sock_ioctl+0x70/0x264)
[ 1178.340850] [<c04a8b14>] (sock_ioctl+0x70/0x264) from [<c00e7404>] (do_vfs_ioctl+0x80/0x534)
[ 1178.349731] [<c00e7404>] (do_vfs_ioctl+0x80/0x534) from [<c00e7924>] (sys_ioctl+0x6c/0x7c)
[ 1178.358428] [<c00e7924>] (sys_ioctl+0x6c/0x7c) from [<c00133a0>] (ret_fast_syscall+0x0/0x30)
[ 1178.367309] 
[ 1178.367309] sending IPI to all other CPUs:
[ 1358.382690] INFO: rcu_preempt detected stalls on CPUs/tasks: { 0} (detected by 1, t=30754 jiffies)
[ 1358.392120] Backtrace for cpu 1 (current):
[ 1358.396453] [<c0019fb4>] (unwind_backtrace+0x0/0xf8) from [<c00183bc>] (smp_send_all_cpu_backtrace+0x5c/0xc0)
[ 1358.406890] [<c00183bc>] (smp_send_all_cpu_backtrace+0x5c/0xc0) from [<c008a7b4>] (__rcu_pending+0x39c/0x418)
[ 1358.417327] [<c008a7b4>] (__rcu_pending+0x39c/0x418) from [<c008b360>] (rcu_check_callbacks+0x194/0x2a4)
[ 1358.427337] [<c008b360>] (rcu_check_callbacks+0x194/0x2a4) from [<c0052dc4>] (update_process_times+0x38/0x4c)
[ 1358.437774] [<c0052dc4>] (update_process_times+0x38/0x4c) from [<c0071804>] (tick_sched_timer+0x88/0xd8)
[ 1358.447753] [<c0071804>] (tick_sched_timer+0x88/0xd8) from [<c0065b14>] (__run_hrtimer+0x7c/0x278)
[ 1358.457214] [<c0065b14>] (__run_hrtimer+0x7c/0x278) from [<c0066900>] (hrtimer_interrupt+0x114/0x2a0)
[ 1358.466918] [<c0066900>] (hrtimer_interrupt+0x114/0x2a0) from [<c0018c14>] (twd_handler+0x30/0x44)
[ 1358.476348] [<c0018c14>] (twd_handler+0x30/0x44) from [<c0086b44>] (handle_percpu_devid_irq+0x90/0x180)
[ 1358.486236] [<c0086b44>] (handle_percpu_devid_irq+0x90/0x180) from [<c0083434>] (generic_handle_irq+0x28/0x3c)
[ 1358.496795] [<c0083434>] (generic_handle_irq+0x28/0x3c) from [<c0014298>] (handle_IRQ+0x4c/0xb0)
[ 1358.506042] [<c0014298>] (handle_IRQ+0x4c/0xb0) from [<c06288f4>] (__irq_svc+0x34/0xac)
[ 1358.514465] [<c06288f4>] (__irq_svc+0x34/0xac) from [<c062847c>] (__raw_spin_lock_irqsave+0x80/0xa8)
[ 1358.524108] [<c062847c>] (__raw_spin_lock_irqsave+0x80/0xa8) from [<bf0141fc>] (st_unregister+0x38/0x144 [st_drv])
[ 1358.535003] [<bf0141fc>] (st_unregister+0x38/0x144 [st_drv]) from [<bf06b04c>] (ti_st_close+0x3c/0x84 [btwilink])
[ 1358.545837] [<bf06b04c>] (ti_st_close+0x3c/0x84 [btwilink]) from [<bf01f84c>] (hci_dev_do_close+0x104/0x1e4 [bluetooth])
[ 1358.557342] [<bf01f84c>] (hci_dev_do_close+0x104/0x1e4 [bluetooth]) from [<bf0202e8>] (hci_dev_close+0x14/0x68 [bluetooth])
[ 1358.569091] [<bf0202e8>] (hci_dev_close+0x14/0x68 [bluetooth]) from [<bf02bfbc>] (hci_sock_ioctl+0x190/0x3cc [bluetooth])
[ 1358.580657] [<bf02bfbc>] (hci_sock_ioctl+0x190/0x3cc [bluetooth]) from [<c04a8b14>] (sock_ioctl+0x70/0x264)
[ 1358.590911] [<c04a8b14>] (sock_ioctl+0x70/0x264) from [<c00e7404>] (do_vfs_ioctl+0x80/0x534)
[ 1358.599822] [<c00e7404>] (do_vfs_ioctl+0x80/0x534) from [<c00e7924>] (sys_ioctl+0x6c/0x7c)
[ 1358.608520] [<c00e7924>] (sys_ioctl+0x6c/0x7c) from [<c00133a0>] (ret_fast_syscall+0x0/0x30)
[ 1358.617401] 
[ 1358.617401] sending IPI to all other CPUs:
[ 1538.632690] INFO: rcu_preempt detected stalls on CPUs/tasks: { 0} (detected by 1, t=53826 jiffies)
[ 1538.642120] Backtrace for cpu 1 (current):
[ 1538.646453] [<c0019fb4>] (unwind_backtrace+0x0/0xf8) from [<c00183bc>] (smp_send_all_cpu_backtrace+0x5c/0xc0)
[ 1538.656890] [<c00183bc>] (smp_send_all_cpu_backtrace+0x5c/0xc0) from [<c008a7b4>] (__rcu_pending+0x39c/0x418)
[ 1538.667327] [<c008a7b4>] (__rcu_pending+0x39c/0x418) from [<c008b360>] (rcu_check_callbacks+0x194/0x2a4)
[ 1538.677337] [<c008b360>] (rcu_check_callbacks+0x194/0x2a4) from [<c0052dc4>] (update_process_times+0x38/0x4c)
[ 1538.687774] [<c0052dc4>] (update_process_times+0x38/0x4c) from [<c0071804>] (tick_sched_timer+0x88/0xd8)
[ 1538.697753] [<c0071804>] (tick_sched_timer+0x88/0xd8) from [<c0065b14>] (__run_hrtimer+0x7c/0x278)
[ 1538.707183] [<c0065b14>] (__run_hrtimer+0x7c/0x278) from [<c0066900>] (hrtimer_interrupt+0x114/0x2a0)
[ 1538.716918] [<c0066900>] (hrtimer_interrupt+0x114/0x2a0) from [<c0018c14>] (twd_handler+0x30/0x44)
[ 1538.726348] [<c0018c14>] (twd_handler+0x30/0x44) from [<c0086b44>] (handle_percpu_devid_irq+0x90/0x180)
[ 1538.736236] [<c0086b44>] (handle_percpu_devid_irq+0x90/0x180) from [<c0083434>] (generic_handle_irq+0x28/0x3c)
[ 1538.746795] [<c0083434>] (generic_handle_irq+0x28/0x3c) from [<c0014298>] (handle_IRQ+0x4c/0xb0)
[ 1538.756042] [<c0014298>] (handle_IRQ+0x4c/0xb0) from [<c06288f4>] (__irq_svc+0x34/0xac)
[ 1538.764465] [<c06288f4>] (__irq_svc+0x34/0xac) from [<c062847c>] (__raw_spin_lock_irqsave+0x80/0xa8)
[ 1538.774108] [<c062847c>] (__raw_spin_lock_irqsave+0x80/0xa8) from [<bf0141fc>] (st_unregister+0x38/0x144 [st_drv])
[ 1538.785003] [<bf0141fc>] (st_unregister+0x38/0x144 [st_drv]) from [<bf06b04c>] (ti_st_close+0x3c/0x84 [btwilink])
[ 1538.795837] [<bf06b04c>] (ti_st_close+0x3c/0x84 [btwilink]) from [<bf01f84c>] (hci_dev_do_close+0x104/0x1e4 [bluetooth])
[ 1538.807342] [<bf01f84c>] (hci_dev_do_close+0x104/0x1e4 [bluetooth]) from [<bf0202e8>] (hci_dev_close+0x14/0x68 [bluetooth])
[ 1538.819091] [<bf0202e8>] (hci_dev_close+0x14/0x68 [bluetooth]) from [<bf02bfbc>] (hci_sock_ioctl+0x190/0x3cc [bluetooth])
[ 1538.830657] [<bf02bfbc>] (hci_sock_ioctl+0x190/0x3cc [bluetooth]) from [<c04a8b14>] (sock_ioctl+0x70/0x264)
[ 1538.840911] [<c04a8b14>] (sock_ioctl+0x70/0x264) from [<c00e7404>] (do_vfs_ioctl+0x80/0x534)
[ 1538.849822] [<c00e7404>] (do_vfs_ioctl+0x80/0x534) from [<c00e7924>] (sys_ioctl+0x6c/0x7c)
[ 1538.858520] [<c00e7924>] (sys_ioctl+0x6c/0x7c) from [<c00133a0>] (ret_fast_syscall+0x0/0x30)
[ 1538.867401] 
[ 1538.867401] sending IPI to all other CPUs: