bl iks: cpu hotplug test popping up unwind errors

while running bl iks cpu hotplug test,
kernel popping up following messages

test execution:
root@android:/ # run_stress_switcher_tests.sh -b

bL IKS build:
https://snapshots.linaro.org/android/~linaro-android-restricted/vexpress-linaro-iks/121/

Test log:
---------
https://pastebin.linaro.org/1773/
https://pastebin.linaro.org/1774/

Linux kernel:
Linux localhost 3.7.6-00695-gca4da8e #1 SMP Thu Feb 21 00:30:16 UTC 2013 armv7

kernel commit id:
ca4da8edf024b964d679d0a2843399cf5afa9398

kernel messages:
----------------
[ 4128.929636] sending IPI to all other CPUs:
[ 4128.946617] IPI backtrace for cpu 2
[ 4128.957061]
[ 4128.961500] Pid: 0, comm: swapper/2
[ 4128.974794] CPU: 2 Tainted: G W (3.7.6-00695-gca4da8e #1)
[ 4128.994605] PC is at tc2_enter_powerdown+0x6c/0xd0
[ 4129.008944] LR is at getnstimeofday+0x4c/0x12c
[ 4129.022238] pc : [<c001fe48>] lr : [<c0063370>] psr: 20000153
[ 4129.022238] sp : ef095f70 ip : 41188739 fp : c05a7ee8
[ 4129.056627] r10: c0583148 r9 : c05a7f74 r8 : 00000002
[ 4129.072264] r7 : c05ead04 r6 : 00000001 r5 : c16132cc r4 : c16132c8
[ 4129.091806] r3 : 00000000 r2 : 1707eccd r1 : 00000000 r0 : 3b9ac9ff
[ 4129.111350] Flags: nzCv IRQs on FIQs off Mode SVC_32 ISA ARM Segment kel
[ 4129.133497] Control: 10c5387d Table: aeb9406a DAC: 00000015
[ 4129.150695]
[ 4129.150695] PC: 0xc001fdc8:

[ 4313.774574] [<c000ee98>] (cpu_idle+0x9c/0x104) from [<803c5b48>] (0x803c5b48)