cpu_hotplug test failed due to Permission denied

[Po-Hsu Lin]

Node: Standard_D11_v2
Kernel: 4.18.0-1008.8~18.04.1

 TAP version 13
 selftests: cpu-hotplug: cpu-on-off-test.sh
 ========================================
 pid 9047's current affinity mask: 3
 pid 9047's new affinity mask: 1
 CPU online/offline summary:
 present_cpus = 0-1 present_max = 1
 Cpus in online state: 0-1
 Cpus in offline state: 2-127
 Limited scope test: one hotplug cpu
 (leaves cpu in the original state):
 online to offline to online: cpu 1
19. 01/30 19:57:02 ERROR| utils:0153| [stderr] ./cpu-on-off-test.sh: line 96: /sys/devices/system/cpu/cpu1/online: Permission denied
20. 01/30 19:57:02 ERROR| utils:0153| [stderr] offline_cpu_expect_success 1: unexpected fail
 not ok 1..1 selftests: cpu-hotplug: cpu-on-off-test.sh [FAIL]

[Po-Hsu Lin (cypressyew)]

This will need to CONFIG_HOTPLUG_CPU=y, which was not set on Azure kernel.

Will try to fix this upstream.

[Po-Hsu Lin (cypressyew)]

BTW, the CONFIG_HOTPLUG_CPU for azure was disabled in bug 1776293

[Po-Hsu Lin (cypressyew)]

CPU hotplug for Azure has been enabled in https://bugs.launchpad.net/ubuntu/+source/linux-azure/+bug/1821934

[Po-Hsu Lin (cypressyew)]

Failed on AWS X-4.15 ARM64 (it's only failing on ARM64)

[Po-Hsu Lin (cypressyew)]

BTW it's instance a1.large, and the error message is a bit different:

 selftests: cpu-on-off-test.sh
 ========================================
 pid 19403's current affinity mask: 3
 pid 19403's new affinity mask: 1
 CPU online/offline summary:
 present_cpus = 0-1 present_max = 1
 Cpus in online state: 0-1
 Cpus in offline state: 0
 Limited scope test: one hotplug cpu
 (leaves cpu in the original state):
 online to offline to online: cpu 1
 ./cpu-on-off-test.sh: line 89: echo: write error: Input/output error
 online_cpu_expect_success 1: unexpected fail
 not ok 1..1 selftests: cpu-on-off-test.sh [FAIL]

[Kelsey Steele (kelsey-steele)]

focal/hwe-5.8 : 5.8.0-51.57~20.04.1

21. 04/24 04:59:10 DEBUG| utils:0153| [stdout] # Limited scope test: one hotplug cpu
22. 04/24 04:59:10 DEBUG| utils:0153| [stdout] # (leaves cpu in the original state):
23. 04/24 04:59:10 DEBUG| utils:0153| [stdout] # online to offline to online: cpu 7
24. 04/24 04:59:10 DEBUG| utils:0153| [stdout] # ./cpu-on-off-test.sh: line 96: /sys/devices/system/cpu/cpu7/online: Permission denied
25. 04/24 04:59:10 DEBUG| utils:0153| [stdout] # offline_cpu_expect_success 7: unexpected fail
26. 04/24 04:59:10 DEBUG| utils:0153| [stdout] not ok 1 selftests: cpu-hotplug: cpu-on-off-test.sh # exit=1