settimeofday01 in ubuntu_ltp_syscalls failed on KVM kernels

[Po-Hsu Lin]

Issue found on C-KVM, from the test case content, these two tests are:
 * Call settimeofday and verify the time was changed.
 * Call settimeofday with invalid Args and verify that the call fails.

<<<test_start>>>
tag=settimeofday01 stime=1561358482
cmdline="settimeofday01"
contacts=""
analysis=exit
<<<test_output>>>
settimeofday01 1 TFAIL : settimeofday01.c:124: Test condition 1 failed
settimeofday01 2 TPASS : Test condition 2 successful
<<<execution_status>>>
initiation_status="ok"
duration=0 termination_type=exited termination_id=1 corefile=no
cutime=0 cstime=0
<<<test_end>>>

ProblemType: Bug
DistroRelease: Ubuntu 18.10
Package: linux-image-4.18.0-1015-kvm 4.18.0-1015.15
ProcVersionSignature: User Name 4.18.0-1015.15-kvm 4.18.20
Uname: Linux 4.18.0-1015-kvm x86_64
ApportVersion: 2.20.10-0ubuntu13.3
Architecture: amd64
Date: Mon Jun 24 06:41:26 2019
SourcePackage: linux-kvm
UpgradeStatus: No upgrade log present (probably fresh install)

[Po-Hsu Lin (cypressyew)]

It looks like if we run this test repeatedly, most of the time it will pass:

$ sudo ./settimeofday01 -i 1000 | grep FAIL | wc -l
10
$ sudo ./settimeofday01 -i 1000 | grep FAIL | wc -l
8
$ sudo ./settimeofday01 -i 1000 | grep FAIL | wc -l
10

This might be able to explain why sometimes we cannot see this failure in the test report.
Not sure what is the cause of this

[Po-Hsu Lin (cypressyew)]

Spotted on kvm-4.15.0-1028 as well.

[Kai-Heng Feng (kaihengfeng)]

Not seeing this issue on Bionic guest w/ 4.15-kvm inside Bionic host w/ v4.15-generic host.:
$ sudo ./testcases/kernel/syscalls/settimeofday/settimeofday01 -i 10000000 | grep FAIL | wc -l
0

Maybe the host in question is also flaky?

[Po-Hsu Lin (cypressyew)]

* Tested with the 4.15 generic kernel on the KVM node, test failed
* Tested with the 4.4 generic kernel on the KVM host, test passed with 10000000 iterations.

[Kai-Heng Feng (kaihengfeng)]

I'll find a system to test both 4.4 and 4.15 to make sure it's not hardware related.

[Po-Hsu Lin (cypressyew)]

Issue could be found on 5.0 GCP, instance "f1-micro"

[Kai-Heng Feng (kaihengfeng)]

I tried different combinations of host/guest kernels, but I don't see this issue.

Are "KVM node" and "KVM host" referred in comment #5 different?

[Po-Hsu Lin (cypressyew)]

Hi,

I think the KVM host referred here is our KVM pod (bare metal), and the KVM node is a KVM instance created on that pod.

We have the host upgraded to 4.15 recently, let me see if I can try this again.

[Po-Hsu Lin (cypressyew)]

Passed with:
* 4.15 KVM
* 5.3 KVM
* 4.4 KVM

with the fix to turn timesyncd off:
https://kernel.ubuntu.com/git/ubuntu/autotest-client-tests.git/commit/ubuntu_ltp_syscalls?id=2ee96043fde8ba46658f1ef89d10365bfd9457bb

Thanks!