log_check test in ubuntu_boot will erroneously get error from previous session on manually provisioned systems

[Po-Hsu Lin]

Issue found on s390x node s2lp4, the log_check test erroneously report the error message reported in earlier runs (the uptime here is too old for a fresh reboot)

07:32:35 INFO | kernel: [196220.210597] BUG: non-zero pgtables_bytes on freeing mm: 16384
07:32:35 INFO | kernel: [196220.227126] BUG: non-zero pgtables_bytes on freeing mm: 16384
07:32:35 INFO | kernel: [196220.227476] BUG: non-zero pgtables_bytes on freeing mm: 16384
07:32:35 INFO | kernel: [196220.276436] BUG: non-zero pgtables_bytes on freeing mm: 16384
07:32:35 INFO | kernel: [196220.276775] BUG: non-zero pgtables_bytes on freeing mm: 16384

This is because we parse log from syslog. It's ok on other ones because they all got re-provisioned.

dmesg will be cleared out in autotest with dmesg -c before the test starts.

We need to find another way to get the boot dmesg

[Po-Hsu Lin (cypressyew)]

https://lists.ubuntu.com/archives/kernel-team/2021-August/122912.html

[Po-Hsu Lin (cypressyew)]

Trying to fix this for infrastructure tool side instead.

[Po-Hsu Lin (cypressyew)]

Fix landed in CKCT by rotating the syslog before the test.