This is only being seen with ZFS, and only started on 2019-08-21:
https://testing.whamcloud.com/test_sets/6cbefd98-c448-11e9-a2b6-52540065bddc
There were a bunch of landings to master on that date, in particular patch https://review.whamcloud.com/34951 "LU-12336 build: Update ZFS version to 0.8.1" (previously ZFS 0.7.13 was used). It isn't clear if the missing space is a "leak" or if that just represents some internal ZFS data structure that is now being allocated that didn't previously exist and is normal behaviour? The sizes reported in test failures is usually the same (309264KB - 307632KB = 1632KB, but there was one failure (of 10 so far) that reported 35840KB - 32768KB = 3072KB.
One way to determine if this is a leak or not would be to run runtests several times in a row on the same filesystem, and see if each one is reporting a leak, or if that is only seen on the first one run? It appears that runtests is the first test run after the filesystem is formatted, so it may be that there is some space allocated when the filesystem is first used.
"Oleg Drokin <green@whamcloud.com>" merged in patch https://review.whamcloud.com/45579/
Subject:
LU-12579tests: allow some margin in runtestsProject: fs/lustre-release
Branch: b2_12
Current Patch Set:
Commit: fac5c55ac3ec550030c0885e8449c823c983aad0