kern/57371: Automated test fs/vfs/t_vnops:nfs_rename_reg_nodir fails intermittently on Rpi3 and Rpi4

[jspath55%gmail.com@localhost]

>Number:         57371
>Category:       kern
>Synopsis:       Automated test fs/vfs/t_vnops:nfs_rename_reg_nodir fails intermittently on Rpi3 and Rpi4
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Wed Apr 19 21:30:00 +0000 2023
>Originator:     Jim Spath
>Release:        10.0_BETA
>Organization:
>Environment:
NetBSD nb4 10.0_BETA NetBSD 10.0_BETA (GENERIC64) #0: Fri Jan 13 19:15:32 UTC 2023  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/evbarm/compile/GENERIC64 evbarm

>Description:
After seeing a pass then a failure for the test case, I ran it alone frequently and found intermittent failures.

cd /usr/tests
atf-run fs/vfs/t_vnops:nfs_rename_reg_nodir

Example failure message

tc-end: 1681852322.816669, nfs_rename_reg_nodir, failed, /usr/src/tests/fs/vfs/t_vnops.c:486: sb.st_nlink != 1



More lines from a failure:
tc-se:Here we go.
tc-se:can't register with udp6 portmap
tc-se:can't register with tcp6 portmap
tc-se:got mount request from 10.3.2.2
tc-se:-> rpcpath: /myexport
tc-se:-> dirpath: /myexport
tc-se:Mount successful.
tc-so:[   1.0000000] entropy: ready
tc-so:[   1.0200050] ZFS filesystem version: 5
tc-so:[   1.4500050] 10.3.2.1:/myexport: inaccurate wcc data (ctime) detected, disabling wcc (ctime 1681912801.213091809 1681912801.213091809, mtime 1681912801.213091809 1681912801.213091809)
tc-end: 1681912801.324130, nfs_rename_reg_nodir, failed, /usr/src/tests/fs/vfs/t_vnops.c:486: sb.st_nlink != 1
tp-end: 1681912801.324689, fs/vfs/t_vnops
info: time.end, Wed Apr 19 14:00:01 UTC 2023


Other lines from a pass:
tc-se:Getting mount list.
tc-se:Here we go.
tc-se:can't register with udp6 portmap
tc-se:can't register with tcp6 portmap
tc-se:got mount request from 10.3.2.2
tc-se:-> rpcpath: /myexport
tc-se:-> dirpath: /myexport
tc-se:Mount successful.
tc-so:[   1.0000000] entropy: ready
tc-so:[   1.0200050] ZFS filesystem version: 5
tc-so:[   1.5700050] 10.3.2.1:/myexport: inaccurate wcc data (ctime) detected, disabling wcc (ctime 1681913161.729552120 1681913161.729552120, mtime 1681913161.729552120 1681913161.729552120)
tc-end: 1681913162.432160, nfs_rename_reg_nodir, passed
tp-end: 1681913162.432711, fs/vfs/t_vnops
info: time.end, Wed Apr 19 14:06:02 UTC 2023

>How-To-Repeat:
The failure occurs only a few percentage of the runs I have done:

$ grep tc-end t_vnops.log | wc -l
      21
$ grep tc-end t_vnops.log | grep passed | wc -l
      20

>Fix:
Unknown.