Consistent ZTS failures on Linux/ppc64

[rincebrain]

System information

Type	Version/Name
Distribution Name	Debian
Distribution Version	sid
Linux Kernel	5.10.0-6-powerpc64
Architecture	ppc64
ZFS Version	7457b02

Describe the problem you're observing

The following 3 ZTS tests fail every time I've tried on Linux/ppc64 and Linux/sparc64:
rsend/recv_dedup
rsend/recv_dedup_encrypted_zvol
cli_root/zdb/zdb_005_pos

(I'll probably look into this if nobody else gets to it before I have more time, I just wanted to report it before I forgot.)

Describe how to reproduce the problem

Run those tests individually or in a runfile group, I think.

Include any warning/errors/backtraces from the system logs

Attached. (The logs are from a run of the branch from PR #12022 , but it reproduces with identical log messages on vanilla, this just happened to be the error logs I grabbed first.)
ppc64_test.zip

[stale]

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