OOM error on `zpool import -f` despite successful import

[bermudalocket]

System information

Type	Version/Name
Distribution Name	macOS
Distribution Version	11.4 beta (20F5065a)
Linux Kernel	Darwin 20.5.0 (root:xnu-7195.121.3~4/RELEASE_X86_64)
Architecture	x86
ZFS Version	zfs-2.0.0-rc6 (zfs-kmod-zfs-2.0.0-rc1-452-g964b2a6de7)
SPL Version	?

Describe the problem you're observing

Importing a zpool created on Ubuntu (zfs-0.8.3-1ubuntu12.8) throws an out of memory error, but succeeds in importing.

Describe how to reproduce the problem

1. Create a zpool on Ubuntu on a removable device
2. Unmount the device
3. Unplug the device and plug it into the macOS device
4. sudo zpool import -d /dev to discover the pool
5. sudo zpool import <poolname> -f to import

After step 5, an out of memory message will be displayed:

❯ sudo zpool import downloads -f
internal error: out of memory

... but the pool seems to import fine:

❯ sudo zpool list
NAME        SIZE  ALLOC   FREE  CKPOINT  EXPANDSZ   FRAG    CAP  DEDUP    HEALTH  ALTROOT
downloads   464G   288G   176G        -         -    32%    62%  1.00x    ONLINE  -


❯ sudo zpool status downloads
pool: downloads
state: ONLINE
status: Some supported and requested features are not enabled on the pool.
    The pool can still be used, but some features are unavailable.
action: Enable all features using 'zpool upgrade'. Once this is done,
    the pool may no longer be accessible by software that does not support
    the features. See zpool-features(5) for details.
scan: scrub repaired 0B in 00:03:36 with 0 errors on Sun May  9 00:27:46 2021
config:

NAME                                          STATE     READ WRITE CKSUM
downloads                                     ONLINE       0     0     0
  media-CB39844A-1A02-DB44-B898-F37433593365  ONLINE       0     0     0

errors: No known data errors

I'm unsure if the features warning is related to the OOM error, but zpool upgrade also works fine:

❯ sudo zpool status downloads
pool: downloads
state: ONLINE
scan: scrub repaired 0B in 00:03:36 with 0 errors on Sun May  9 00:27:46 2021
config:

NAME                                          STATE     READ WRITE CKSUM
downloads                                     ONLINE       0     0     0
  media-CB39844A-1A02-DB44-B898-F37433593365  ONLINE       0     0     0

errors: No known data errors

Include any warning/errors/backtraces from the system logs

From org.openzfsonosx.zpool-import-all.log:

Mon May 17 16:03:24 EDT 2021
Running zpool import -a
Mon May 17 16:03:36 EDT 2021
Mon May 17 16:03:37 EDT 2021
Launched zpool import -a : 0
Touching the file /var/run/org.openzfsonosx.zpool-import-all.didRun
-zpool-import-all.sh
internal error: out of memory

[ilovezfs]

please try rc7