The Nightly test failure in test_integration/test_smb.py::TestSMB::test_ntlm_authentication*
test_ntlm_authentication_with_auto_domain
test_ntlm_authentication_with_upn_with_lowercase_domain
test_ntlm_authentication_with_upn_with_uppercase_domain started failing.
These tests are failing for repeated smb mount

Steps to Reproduce:

1. Star topology: IPA master + 2 IPA clients + 1 AD domain with two-way trust
2. AD trust installed and configured (ipa-adtrust-install, DNS, trust with AD)
3. IPA users user1 and user2 created with home directories on client1
4. ipa-client-samba -U on client1; smb and winbind enabled and running
5. No Kerberos ticket on client2 (kdestroy -A)

test_ntlm_authentication_with_auto_domain

On client2 (smbclient), destroy Kerberos credentials:
kdestroy -A
On client1 (smbserver), create a test file in the user's home:
touch /home/user1/ntlm_test
On client2, create mount point and mount with NTLM + automatic domain discovery:
mkdir -p /mnt/smb
mount -t cifs //client1.ufreeipa.test/homes /mnt/smb -o user=user1,pass=SecretUser1,domainauto
Verify the test file is visible, unmount, and repeat steps 4–5 a second time.

Expected Behavior

Both mount attempts succeed (return code 0).
/mnt/smb/ntlm_test exists after each mount.
umount /mnt/smb succeeds between iterations.

Actual Behavior

First mount fails immediately:
mount error(5): Input/output error
Refer to the mount.cifs(8) manual page (e.g. man mount.cifs) and kernel log messages (dmesg)
Exit code: 32
Share is never mounted; second iteration is never reached.
Assertion at check_repeated_smb_mount() line 410: Mount failed at iteration 1. Output: mount error(5): Input/output error

test_ntlm_authentication_with_upn_with_lowercase_domain

On client2, run kdestroy -A.
On client1, create /home/user1/ntlm_test.
On client2, mount using UPN with lowercase domain:
mkdir -p /mnt/smb
mount -t cifs //client1.ufreeipa.test/homes /mnt/smb -o user=user1@ufreeipa.test,pass=SecretUser1
Verify /mnt/smb/ntlm_test exists, unmount, and repeat mount once more.

Expected Behavior

Both NTLM mounts with user1@ufreeipa.test succeed.
Test file is accessible after each mount.
Mount/unmount cycle works twice without error.

Actual Behavior

First mount fails with the same error:
mount error(5): Input/output error
Exit code: 32
/mnt/smb is not mounted (umount: /mnt/smb: not mounted on cleanup).

test_ntlm_authentication_with_upn_with_uppercase_domain

On client2, run kdestroy -A.
On client1, create /home/user1/ntlm_test.
On client2, mount using UPN with uppercase domain:
mkdir -p /mnt/smb
mount -t cifs //client1.ufreeipa.test/homes /mnt/smb -o user=user1@UFREEIPA.TEST,pass=SecretUser1
Verify /mnt/smb/ntlm_test exists, unmount, and repeat mount once more.

Expected Behavior

Both NTLM mounts with user1@UFREEIPA.TEST succeed (case-insensitive domain handling).
Test file is accessible after each mount.
Repeated mount/unmount works reliably.

Actual Behavior

First mount fails identically:
mount error(5): Input/output error
Exit code: 32
No file access; mount never succeeds.

Additional info:
Logs available in https://ARTIFACTS_SERVER/idm-ci/freeipa_upstream_nightly/Nightly-latest/master/2026-05-30_05-11/latest/test_smb/1/report.html?sort=result
Failing on :
freeipa-server-4.14.0.dev202605281228+git5e033abeb-0.fc44.x86_64
samba-4.24.2-1.fc44.x86_64
Last passed using :
samba-4.24.1-1.fc44.x86_64
freeipa-server-4.14.0.dev202605121751+git564db1017-0.fc44.x86_64
https://ARTIFACTS_SERVER/idm-ci/freeipa_upstream_nightly/Nightly-latest/master/2026-05-16_04-56/latest/test_smb/1/