Public bug reported:
SRU cycle: 2026.10.12
Kernel: linux-azure-fde-5.15 5.15.0-1124.133~20.04.1
Cloud: azure
Instance types: Standard_DC2as_v5, Standard_DC8ads_v5, Standard_EC2as_v6,
Standard_EC8ads_v6
Test suite: ubuntu_lxc
Failed sub-tests: lxc-test-apparmor-mount, lxc-test-unpriv
Description:
Both LXC sub-tests fail consistently on all 4 AMD Confidential Computing (CC)
Azure instances. The failure mechanism is identical across all instances:
1. lxc-start fails with "Received container state ABORTING instead of RUNNING"
2. Container cannot allocate new network namespace ID: "Operation not
permitted"
3. Container cannot mount proc: "Failed to mount proc onto
/usr/lib/x86_64-linux-gnu/lxc/proc"
4. umount of /sys/kernel/security/apparmor/features/mount fails: "not mounted"
Root cause:
Unprivileged namespace and proc-mount restrictions on AMD CC instances
prevent LXC containers from starting properly.
Important note:
Historical "passes" for these tests were FAKE. Comparing 5.15.0-1102.111
(last "passed") against current versions shows:
- "Passed" runs: lxc-start failed with "The container failed to start" but
the test script printed "PASS" unconditionally (exit-code bug in test
script)
- Current runs: lxc-start fails with proper error propagation, causing
non-zero exit and correct test failure
The visible pass -> fail flip at 5.15.0-1103.112 is a test script artifact,
NOT a kernel regression. The underlying issue (LXC broken on AMD CC) has
existed since at least 5.15.0-1102.
Test runs demonstrating the issue:
- Run 3383984 (DC2as_v5)
- Run 3388914 (DC8ads_v5)
- Run 3383988 (EC2as_v6)
- Run 3388605 (EC8ads_v6)
Expected behavior:
LXC containers should start successfully on AMD CC instances, or the test
should properly skip/mark these configurations as unsupported.
Actual behavior:
LXC container start fails due to namespace/mount restrictions.
** Affects: linux-azure-fde-5.15 (Ubuntu)
Importance: Undecided
Status: New
** Affects: linux-azure-fde-5.15 (Ubuntu Focal)
Importance: Undecided
Status: New
** Affects: linux-azure-fde-5.15 (Ubuntu Jammy)
Importance: Undecided
Status: New
** Also affects: linux-azure-fde-5.15 (Ubuntu Jammy)
Importance: Undecided
Status: New
** Also affects: linux-azure-fde-5.15 (Ubuntu Focal)
Importance: Undecided
Status: New
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https://bugs.launchpad.net/bugs/2171590
Title:
ubuntu_lxc: lxc-test-apparmor-mount and lxc-test-unpriv fail on AMD CC
instances (azure-fde-5.15)
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