Public bug reported:
[Impact]
On linux-image-6.8.0-134-generic the AMD IOMMU (AMD-Vi) begins logging
"AMD-Vi: Completion-Wait loop timed out" within hours of boot, and the machine
then hard-freezes every 3-6 days requiring a physical power cycle: no SSH, dead
console, no clean shutdown recorded. The final kernel log line before each
freeze
is that AMD-Vi timeout.
This is a REGRESSION. The immediately prior kernel, 6.8.0-124-generic, is
completely clean on the same hardware and identical workload.
[Regression evidence: count of "Completion-Wait loop timed out" per boot]
6.8.0-124-generic (Jun 17 -> Jul 4, 17 days) : 0 occurrences, stable
6.8.0-134-generic (Jul 5 -> Jul 11) : 83 occurrences, ended in
hard freeze
6.8.0-134-generic (Jul 11 -> Jul 14) : 43 occurrences, ended in
hard freeze
6.8.0-134-generic (current boot) : 1 occurrence ~18 min
after boot
The errors begin a few hours after booting -134 and accumulate until lockup.
[Hardware]
- Beelink SER5 mini PC
- AMD Ryzen 7 PRO 5850U (Cezanne, integrated Radeon Vega / RENOIR amdgpu)
- 32 GB RAM, BIOS dated 2024-09-06
- No VFIO / PCI passthrough. No custom kernel command line.
- IOMMU default config: "Default domain type: Translated",
"DMA domain TLB invalidation policy: lazy mode".
[Ruled out]
Not OOM (memory healthy, systemd-oomd inactive, zero OOM kills), not disk,
not thermal (the thermal_zone0 read failure appears on the good -124 boots too).
[Steps to reproduce]
1. Boot 6.8.0-134-generic on the above hardware.
2. Run a normal container / desktop workload (rootless podman, amdgpu active).
3. Within hours "AMD-Vi: Completion-Wait loop timed out" appears in dmesg;
within 3-6 days the machine freezes hard.
[Expected]
No IOMMU completion-wait timeouts and no freeze, as on 6.8.0-124-generic.
[Workaround]
Reverting to 6.8.0-124-generic eliminates the errors entirely. "amd_iommu=off"
is expected to also work (no passthrough in use).
[Request]
Please bisect the AMD IOMMU changes between 6.8.0-124 and 6.8.0-134, or advise
if this is a known regression with a fix in flight.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: regression-update
** Attachment added: "Kernel log, 6.8.0-134 boot of Jul 11-14 that ended in a
hard freeze — AMD-Vi Completion-Wait timeouts throughout; final kernel line is
the timeout."
https://bugs.launchpad.net/bugs/2160704/+attachment/5981991/+files/dooku-amdvi-134-prev.txt
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https://bugs.launchpad.net/bugs/2160704
Title:
AMD-Vi "Completion-Wait loop timed out" IOMMU hang → full system
freeze on 6.8.0-134; regression vs 6.8.0-124 (Ryzen 7 PRO 5850U)
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