Public bug reported: Cisco UCS C220 M7N (ASPEED BMC VGA, ast driver), 2x Xeon Platinum 8562Y+, Ubuntu 26.04.1, 7.0.0-38-generic, systemd 259.5-0ubuntu3.4. Headless; console only via the BMC KVM.
From 03:23 UTC the hung-task detector reports kworker/18:2 (drm_fb_helper_damage_work) blocked in mutex_lock from drm_fb_helper_fb_dirty, and names the likely owner: kworker/1:2, state R, in output_poll_execute -> ast_vga_connector_helper_detect_ctx -> drm_connector_helper_detect_from_ddc -> drm_probe_ddc -> i2c_transfer -> bit_xfer -> try_address -> yield. The same owner is reported for 15 minutes, until the hung-task warning limit is used up. khugepaged is also blocked in lru_add_drain_all -> flush_work from 03:36. Effects: the BMC KVM console stopped updating at 03:23. About 3 h later a user manager ([email protected]) hung at start and survived SIGKILL, and systemd (PID 1) hung in a daemon-reload, so systemctl failed with "Transport endpoint is not connected". Recovered only by a BMC reset. No hung-task reports for those later tasks, since the limit was used up. Release: Ubuntu 26.04.1 LTS, kernel package 7.0.0-38.38 (version_signature and lspci -vnvn attached). Expected: the VGA connector poll finishes or gives up, and the console and other kernel work keep running. Happened once so far, not reproduced. The console gets a steady stream of log lines from a containerized application. Kernel log of the affected boot attached, with hostnames and addresses replaced. ** Affects: linux (Ubuntu) Importance: Undecided Status: New ** Tags: amd64 resolute ** Attachment added: "Kernel log of the affected boot (hostnames and addresses replaced)" https://bugs.launchpad.net/bugs/2170947/+attachment/6009382/+files/hang-kernel.public.log -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/2170947 Title: ast: VGA connector poll (DDC probe over i2c_algo_bit) never finishes, holds DRM lock; console frozen, lru_add_drain_all hangs (7.0.0-38) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2170947/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
