** Changed in: linux (Ubuntu)
Status: Incomplete => Confirmed
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https://bugs.launchpad.net/bugs/2009594
Title:
Mlx5 kworker blocked Kernel 5.19 (Jammy HWE)
Status in linux package in Ubuntu:
Confirmed
Bug description:
This is seen on particular with :
* Charmed Openstack with Jammy Yoga
* 5.19.0-35-generic (linux-generic-hwe-22.04/jammy-updates)
* Mellanox Connectx-6 card with mlx5_core module being used
* SR-IOV is being used with VF-LAG for the use of OVN hardware offloading
The servers enter into very high load (around 75~100) quickly during the boot
with all process relying on network communication with the Mellanox network
card being stuck or extremely slow.
Kernel logs are being displayed about kworkers being blocked for more than
120 seconds
The number of SR-IOV devices configured both from the firmware and the kernel
seems to have a serious correlation with the likeliness of this bug to occur.
Having enabled more VF seems to hugely increase the risk for this bug to
arise.
This does not happen systematically at every boot, but with 32 VFs on each
PF, it occurs about 40% of the time.
To recover the server, a cold reboot is required.
Look at a quick sample of the trace, this seems to involve directly
the mlx5 driver within the kernel :
Mar 07 05:24:56 nova-1 kernel: INFO: task kworker/0:1:19 blocked for more
than 120 seconds.
Mar 07 05:24:56 nova-1 kernel: Tainted: P OE
5.19.0-35-generic #36~22.04.1-Ubuntu
Mar 07 05:24:56 nova-1 kernel: "echo 0 >
/proc/sys/kernel/hung_task_timeout_secs" disables this message.
Mar 07 05:24:56 nova-1 kernel: task:kworker/0:1 state:D stack: 0 pid:
19 ppid: 2 flags:0x00004000
Mar 07 05:24:56 nova-1 kernel: Workqueue: events work_for_cpu_fn
Mar 07 05:24:56 nova-1 kernel: Call Trace:
Mar 07 05:24:56 nova-1 kernel: <TASK>
Mar 07 05:24:56 nova-1 kernel: __schedule+0x257/0x5d0
Mar 07 05:24:56 nova-1 kernel: schedule+0x68/0x110
Mar 07 05:24:56 nova-1 kernel: schedule_preempt_disabled+0x15/0x30
Mar 07 05:24:56 nova-1 kernel: __mutex_lock.constprop.0+0x4f1/0x750
Mar 07 05:24:56 nova-1 kernel: __mutex_lock_slowpath+0x13/0x20
Mar 07 05:24:56 nova-1 kernel: mutex_lock+0x3e/0x50
Mar 07 05:24:56 nova-1 kernel: mlx5_register_device+0x1c/0xb0 [mlx5_core]
Mar 07 05:24:56 nova-1 kernel: mlx5_init_one+0xe4/0x110 [mlx5_core]
Mar 07 05:24:56 nova-1 kernel: probe_one+0xcb/0x120 [mlx5_core]
Mar 07 05:24:56 nova-1 kernel: local_pci_probe+0x4b/0x90
Mar 07 05:24:56 nova-1 kernel: work_for_cpu_fn+0x1a/0x30
Mar 07 05:24:56 nova-1 kernel: process_one_work+0x21f/0x400
Mar 07 05:24:56 nova-1 kernel: worker_thread+0x200/0x3f0
Mar 07 05:24:56 nova-1 kernel: ? rescuer_thread+0x3a0/0x3a0
Mar 07 05:24:56 nova-1 kernel: kthread+0xee/0x120
Mar 07 05:24:56 nova-1 kernel: ? kthread_complete_and_exit+0x20/0x20
Mar 07 05:24:56 nova-1 kernel: ret_from_fork+0x22/0x30
Mar 07 05:24:56 nova-1 kernel: </TASK>
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