On Wed, 2017-02-15 at 09:08 +0100, Miloslav Hula wrote:
[...]
> When I boot the system up, there is a constant load 1.0. I found one
> process systemd-udevd in uninterruptible sleep.
> Digging in proc/PID/fd I found, this proces usees fd 7 for
> intel_rapl_perf.ko
> 
> * What exactly did you do (or not do) that was effective (or
> ineffective)?
> I rmmod intel_rapl_perf, the systemd-udevd process disappeared. I
> tried to load intel_rapl_perf manually.
> 
> * What was the outcome of this action?
> Now, the modprobe is in uninterruptible sleep
[...]

Here's a traceback for that:

> [ 1090.784109] INFO: task systemd-udevd:1182 blocked for more than 120 seconds.
> [ 1090.784167]       Not tainted 4.9.0-0.bpo.1-amd64 #1
> [ 1090.784202] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
> [ 1090.784254] systemd-udevd   D    0  1182   1098 0x00000004
> [ 1090.784260]  ffffa079b6c9d000 0000000000000000 ffffa089b8ffa0c0 ffffa079b688c140
> [ 1090.784265]  ffffa089bf2987c0 ffffc1d3ce12bb30 ffffffff929f536d ffffa089bf3d8828
> [ 1090.784268]  ffffc1d3ce12bb60 00000000924b0afe ffffa089bf2987c0 ffffa079b688c140
> [ 1090.784272] Call Trace:
> [ 1090.784284]  [<ffffffff929f536d>] ? __schedule+0x23d/0x6d0
> [ 1090.784308]  [<ffffffffc083e6b0>] ? uncore_cpu_prepare+0x100/0x100 [intel_uncore]
> [ 1090.784310]  [<ffffffff929f5832>] ? schedule+0x32/0x80
> [ 1090.784316]  [<ffffffff929f8d3c>] ? schedule_timeout+0x21c/0x3c0
> [ 1090.784327]  [<ffffffff924b1374>] ? enqueue_task_fair+0x74/0x950
> [ 1090.784329]  [<ffffffff929f5375>] ? __schedule+0x245/0x6d0
> [ 1090.784336]  [<ffffffff9242ed05>] ? sched_clock+0x5/0x10
> [ 1090.784344]  [<ffffffffc083e6b0>] ? uncore_cpu_prepare+0x100/0x100 [intel_uncore]
> [ 1090.784347]  [<ffffffff929f624a>] ? wait_for_completion+0xfa/0x130
> [ 1090.784353]  [<ffffffff924a2b60>] ? wake_up_q+0x60/0x60
> [ 1090.784358]  [<ffffffff924791b6>] ? cpuhp_issue_call+0x96/0xc0
> [ 1090.784361]  [<ffffffff9247946a>] ? __cpuhp_setup_state+0xca/0x200
> [ 1090.784369]  [<ffffffffc069d34d>] ? intel_uncore_init+0x1f7/0xeaa [intel_uncore]
> [ 1090.784376]  [<ffffffffc069d156>] ? uncore_type_init+0x156/0x156 [intel_uncore]
> [ 1090.784383]  [<ffffffff9240218c>] ? do_one_initcall+0x4c/0x180
> [ 1090.784393]  [<ffffffff9257cbaf>] ? do_init_module+0x5a/0x1f1
> [ 1090.784400]  [<ffffffff92502729>] ? load_module+0x23c9/0x28f0
> [ 1090.784403]  [<ffffffff924fef90>] ? __symbol_put+0x60/0x60
> [ 1090.784411]  [<ffffffff92603964>] ? vfs_read+0x114/0x130
> [ 1090.784418]  [<ffffffff926a4351>] ? security_capable+0x41/0x60
> [ 1090.784421]  [<ffffffff92502e3e>] ? SYSC_finit_module+0x8e/0xe0
> [ 1090.784425]  [<ffffffff929fa1bb>] ? system_call_fast_compare_end+0xc/0x9b
[...]

The CPU is a Broadwell (I don't have more information than that);
here's the model information from DMI:

> ** Model information
> sys_vendor: Supermicro
> product_name: X10DRi
> product_version: 123456789
> chassis_vendor: Default string
> chassis_version: Default string
> bios_vendor: American Megatrends Inc.
> bios_version: 2.1
> board_vendor: Supermicro
> board_name: X10DRi
> board_version: 1.02B
[...]

The full bug report is at <https://bugs.debian.org/855183>, with a
little more system information.

Ben.

-- 
Ben Hutchings
Any sufficiently advanced bug is indistinguishable from a feature.