linux-6.2-rc4+ hangs on poweroff/reboot: Bisected

Fri Feb 10 19:33:01 UTC 2023

On 10.02.23 20:01, Karol Herbst wrote:
> On Fri, Feb 10, 2023 at 7:35 PM Linux regression tracking (Thorsten
> Leemhuis) <regressions at leemhuis.info> wrote:
>>
>> On 08.02.23 09:48, Chris Clayton wrote:
>>>
>>> I'm assuming  that we are not going to see a fix for this regression before 6.2 is released.
>>
>> Yeah, looks like it. That's unfortunate, but happens. But there is still
>> time to fix it and there is one thing I wonder:
>>
>> Did any of the nouveau developers look at the netconsole captures Chris
>> posted more than a week ago to check if they somehow help to track down
>> the root of this problem?
> 
> I did now and I can't spot anything. I think at this point it would
> make sense to dump the active tasks/threads via sqsrq keys to see if
> any is in a weird state preventing the machine from shutting down.

Many thx for looking into it!

Ciao, Thorsten

>> Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
>> --
>> Everything you wanna know about Linux kernel regression tracking:
>> https://linux-regtracking.leemhuis.info/about/#tldr
>> If I did something stupid, please tell me, as explained on that page.
>>
>>> Consequently, I've
>>> implemented a (very simple) workaround. All that happens is that in the (sysv) init script that starts and stops SDDM,
>>> the nouveau module is removed once SDDM is stopped. With that in place, my system no longer freezes on reboot or poweroff.
>>>
>>> Let me know if I can provide any additional diagnostics although, with the problem seemingly occurring so late in the
>>> shutdown process, I may need help on how to go about capturing.
>>>
>>> Chris
>>>
>>> On 02/02/2023 20:45, Chris Clayton wrote:
>>>>
>>>>
>>>> On 01/02/2023 13:51, Chris Clayton wrote:
>>>>>
>>>>>
>>>>> On 30/01/2023 23:27, Ben Skeggs wrote:
>>>>>> On Tue, 31 Jan 2023 at 09:09, Chris Clayton <chris2553 at googlemail.com> wrote:
>>>>>>>
>>>>>>> Hi again.
>>>>>>>
>>>>>>> On 30/01/2023 20:19, Chris Clayton wrote:
>>>>>>>> Thanks, Ben.
>>>>>>>
>>>>>>> <snip>
>>>>>>>
>>>>>>>>> Hey,
>>>>>>>>>
>>>>>>>>> This is a complete shot-in-the-dark, as I don't see this behaviour on
>>>>>>>>> *any* of my boards.  Could you try the attached patch please?
>>>>>>>>
>>>>>>>> Unfortunately, the patch made no difference.
>>>>>>>>
>>>>>>>> I've been looking at how the graphics on my laptop is set up, and have a bit of a worry about whether the firmware might
>>>>>>>> be playing a part in this problem. In order to offload video decoding to the NVidia TU117 GPU, it seems the scrubber
>>>>>>>> firmware must be available, but as far as I know,that has not been released by NVidia. To get it to work, I followed
>>>>>>>> what ubuntu have done and the scrubber in /lib/firmware/nvidia/tu117/nvdec/ is a symlink to
>>>>>>>> ../../tu116/nvdev/scrubber.bin. That, of course, means that some of the firmware loaded is for a different card is being
>>>>>>>> loaded. I note that processing related to firmware is being changed in the patch. Might my set up be at the root of my
>>>>>>>> problem?
>>>>>>>>
>>>>>>>> I'll have a fiddle an see what I can work out.
>>>>>>>>
>>>>>>>> Chris
>>>>>>>>
>>>>>>>>>
>>>>>>>>> Thanks,
>>>>>>>>> Ben.
>>>>>>>>>
>>>>>>>>>>
>>>>>>>
>>>>>>> Well, my fiddling has got my system rebooting and shutting down successfully again. I found that if I delete the symlink
>>>>>>> to the scrubber firmware, reboot and shutdown work again. There are however, a number of other files in the tu117
>>>>>>> firmware directory tree that that are symlinks to actual files in its tu116 counterpart. So I deleted all of those too.
>>>>>>> Unfortunately, the absence of one or more of those symlinks causes Xorg to fail to start. I've reinstated all the links
>>>>>>> except scrubber and I now have a system that works as it did until I tried to run a kernel that includes the bad commit
>>>>>>> I identified in my bisection. That includes offloading video decoding to the NVidia card, so what ever I read that said
>>>>>>> the scrubber firmware was needed seems to have been wrong. I get a new message that (nouveau 0000:01:00.0: fb: VPR
>>>>>>> locked, but no scrubber binary!), but, hey, we can't have everything.
>>>>>>>
>>>>>>> If you still want to get to the bottom of this, let me know what you need me to provide and I'll do my best. I suspect
>>>>>>> you might want to because there will a n awful lot of Ubuntu-based systems out there with that scrubber.bin symlink in
>>>>>>> place. On the other hand,m it could but quite a while before ubuntu are deploying 6.2 or later kernels.
>>>>>> The symlinks are correct - whole groups of GPUs share the same FW, and
>>>>>> we use symlinks in linux-firmware to represent this.
>>>>>>
>>>>>> I don't really have any ideas how/why this patch causes issues with
>>>>>> shutdown - it's a path that only gets executed during initialisation.
>>>>>> Can you try and capture the kernel log during shutdown ("dmesg -w"
>>>>>> over ssh? netconsole?), and see if there's any relevant messages
>>>>>> providing a hint at what's going on?  Alternatively, you could try
>>>>>> unloading the module (you will have to stop X/wayland/gdm/etc/etc
>>>>>> first) and seeing if that hangs too.
>>>>>>
>>>>>> Ben.
>>>>>
>>>>> Sorry for the delay - I've been learning about netconsole and netcat. However, I had no success with ssh and netconsole
>>>>> produced a log with nothing unusual in it.
>>>>>
>>>>> Simply stopping Xorg and removing the nouveau module succeeds.
>>>>>
>>>>> So, I rebuilt rc6+ after a pull from linus' tree this morning and set the nouveau debug level to 7. I then booted to a
>>>>> console before doing a reboot (with Ctl+Alt+Del). As expected the machine locked up just before it would ordinarily
>>>>> restart. The last few lines on the console might be helpful:
>>>>>
>>>>> ...
>>>>> nouveau 0000:01:00:0  fifo: preinit running...
>>>>> nouveau 0000:01:00:0  fifo: preinit completed in 4us
>>>>> nouveau 0000:01:00:0  gr: preinit running...
>>>>> nouveau 0000:01:00:0  gr: preinit completed in 0us
>>>>> nouveau 0000:01:00:0  nvdec0: preinit running...
>>>>> nouveau 0000:01:00:0  nvdec0: preinit completed in 0us
>>>>> nouveau 0000:01:00:0  nvdec0: preinit running...
>>>>> nouveau 0000:01:00:0  nvdec0: preinit completed in 0us
>>>>> nouveau 0000:01:00:0  sec2: preinit running...
>>>>> nouveau 0000:01:00:0  sec2: preinit completed in 0us
>>>>> nouveau 0000:01:00:0  fb:.VPR locked, running scrubber binary
>>>>>
>>>>> These messages appear after the "sd 4:0:0:0 [sda] Stopping disk" I reported in my initial email.
>>>>>
>>>>> After the "running scrubber" line appears the machine is locked and I have to hold down the power button to recover. I
>>>>> get the same outcome from running "halt -dip", "poweroff -di" and "shutdown -h -P now". I guess it's no surprise that
>>>>> all three result in the same outcome because invocations halt, poweroff and reboot (without the -f argument)from a
>>>>> runlevel other than 0 resukt in shutdown being run. switching to runlevel 0 with "telenit 0" results in the same
>>>>> messages from nouveau followed by the lockup.
>>>>>
>>>>> Let me know if you need any additional diagnostics.
>>>>>
>>>>> Chris
>>>>>
>>>>
>>>> I've done some more investigation and found that I hadn't done sufficient amemdment the scripts run at shutdown to
>>>> prevent the network being shutdown. I've now got netconsole captures for 6.2.0-rc6+
>>>> (9f266ccaa2f5228bfe67ad58a94ca4e0109b954a) and, for comparison, 6.1.9. These two logs are attached.
>>>>
>>>> Chris
>>>>
>>>>>>
>>>>>>>
>>>>>>> Thanks,
>>>>>>>
>>>>>>> Chris
>>>>>>>
>>>>>>> <snip>
>>>
>>>
>>
> 
> 
> 