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

[Karol Herbst <kherbst@redhat.com>]

On Fri, Mar 10, 2023 at 10:26 AM Chris Clayton <chris2553@googlemail.com> wrote:
>
> Hi.
>
> Is it likely that this fix will be sumbmitted to mainline during the ongoing 6.3 development cycle?
>

yes, it's already pushed to drm-misc-fixed, which then will go into
the current devel cycle. I just don't know when it's the next time it
will be pushed upwards, but it should get there eventually. And
because it also contains a Fixes tag it will be backported to older
branches as well.

> Chris
>
> On 20/02/2023 22:16, Ben Skeggs wrote:
> > On Mon, 20 Feb 2023 at 21:27, Karol Herbst <kherbst@redhat.com> wrote:
> >>
> >> On Mon, Feb 20, 2023 at 11:51 AM Chris Clayton <chris2553@googlemail.com> wrote:
> >>>
> >>>
> >>>
> >>> On 20/02/2023 05:35, Ben Skeggs wrote:
> >>>> On Sun, 19 Feb 2023 at 04:55, Chris Clayton <chris2553@googlemail.com> wrote:
> >>>>>
> >>>>>
> >>>>>
> >>>>> On 18/02/2023 15:19, Chris Clayton wrote:
> >>>>>>
> >>>>>>
> >>>>>> On 18/02/2023 12:25, Karol Herbst wrote:
> >>>>>>> On Sat, Feb 18, 2023 at 1:22 PM Chris Clayton <chris2553@googlemail.com> wrote:
> >>>>>>>>
> >>>>>>>>
> >>>>>>>>
> >>>>>>>> On 15/02/2023 11:09, Karol Herbst wrote:
> >>>>>>>>> On Wed, Feb 15, 2023 at 11:36 AM Linux regression tracking #update
> >>>>>>>>> (Thorsten Leemhuis) <regressions@leemhuis.info> wrote:
> >>>>>>>>>>
> >>>>>>>>>> On 13.02.23 10:14, Chris Clayton wrote:
> >>>>>>>>>>> On 13/02/2023 02:57, Dave Airlie wrote:
> >>>>>>>>>>>> On Sun, 12 Feb 2023 at 00:43, Chris Clayton <chris2553@googlemail.com> wrote:
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> On 10/02/2023 19:33, Linux regression tracking (Thorsten Leemhuis) wrote:
> >>>>>>>>>>>>>> On 10.02.23 20:01, Karol Herbst wrote:
> >>>>>>>>>>>>>>> On Fri, Feb 10, 2023 at 7:35 PM Linux regression tracking (Thorsten
> >>>>>>>>>>>>>>> Leemhuis) <regressions@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!
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> Yes, thanks Karol.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> Attached is the output from dmesg when this block of code:
> >>>>>>>>>>>>>
> >>>>>>>>>>>>>         /bin/mount /dev/sda7 /mnt/sda7
> >>>>>>>>>>>>>         /bin/mountpoint /proc || /bin/mount /proc
> >>>>>>>>>>>>>         /bin/dmesg -w > /mnt/sda7/sysrq.dmesg.log &
> >>>>>>>>>>>>>         /bin/echo t > /proc/sysrq-trigger
> >>>>>>>>>>>>>         /bin/sleep 1
> >>>>>>>>>>>>>         /bin/sync
> >>>>>>>>>>>>>         /bin/sleep 1
> >>>>>>>>>>>>>         kill $(pidof dmesg)
> >>>>>>>>>>>>>         /bin/umount /mnt/sda7
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> is executed immediately before /sbin/reboot is called as the final step of rebooting my system.
> >>>>>>>>>>>>>
> >>>>>>>>>>>>> I hope this is what you were looking for, but if not, please let me know what you need
> >>>>>>>>>>>
> >>>>>>>>>>> Thanks Dave. [...]
> >>>>>>>>>> FWIW, in case anyone strands here in the archives: the msg was
> >>>>>>>>>> truncated. The full post can be found in a new thread:
> >>>>>>>>>>
> >>>>>>>>>> https://lore.kernel.org/lkml/e0b80506-b3cf-315b-4327-1b988d86031e@googlemail.com/
> >>>>>>>>>>
> >>>>>>>>>> Sadly it seems the info "With runpm=0, both reboot and poweroff work on
> >>>>>>>>>> my laptop." didn't bring us much further to a solution. :-/ I don't
> >>>>>>>>>> really like it, but for regression tracking I'm now putting this on the
> >>>>>>>>>> back-burner, as a fix is not in sight.
> >>>>>>>>>>
> >>>>>>>>>> #regzbot monitor:
> >>>>>>>>>> https://lore.kernel.org/lkml/e0b80506-b3cf-315b-4327-1b988d86031e@googlemail.com/
> >>>>>>>>>> #regzbot backburner: hard to debug and apparently rare
> >>>>>>>>>> #regzbot ignore-activity
> >>>>>>>>>>
> >>>>>>>>>
> >>>>>>>>> yeah.. this bug looks a little annoying. Sadly the only Turing based
> >>>>>>>>> laptop I got doesn't work on Nouveau because of firmware related
> >>>>>>>>> issues and we probably need to get updated ones from Nvidia here :(
> >>>>>>>>>
> >>>>>>>>> But it's a bit weird that the kernel doesn't shutdown, because I don't
> >>>>>>>>> see anything in the logs which would prevent that from happening.
> >>>>>>>>> Unless it's waiting on one of the tasks to complete, but none of them
> >>>>>>>>> looked in any way nouveau related.
> >>>>>>>>>
> >>>>>>>>> If somebody else has any fancy kernel debugging tips here to figure
> >>>>>>>>> out why it hangs, that would be very helpful...
> >>>>>>>>>
> >>>>>>>>
> >>>>>>>> I think I've figured this out. It's to do with how my system is configured. I do have an initrd, but the only thing on
> >>>>>>>> it is the cpu microcode which, it is recommended, should be loaded early. The absence of the NVidia firmare from an
> >>>>>>>> initrd doesn't matter because the drivers for the hardware that need to load firmware are all built as modules, So, by
> >>>>>>>> the time the devices are configured via udev, the root partition is mounted and the drivers can get at the firmware.
> >>>>>>>>
> >>>>>>>> I've found, by turning on nouveau debug and taking a video of the screen as the system shuts down, that nouveau seems to
> >>>>>>>> be trying to run the scrubber very very late in the shutdown process. The problem is that by this time, I think the root
> >>>>>>>> partition, and thus the scrubber binary, have become inaccessible.
> >>>>>>>>
> >>>>>>>> I seem to have two choices - either make the firmware accessible on an initrd or unload the module in a shutdown script
> >>>>>>>> before the scrubber binary becomes inaccessible. The latter of these is the workaround I have implemented whilst the
> >>>>>>>> problem I reported has been under investigation. For simplicity, I think I'll promote my workaround to being the
> >>>>>>>> permanent solution.
> >>>>>>>>
> >>>>>>>> So, apologies (and thanks) to everyone whose time I have taken up with this non-bug.
> >>>>>>>>
> >>>>>>>
> >>>>>>> Well.. nouveau shouldn't prevent the system from shutting down if the
> >>>>>>> firmware file isn't available. Or at least it should print a
> >>>>>>> warning/error. Mind messing with the code a little to see if skipping
> >>>>>>> it kind of works? I probably can also come up with a patch by next
> >>>>>>> week.
> >>>>>>>
> >>>>>> Well, I'd love to but a quick glance at the code caused me to bump into this obscenity:
> >>>>>>
> >>>>>> int
> >>>>>> gm200_flcn_reset_wait_mem_scrubbing(struct nvkm_falcon *falcon)
> >>>>>> {
> >>>>>>         nvkm_falcon_mask(falcon, 0x040, 0x00000000, 0x00000000);
> >>>>>>
> >>>>>>         if (nvkm_msec(falcon->owner->device, 10,
> >>>>>>                 if (!(nvkm_falcon_rd32(falcon, 0x10c) & 0x00000006))
> >>>>>>                         break;
> >>>>>>         ) < 0)
> >>>>>>                 return -ETIMEDOUT;
> >>>>>>
> >>>>>>         return 0;
> >>>>>> }
> >>>>>>
> >>>>>> nvkm_msec is #defined to nvkm_usec which in turn is #defined to nvkm_nsec where the loop that the break is related to
> >>>>>> appears
> >>>>>
> >>>>> I think someone who knows the code needs to look at this. What I can confirm is that after a freeze, I waited for 90
> >>>>> seconds for a timeout to occur, but it didn't.
> >>>> Hey,
> >>>>
> >>>> Are you able to try the attached patch for me please?
> >>>>
> >>>> Thanks,
> >>>> Ben.
> >>>>
> >>>
> >>> Thanks Ben.
> >>>
> >>> Yes, this patch fixes the lockup on reboot and poweroff that I've been seeing on my laptop. As you would expect,
> >>> offloaded rendering is still working and the discrete GPU is being powered on and off as required.
> >>>
> >>> Thanks.
> >>>
> >>> Reported-by: Chris Clayton <chris2553@googlemail.com>
> >>> Tested-by: Chris Clayton <chris2553@googlemail.com>
> >>>
> >>
> >> Ben, did you manage to get push rights to drm-misc by now or should I
> >> just pick the patch and push it through -fixes?
> > Feel free to pick it up!
> >
> > Thank you,
> > Ben.
> >
> >>
> >>>>>
> >>>>>
> >>>>> .> Chris
> >>>>>>>>
> >>>>>>>>>> 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
> >>>>>>>>>> That page also explains what to do if mails like this annoy you.
> >>>>>>>>>>
> >>>>>>>>>> #regzbot ignore-activity
> >>>>>>>>>>
> >>>>>>>>>
> >>>>>>>>
> >>>>>>>
> >>>
> >>
>