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From:   Karol Herbst <kherbst@redhat.com>
Date:   Mon, 20 Feb 2023 12:26:48 +0100
Message-ID: <CACO55tvGQdHPnZEMAGPZN3K1nUCV-ruX_QNwSqQAg_z81ab0MA@mail.gmail.com>
Subject: Re: linux-6.2-rc4+ hangs on poweroff/reboot: Bisected
To:     Chris Clayton <chris2553@googlemail.com>
Cc:     Ben Skeggs <skeggsb@gmail.com>,
        Linux regressions mailing list <regressions@lists.linux.dev>,
        Dave Airlie <airlied@gmail.com>, bskeggs@redhat.com,
        Lyude Paul <lyude@redhat.com>,
        ML nouveau <nouveau@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>,
        ML dri-devel <dri-devel@lists.freedesktop.org>
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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?

> >>
> >>
> >> .> 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
> >>>>>>>
> >>>>>>
> >>>>>
> >>>>
>