Date:   Mon, 20 Feb 2023 15:35:06 +1000
From:   Ben Skeggs <skeggsb@...il.com>
To:     Chris Clayton <chris2553@...glemail.com>
Cc:     Karol Herbst <kherbst@...hat.com>,
        Linux regressions mailing list <regressions@...ts.linux.dev>,
        Dave Airlie <airlied@...il.com>, bskeggs@...hat.com,
        Lyude Paul <lyude@...hat.com>,
        ML nouveau <nouveau@...ts.freedesktop.org>,
        LKML <linux-kernel@...r.kernel.org>,
        ML dri-devel <dri-devel@...ts.freedesktop.org>
Subject: Re: linux-6.2-rc4+ hangs on poweroff/reboot: Bisected

On Sun, 19 Feb 2023 at 04:55, Chris Clayton <chris2553@...glemail.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@...glemail.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@...mhuis.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@...glemail.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@...mhuis.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.

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

View attachment "0001-drm-nouveau-fb-gp102-cache-scrubber-binary-on-first-.patch" of type "text/x-patch" (9335 bytes)

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