Kernel 6.4-rc1 ARM boot fails

Kernel 6.4-rc1 ARM boot fails

[Colin Foster]

Hi Ard,

I just wanted to give a heads up. I tested 6.4-rc1 on a Beaglebone Black
and kept getting boot hangs. A bisect led me to commit c76c6c4ecbec ("ARM:
9294/2: vfp: Fix broken softirq handling with instrumentation enabled").

The dying message is "Run /sbin/init as init process"

I'm not sure if this has already been reported. I was able to revert this
patch and confirm things work again.


My current kernel version with the revert is below. I can share my kconfig
if that's needed.

```
# uname -a
Linux buildroot 6.4.0-rc1-00022-g6ceb2f82fe40 #1313 SMP PREEMPT Tue May  9 23:02:58 PDT 2023 armv7l GNU/Linux
```


Thanks, and let me know if you need any more information from me.


Colin Foster

Re: Kernel 6.4-rc1 ARM boot fails

[Ard Biesheuvel]

On Wed, 10 May 2023 at 08:30, Colin Foster
<colin.foster@in-advantage.com> wrote:
>
> Hi Ard,
>
> I just wanted to give a heads up. I tested 6.4-rc1 on a Beaglebone Black
> and kept getting boot hangs. A bisect led me to commit c76c6c4ecbec ("ARM:
> 9294/2: vfp: Fix broken softirq handling with instrumentation enabled").
>
> The dying message is "Run /sbin/init as init process"
>
> I'm not sure if this has already been reported. I was able to revert this
> patch and confirm things work again.
>
>
> My current kernel version with the revert is below. I can share my kconfig
> if that's needed.
>
> ```
> # uname -a
> Linux buildroot 6.4.0-rc1-00022-g6ceb2f82fe40 #1313 SMP PREEMPT Tue May  9 23:02:58 PDT 2023 armv7l GNU/Linux
> ```
>
>
> Thanks, and let me know if you need any more information from me.
>


Thanks for the report.

This should fix it:

https://www.armlinux.org.uk/developer/patches/viewpatch.php?id=9297/1

Re: Kernel 6.4-rc1 ARM boot fails

[Colin Foster]

On Wed, May 10, 2023 at 08:33:00AM +0200, Ard Biesheuvel wrote:
> On Wed, 10 May 2023 at 08:30, Colin Foster
> 
> Thanks for the report.
> 
> This should fix it:
> 
> https://www.armlinux.org.uk/developer/patches/viewpatch.php?id=9297/1

Looks like it. I'll apply then wait for the next RC. Thanks for this,
and the super quick response!

Re: Kernel 6.4-rc1 ARM boot fails

[Linux regression tracking #adding (Thorsten Leemhuis)]

[CCing the regression list, as it should be in the loop for regressions:
https://docs.kernel.org/admin-guide/reporting-regressions.html]

[TLDR: I'm adding this report to the list of tracked Linux kernel
regressions; the text you find below is based on a few templates
paragraphs you might have encountered already in similar form.
See link in footer if these mails annoy you.]

On 10.05.23 08:30, Colin Foster wrote:
> 
> I just wanted to give a heads up. I tested 6.4-rc1 on a Beaglebone Black
> and kept getting boot hangs. A bisect led me to commit c76c6c4ecbec ("ARM:
> 9294/2: vfp: Fix broken softirq handling with instrumentation enabled").
>
> The dying message is "Run /sbin/init as init process"
> 
> I'm not sure if this has already been reported. I was able to revert this
> patch and confirm things work again.
> [...]

Thanks for the report. I know a fix is incoming, but to be sure the
issue doesn't fall through the cracks unnoticed, I'm adding it to
regzbot, the Linux kernel regression tracking bot:

#regzbot ^introduced c76c6c4ecbec
#regzbot title arm32: tons of different boot time errors
#regzbot ignore-activity
#regzbot monitor:
https://lore.kernel.org/all/000000000000d3001a05faf979c8@google.com/
#regzbot fix ARM: 9297/1: vfp: avoid unbalanced stack on 'success'
return path
#regzbot monitor:
https://lore.kernel.org/all/20230506161325.223362-1-ardb@kernel.org/


This isn't a regression? This issue or a fix for it are already
discussed somewhere else? It was fixed already? You want to clarify when
the regression started to happen? Or point out I got the title or
something else totally wrong? Then just reply and tell me -- ideally
while also telling regzbot about it, as explained by the page listed in
the footer of this mail.

Developers: When fixing the issue, remember to add 'Link:' tags pointing
to the report (the parent of this mail). See page linked in footer for
details.

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.

Re: Kernel 6.4-rc1 ARM boot fails

[Linus Walleij]

On Sun, May 14, 2023 at 3:15 PM Linux regression tracking #adding
(Thorsten Leemhuis) <regressions@leemhuis.info> wrote:

> This isn't a regression? This issue or a fix for it are already
> discussed somewhere else? It was fixed already?

It was fixed already.

> You want to clarify when
> the regression started to happen? Or point out I got the title or
> something else totally wrong? Then just reply and tell me -- ideally
> while also telling regzbot about it, as explained by the page listed in
> the footer of this mail.
>
> Developers: When fixing the issue, remember to add 'Link:' tags pointing
> to the report (the parent of this mail). See page linked in footer for
> details.

Syzbot also ran into this regression:
https://lore.kernel.org/all/000000000000da2a8505fb71d81b@google.com/

Anything using FP instructions in userspace init will crash like that,
I happened to use softfloat in all my userspaces and didn't face it.

Yours,
Linus Walleij