Re: Regression in 028abd92 for Sun UltraSPARC T1

[Frank Scheiner <frank.scheiner@web.de>]

On 23.03.21 17:57, Christoph Hellwig wrote:
> On Tue, Mar 23, 2021 at 05:50:59PM +0100, Jan Engelhardt wrote:
>> Some participants in the discussion over at the debian-sparc list mentioned
>> "NFS" and "Invalid argument", which is something I know just too well from
>> iptables. NFS is a filesystem that uses an extra data blob (5th argument to the
>> mount syscall). Such blobs have historically not always been designed to bear
>> the same layout between ILP32 and LP64 modes, and nfs's structs fell prey to
>> this as well.
>>
>> My hypothesis now is that fs/nfs/fs_context.c line 1160:
>>
>> 	if (in_compat_syscall())
>> 		nfs4_compat_mount_data_conv(data);
>>
>> and ones similar to it (I didn't look too close where nfs3 gets to do its
>> conversion), no longer trigger as a result of compat_sys_mount being
>> wiped from the syscall table:
>
> No, if in_compat_syscall() syscall doesn't trigger properly the kernel
> would not get this far.
>
> That being said, the NFS compat code was moved out of the compat mount
> handler and into nfs and refactored in the commit just before this one.
>
> Frank, can you double check that commit
> 67e306c6906137020267eb9bbdbc127034da3627 really still works, and
> only 028abd9222df0cf5855dab5014a5ebaf06f90565 broke your setup?

Indeed, I also expected 67e306c6906137020267eb9bbdbc127034da3627 to fail
because of its commit message, but from my log it did work correctly.

As the T1000 is at home and I don't have another T1 based system in my
storage location where I am now, I'll double check that in the evening
and report back.

Strangely for a V245 (with UltraSPARC IIIi) both commits seem to work
according to my testing, but 5.10.x (from Debian) doesn't work and
5.9.15 (also from Debian) does work - tested now both for boot from
network and boot from disk.

Possibly unrelated to the problem with the T1000, the V245 emits the
following for boot from disk with 5.10.x:

```
[...]
Loading Linux 5.10.0-5-sparc64-smp ...
Loading initial ramdisk ...

[    2.602821] rtc_cmos rtc_cmos: IRQ index 0 not found
/dev/sda2: clean, 33516/8454144 files, 1105784/33798750 blocks
[   13.542728] autofs4:pid:1:autofs_fill_super: called with bogus options
[   13.628931] systemd[1]: proc-sys-fs-binfmt_misc.automount: Failed to
initialize automounter: Invalid argument
[   13.759917] systemd[1]: Failed to set up automount Arbitrary
Executable File Formats File System Automount Point.
[FAILED] Failed to set up automount  File System Automount Point.
[   14.456396] Unable to handle kernel paging request in mna handler
[   14.456400]  at virtual address da65f2fed110e482
[   14.597474] current->{active_,}mm->context = 00000000000000ce
[   14.597478] current->{active_,}mm->pgd = fff0000006d5c000
[   14.752380] Unable to handle kernel paging request in mna handler
[   14.752383]  at virtual address da65f2fed110e482
[   14.893509] current->{active_,}mm->context = 0000000000000094
[   14.969141] current->{active_,}mm->pgd = fff00011010e0000
[   15.040554] Kernel panic - not syncing: Attempted to kill init!
exitcode=0x00000009
[   15.141430] Press Stop-A (L1-A) from sun keyboard or send break
[   15.141430] twice on console to return to the boot prom
[   15.141459] kernel BUG at kernel/cpu.c:960
```

Cheers,
Frank