Re: [PATCH v2 08/13] sparc64: vdso: Switch to the generic vDSO library

[Andreas Larsson <andreas@gaisler.com>]

On 2025-08-26 07:56, Thomas Weißschuh wrote:
> Hi Andreas,
> 
> thaks for testing!
> 
> On Mon, Aug 25, 2025 at 05:55:20PM +0200, Andreas Larsson wrote:
>> On 2025-08-15 12:41, Thomas Weißschuh wrote:
>>> The generic vDSO provides a lot common functionality shared between
>>> different architectures. SPARC is the last architecture not using it,
>>> preventing some necessary code cleanup.
>>>
>>> Make use of the generic infrastructure.
>>>
>>> Signed-off-by: Thomas Weißschuh <thomas.weissschuh@linutronix.de>
>>> ---
>>>  arch/sparc/Kconfig                         |   4 +-
>>>  arch/sparc/include/asm/clocksource.h       |   9 --
>>>  arch/sparc/include/asm/vdso/clocksource.h  |  10 ++
>>>  arch/sparc/include/asm/vdso/gettimeofday.h |  58 ++++++++--
>>>  arch/sparc/include/asm/vdso/vsyscall.h     |  10 ++
>>>  arch/sparc/include/asm/vvar.h              |  75 -------------
>>>  arch/sparc/kernel/Makefile                 |   1 -
>>>  arch/sparc/kernel/time_64.c                |   6 +-
>>>  arch/sparc/kernel/vdso.c                   |  69 ------------
>>>  arch/sparc/vdso/Makefile                   |   6 +-
>>>  arch/sparc/vdso/vclock_gettime.c           | 169 ++++-------------------------
>>>  arch/sparc/vdso/vdso-layout.lds.S          |   7 +-
>>>  arch/sparc/vdso/vma.c                      |  70 +++---------
>>>  13 files changed, 119 insertions(+), 375 deletions(-)
>>
>> With the first seven patches (applied on v6.17-rc1) I don't run into any
>> problems, but from this patch (and onwards) things do not work properly.
>> With patches 1-8 applied, Debian running on a sun4v (in a Solaris LDOM)
>> stops being able to mount the root filesystem with the patches applied
>> up to and including this patch.
> 
> Could you give me the kernel log of the failures? 

Not sure if fuller logs would help, but with the 8 first patches applied
I get this behaviour when the kernel is trying to run /init:

----------------%<----------------
[    1.850062] Run /init as init process
Loading, please wait...
Starting systemd-udevd version 257.7-1
Begin: Loading essential drivers ... done.
Begin: Running /scripts/init-premount ... done.
Begin: Mounting root file system ... Begin: Running /scripts/local-top ... done.
Begin: Running /scripts/local-premount ... Begin: Waiting for suspend/resume device ... Begin: Running /scripts/local-block ... done.
Begin: Running /scripts/local-block ... done.
Begin: Running /scripts/local-block ... done.
[    5.386073] sched: DL replenish lagged too much
Begin: Running /scripts/local-block ... done.
--%<-- <25 identical lines> --%<--
Begin: Running /scripts/local-block ... done.
done.
Gave up waiting for suspend/resume device
done.
Begin: Waiting for root file system ... Begin: Running /scripts/local-block ... done.
done.
Gave up waiting for root file system device.  Common problems:
 - Boot args (cat /proc/cmdline)
   - Check rootdelay= (did the system wait long enough?)
 - Missing modules (cat /proc/modules; ls /dev)
ALERT!  UUID=2351ccc2-3dbd-4de6-9221-255a8e1fb132 does not exist.  Dropping to a shell!
----------------%<----------------

and with all of them applied I got: 

----------------%<----------------
[    1.849344] Run /init as init process
[    1.851309] Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
[    1.851339] CPU: 4 UID: 0 PID: 1 Comm: init Not tainted 6.17.0-rc1+ #3 VOLUNTARY
[    1.851363] Call Trace:
[    1.851374] [<0000000000436524>] dump_stack+0x8/0x18
[    1.851400] [<00000000004291f4>] vpanic+0xdc/0x320
[    1.851420] [<000000000042945c>] panic+0x24/0x30
[    1.851437] [<00000000004844a4>] do_exit+0xac4/0xae0
[    1.851458] [<0000000000484684>] do_group_exit+0x24/0xa0
[    1.851476] [<0000000000494c60>] get_signal+0x900/0x940
[    1.851495] [<000000000043ecb8>] do_notify_resume+0xf8/0x600
[    1.851514] [<0000000000404b48>] __handle_signal+0xc/0x30
[    1.852291] Press Stop-A (L1-A) from sun keyboard or send break
[    1.852291] twice on console to return to the boot prom
[    1.852310] ---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]---
----------------%<----------------

but given that I don't have the kernel anymore I'm starting to
question myself if that run was really with the same base
commit. I'll do a rebuild and see.

> Is there any chance to get access to the machine? 

Such access is not mine to give I'm afraid.

> Can you reproduce this issue on sun4u? sun4v in QEMU is
> "work in progress" and instantly crashes for me. 

My current vDSO testing kernels aiming for this Debian setup are not
playing well with QEMU right now. I have to look into this.

> Can you provide me your Debian image?

What do you mean with image here? Disk image? Kernel image? This is a 25
GiB installation.

> 
>> As an aside, with all patches applied, it panics when the kernel
>> attempts to kill init.
> 
> It is suprising that the error changes between patches.
> The later patches don't change any lowlevel stuff, so if rootfs mounting
> was broken earlier I don't see how it could go on to start init later.
> Are these results repeatable?

The one with 8 patches is reliably repeatable. The one with all patches
seems to have been purged for space reasons, but I saw the same problem
multiple/all times as far as I remember. In any case, at least 7 patches
works reliably every time when 8 patches fails in the same way every
time.


Cheers,
Andreas