Hi Santiago,

Thanks for the details about the question of memory usage, given
the failure mode and your own diligent implementation details, I
believe this can reasonably be ruled out.

Santiago Vila, on 2025-07-09:
> Étienne, on 2025-07-09:
> > I also notice that the kernel run is the cloud variant.  Maybe
> > having a look at differences with the plain kernel could reveal
> > some clues?  (assuming that the problem has not disappeared from
> > 6.12.32 to 6.12.33…)
> 
> That would also be a possibility in theory, but I think it's unlikely.

Right, I tried to isolate the configuration options differences,
and they seem to boil down to:

  * very many hardware specific options being disabled, because
    we're sure that the kernel will run on top of a hypervisor
    with somewhat homogenous context;
  * a couple of hypervisor and cloud specific options are
    enabled, or inlined instead of modular, to survive early
    boot sequence in cloud context.

I admit that I don't see any good reason for such changes to
trigger a chain reaction resulting in a hangup.

> In case it matters, the failure rates that I got recently were:
> 
> 10% (5 out of 50) on systems with 1 CPU
> 78% (39 out of 50) on systems with 2 CPUs.
> 
> I suspect of a race condition of some kind, so if you are still
> willing to try different things (as opposed to directly trying
> in my VM after I finish my last test build), I would try
> bulding the package on a self-hosted qemu/kvm machine
> with exactly 2 CPUs. You can probably achieve the same
> effect by using GRUB_CMDLINE_LINUX="nr_cpus=2" (i.e.
> modify /etc/default/grub, run update-grub and reboot).
> 
> (btw: Building scilab in unstable 100 times as we speak, I believe
> that by night I will be able to tell the outcome).

Acknowledged, I run also a couple of builds locally (as long as
battery capacity allows) and see if I can observe something
interesting if I manage to reproduce a hangup.  If I also have a
78% failure rate, I may have a reasonable chance to see
something tonight.

Have a nice day,  :)
-- 
Étienne Mollier <emoll...@emlwks999.eu>
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