Debian SID kernel doesn't boot on PowerBook 3400c

[Finn Thain]

On Tue, 3 Aug 2021, Christophe Leroy wrote:

> 
> Looks like the memory errors are linked to KUAP (Kernel Userspace Access 
> Protection). Based on the places the problems happen, I don't think 
> there are any invalid access, so there must be something wrong in the 
> KUAP logic, probably linked to some interrupts happenning in kernel mode 
> while the KUAP window is opened. And because is not selected by default 
> on book3s/32 until 5.14, probably nobody ever tested it in a real 
> environment before you.
> 
> I think the issue may be linked to commit 
> https://github.com/linuxppc/linux/commit/c16728835 which happened 
> between 5.12 and 5.13.

The messages, "Kernel attempted to write user page (c6207c) - exploit 
attempt? (uid: 0)", appear in the console logs generated by v5.13. Those 
logs come from the Powerbook G3 discussion in the other thread. Could that 
be the same bug?