KASAN debug kernel fails to boot at early stage when CONFIG_SMP=y is set (kernel 6.5-rc5, PowerMac G4 3,6)

[Christophe Leroy]

Le 03/09/2023 à 23:06, Erhard Furtner a écrit :
> On Fri, 1 Sep 2023 07:43:34 +0000
> Christophe Leroy <christophe.leroy at csgroup.eu> wrote:
> 
>>>> Can you try what happens when you remove the call to kasan_init() at the
>>>> start of setup_arch() in arch/powerpc/kernel/setup-common.c
>>>
>>> Ok, so I left the other patches in place + btext_map() instead of btext_unmap() at the end of MMU_init() + Michaels patch and additionally commented-out kasan_init() as stated above. The outcome is rather interesting! Now I deterministically get this output at boot OF console, regardless wheter it's a cold boot or warm boot:
>>
>> Ah, my bad. You also need to remove the call to kasan_late_init() in
>> mem_init() in arch/powerpc/mm/mem.c
> 
> Not tragic. Meanwhile I commented-out kasan_late_init() and updated to kernel v6.5.1.
> 
> dmesg did not change however, getting the same "BUG: KASAN: stack-out-of-bounds in __kernel_poison_pages+0x6c/0xd0" as last time only on v6.5.1.
> 


Ok, so lets come back to normal situation. Can you add back kasan_init() 
and kasan_late_init(), while keeping the btext changes and Michael's patch.

Then see what result you get with CONFIG_KASAN but without 
CONFIG_KASAN_VMALLOC

It would help narrow the problem area because kasan_init() does several 
things based on CONFIG_KASAN_VMALLOC.

Thanks
Christophe