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

From: Erhard Furtner <[email-masked]>
Date: Thu, 17 Aug 2023 20:32:02 +0200

On Wed, 16 Aug 2023 15:56:26 +0000
Christophe Leroy <[email-masked]> wrote:

> Not sure this is the reason of the crash. Just that it disables bootx 
> console here and doesn't re-enable any console before the crash.
> 
> Could you move the call to btext_unmap() after the call to 
> memblock_set_current_limit(lowmem_end_addr); at the end of function 
> MMU_init()
> 
> And redo the test, still with my patch applied for the additional pr_infos.

I moved btext_unmap() as you suggested and the order of functions displayed changed accordingly. Now the freeze happens later but still after the 1st call to btext_unmap():

[    0.000000] printk: bootconsole [udbg0] enabled
[    0.000000] Total memory = 2048MB; using 4096kB for hash table
[    0.000000] mapin_ram:125
[    0.000000] mmu_mapin_ram:169 0 30000000 1400000 2000000
[    0.000000] __mmu_mapin_ram:146 0 1400000
[    0.000000] __mmu_mapin_ram:155 1400000
[    0.000000] __mmu_mapin_ram:146 1400000 30000000
[    0.000000] __mmu_mapin_ram:155 20000000
[    0.000000] __mapin_ram_chunk:107 20000000 30000000
[    0.000000] __mapin_ram_chunk:117
[    0.000000] mapin_ram:134
[    0.000000] kasan_mmu_init:129
[    0.000000] kasan_mmu_init:132 0
[    0.000000] kasan_mmu_init:137
[    0.000000] setup_kuap:23
[    0.000000] setup_kuap:25
[    0.000000] setup_kuap:30
[    0.000000] setup_kuap:35
[    0.000000] Activating Kernel Userspace Access Protection
[    0.000000] setup_kuap:40
[    0.000000] Activating Kernel Userspace Execution Prevention
[    0.000000] btext_unmap:129

Regards,
Erhard