Re: Kernel versions 6.x don't boot on Amiga 4000

[Michael Schmitz <schmitzmic@gmail.com>]

Hi Geert,

Am 27.02.2023 um 01:52 schrieb Geert Uytterhoeven:
> On Sun, Feb 26, 2023 at 12:02 PM Geert Uytterhoeven
> <geert@linux-m68k.org> wrote:
>> On Tue, Feb 21, 2023 at 4:53 PM John Paul Adrian Glaubitz
>> <glaubitz@physik.fu-berlin.de> wrote:
>>> On Tue, 2023-02-21 at 15:55 +0100, Geert Uytterhoeven wrote:
>>>> Looks surprisingly similar to the issue reported by Stan.
>>>> Do the mitigations given in
>>>> https://lore.kernel.org/all/CAMuHMdUtkr2zvZiJfLXvs9d_inJbktSNqQQfO1oxnJHZeoYcHg@mail.gmail.com
>>>> help?
>>>
>>> The kernel actually crashes with a backtrace:
>>>
>>> ABCDGHIJK
>>> [    0.000000] Linux version 6.0.0-6-m68k (debian-kernel@lists.debian.org) (gcc-12 (Debian 12.2.0-9) 12.2.0, GNU ld (GNU Binutils for
>>> Debian) 2.39) #1 Debian 6.0.12-1 (2022-12-09)
>>> [    0.000000] Enabling workaround for errata I14
>>> [    0.000000] printk: bootconsole [debug0] enabled
>>> [    0.000000] Amiga hardware found: [A4000] VIDEO BLITTER AUDIO FLOPPY A4000_IDE KEYBOARD MOUSE SERIAL PARALLEL A3000_CLK CHIP_RAM PAULA
>>> LISA ALICE_PAL ZORRO3
>>> [    0.000000] initrd: 0ef0602c - 0f800000
>>> [    0.000000] Zone ranges:
>>> [    0.000000]   DMA      [mem 0x0000000008000000-0x000000f7ffffffff]
>>> [    0.000000]   Normal   empty
>>> [    0.000000] Movable zone start for each node
>>> [    0.000000] Early memory node ranges
>>> [    0.000000]   node   0: [mem 0x0000000008000000-0x000000000f7fffff]
>>> [    0.000000] Initmem setup node 0 [mem 0x0000000008000000-0x000000000f7fffff]
>>> [    0.000000] Unable to handle kernel access at virtual address (ptrval)
>>
>> I see the same issue on my A4000, bisecting...
>
> Bisected to commit 376e3fdecb0dcae2 ("m68k: Enable memtest
> functionality") in v5.17-rc1.  Reverting that on top of latest fixes the

What about instead changing the piece of code that you identified as 
problematic in Kars' case to claim/map the last few bits as well 
(memblock_cap_size() to be precise)?

I wonder whether Finn's memtest patch merely exposed another MM bug that 
we don't hit as easily (not without putting memory under a lot of pressure)?

Cheers,

	Michael


> issue.
>
> Gr{oetje,eeting}s,
>
>                         Geert
>