Re: [PATCH v2 00/25] mm: introduce numa_memblks

On Wed, Jul 24, 2024 at 10:48:42PM -0400, Zi Yan wrote:
> On 24 Jul 2024, at 20:35, Zi Yan wrote:
> > On 24 Jul 2024, at 18:44, Zi Yan wrote:
> >>
> >> Hi,
> >>
> >> I have tested this series on both x86_64 and arm64. It works fine on x86_64.
> >> All numa=fake= options work as they did before the series.
> >>
> >> But I am not able to boot the kernel (no printout at all) on arm64 VM
> >> (Mac mini M1 VMWare). By git bisecting, arch_numa: switch over to numa_memblks
> >> is the first patch causing the boot failure. I see the warning:
> >>
> >> WARNING: modpost: vmlinux: section mismatch in reference: numa_add_cpu+0x1c (section: .text) -> early_cpu_to_node (section: .init.text)
> >>
> >> I am not sure if it is red herring or not, since changing early_cpu_to_node
> >> to cpu_to_node in numa_add_cpu() from mm/numa_emulation.c did get rid of the
> >> warning, but the system still failed to boot.
> >>
> >> Please note that you need binutils 2.40 to build the arm64 kernel, since there
> >> is a bug(https://sourceware.org/bugzilla/show_bug.cgi?id=31924) in 2.42 preventing
> >> arm64 kernel from booting as well.
> >>
> >> My config is attached.
> >
> > I get more info after adding earlycon to the boot option.
> > pgdat is NULL, causing issues when free_area_init_node() is dereferencing
> > it at first WARN_ON.
> >
> > FYI, my build is this series on top of v6.10 instead of the base commit,
> > where the series applies cleanly on top v6.10.
> 
> OK, the issue comes from that my arm64 VM has no ACPI but x86_64 VM has it,
> thus on arm64 VM numa_init(arch_acpi_numa_ini) failed in arch_numa_init()
> and the code falls back to numa_init(dummy_numa_init). In dummy_numa_init(),
> before patch 23 "arch_numa: switch over to numa_memblks", numa_add_memblk()
> from drivers/base/arch_numa.c is called on arm64, which unconditionally
> set 0 to numa_nodes_parsed. This is missing in the x86 version of
> numa_add_memblk(), which is now used by all arch. By adding the patch
> below, my arm64 kernel boots in the VM.
> 
> 
> diff --git a/drivers/base/arch_numa.c b/drivers/base/arch_numa.c
> index 806550239d08..354f15b8d9b7 100644
> --- a/drivers/base/arch_numa.c
> +++ b/drivers/base/arch_numa.c
> @@ -279,6 +279,7 @@ static int __init dummy_numa_init(void)
>                 pr_err("NUMA init failed\n");
>                 return ret;
>         }
> +       node_set(0, numa_nodes_parsed);
> 
>         numa_off = true;
>         return 0;
> 
> 
> Feel free to add
> 
> Tested-by: Zi Yan <[email protected]> # for x86_64 and arm64
> 
> after you incorporate the fix.

Thanks a lot for testing, debugging and fixing! 
> 
> --
> Best Regards,
> Yan, Zi



-- 
Sincerely yours,
Mike.