Re: [RFC PATCH 2/4] x86/setup: parse acpi to get hotplug info before init_mem_mapping()

From: Dave Hansen
Date: Mon Jan 07 2019 - 12:11:44 EST



On 1/7/19 12:24 AM, Pingfan Liu wrote:
> At present, memblock bottom-up allocation can help us against stamping over
> movable node in very high probability.

Is this what you are fixing? Making a "high probability", a certainty?
Is this the problem?

> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index acbcd62..df4132c 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -805,6 +805,20 @@ dump_kernel_offset(struct notifier_block *self, unsigned long v, void *p)
> return 0;
> }
>
> +/* only need the effect of acpi_numa_memory_affinity_init()
> + * ->memblock_mark_hotplug()
> + */

CodingStyle, please.

> +static int early_detect_acpi_memhotplug(void)
> +{
> +#ifdef CONFIG_ACPI_NUMA
> + acpi_table_upgrade(__va(get_ramdisk_image()), get_ramdisk_size());

This adds a new, early, call to acpi_table_upgrade(), and presumably all
the following functions. However, it does not remove any of the later
calls. How do they interact with each other now that they are
presumably called twice?

> + acpi_table_init();
> + acpi_numa_init();
> + acpi_tb_terminate();
> +#endif
> + return 0;
> +}

Why does this return an 'int' that is unconsumed by its lone caller?

There seems to be a lack of comments on this newly-added code.

> /*
> * Determine if we were loaded by an EFI loader. If so, then we have also been
> * passed the efi memmap, systab, etc., so we should use these data structures
> @@ -1131,6 +1145,7 @@ void __init setup_arch(char **cmdline_p)
> trim_platform_memory_ranges();
> trim_low_memory_range();
>
> + early_detect_acpi_memhotplug();

Comments, please. Why is this call here, specifically? What is it doing?