Subject: Re: [PATCH 16/21] mm: remove early_pfn_in_nid() and CONFIG_NODES_SPAN_OTHER_NODES

From: Baoquan He <[email-masked]>
Date: Thu, 23 Apr 2020 09:13:12 +0800

On 04/12/20 at 10:48pm, Mike Rapoport wrote:
> From: Mike Rapoport <[email-masked]>
> 
> The commit f47ac088c406 ("mm: memmap_init: iterate over memblock regions

This commit id should be a temporary one, will be changed when merged
into maintainer's tree and linus's tree. Only saying last patch plus the
patch subject is OK?

> rather that check each PFN") made early_pfn_in_nid() obsolete and since
> CONFIG_NODES_SPAN_OTHER_NODES is only used to pick a stub or a real
> implementation of early_pfn_in_nid() it is also not needed anymore.
> 
> Remove both early_pfn_in_nid() and the CONFIG_NODES_SPAN_OTHER_NODES.
> 
> Co-developed-by: Hoan Tran <[email-masked]>
> Signed-off-by: Hoan Tran <[email-masked]>
> Signed-off-by: Mike Rapoport <[email-masked]>
> ---
>  arch/powerpc/Kconfig |  9 ---------
>  arch/sparc/Kconfig   |  9 ---------
>  arch/x86/Kconfig     |  9 ---------
>  mm/page_alloc.c      | 20 --------------------
>  4 files changed, 47 deletions(-)
> 
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index 5f86b22b7d2c..74f316deeae1 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -685,15 +685,6 @@ config ARCH_MEMORY_PROBE
>  	def_bool y
>  	depends on MEMORY_HOTPLUG
>  
> -# Some NUMA nodes have memory ranges that span
> -# other nodes.  Even though a pfn is valid and
> -# between a node's start and end pfns, it may not
> -# reside on that node.  See memmap_init_zone()
> -# for details.
> -config NODES_SPAN_OTHER_NODES
> -	def_bool y
> -	depends on NEED_MULTIPLE_NODES
> -
>  config STDBINUTILS
>  	bool "Using standard binutils settings"
>  	depends on 44x
> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
> index 795206b7b552..0e4f3891b904 100644
> --- a/arch/sparc/Kconfig
> +++ b/arch/sparc/Kconfig
> @@ -286,15 +286,6 @@ config NODES_SHIFT
>  	  Specify the maximum number of NUMA Nodes available on the target
>  	  system.  Increases memory reserved to accommodate various tables.
>  
> -# Some NUMA nodes have memory ranges that span
> -# other nodes.  Even though a pfn is valid and
> -# between a node's start and end pfns, it may not
> -# reside on that node.  See memmap_init_zone()
> -# for details.
> -config NODES_SPAN_OTHER_NODES
> -	def_bool y
> -	depends on NEED_MULTIPLE_NODES
> -
>  config ARCH_SPARSEMEM_ENABLE
>  	def_bool y if SPARC64
>  	select SPARSEMEM_VMEMMAP_ENABLE
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 9d3e95b4fb85..37dac095659e 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -1581,15 +1581,6 @@ config X86_64_ACPI_NUMA
>  	---help---
>  	  Enable ACPI SRAT based node topology detection.
>  
> -# Some NUMA nodes have memory ranges that span
> -# other nodes.  Even though a pfn is valid and
> -# between a node's start and end pfns, it may not
> -# reside on that node.  See memmap_init_zone()
> -# for details.
> -config NODES_SPAN_OTHER_NODES
> -	def_bool y
> -	depends on X86_64_ACPI_NUMA
> -
>  config NUMA_EMU
>  	bool "NUMA emulation"
>  	depends on NUMA
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index c43ce8709457..343d87b8697d 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1541,26 +1541,6 @@ int __meminit early_pfn_to_nid(unsigned long pfn)
>  }
>  #endif /* CONFIG_NEED_MULTIPLE_NODES */
>  
> -#ifdef CONFIG_NODES_SPAN_OTHER_NODES
> -/* Only safe to use early in boot when initialisation is single-threaded */
> -static inline bool __meminit early_pfn_in_nid(unsigned long pfn, int node)
> -{
> -	int nid;
> -
> -	nid = __early_pfn_to_nid(pfn, &early_pfnnid_cache);
> -	if (nid >= 0 && nid != node)
> -		return false;
> -	return true;
> -}
> -
> -#else
> -static inline bool __meminit early_pfn_in_nid(unsigned long pfn, int node)
> -{
> -	return true;
> -}
> -#endif

And macro early_pfn_valid() is not needed either, we may need remove it
too. 

Otherwise, removing NODES_SPAN_OTHER_NODES in this patch looks good.

Reviewed-by: Baoquan He <[email-masked]>

> -
> -
>  void __init memblock_free_pages(struct page *page, unsigned long pfn,
>  							unsigned int order)
>  {
> -- 
> 2.25.1
>