linux-kernel - Re: [PATCH v7 08/12] mm/sparsemem: Prepare for sub-section ranges

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Message-ID: <20190503110019.GG15740@linux>
Date:   Fri, 3 May 2019 13:00:19 +0200
From:   Oscar Salvador <osalvador@...e.de>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     akpm@...ux-foundation.org, Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Logan Gunthorpe <logang@...tatee.com>,
        linux-nvdimm@...ts.01.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v7 08/12] mm/sparsemem: Prepare for sub-section ranges

On Wed, May 01, 2019 at 10:56:05PM -0700, Dan Williams wrote:
> Prepare the memory hot-{add,remove} paths for handling sub-section
> ranges by plumbing the starting page frame and number of pages being
> handled through arch_{add,remove}_memory() to
> sparse_{add,remove}_one_section().
> 
> This is simply plumbing, small cleanups, and some identifier renames. No
> intended functional changes.
> 
> Cc: Michal Hocko <mhocko@...e.com>
> Cc: Vlastimil Babka <vbabka@...e.cz>
> Cc: Logan Gunthorpe <logang@...tatee.com>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>
> ---
>  include/linux/memory_hotplug.h |    7 +-
>  mm/memory_hotplug.c            |  118 +++++++++++++++++++++++++---------------
>  mm/sparse.c                    |    7 +-
>  3 files changed, 83 insertions(+), 49 deletions(-)
> 
> diff --git a/include/linux/memory_hotplug.h b/include/linux/memory_hotplug.h
> index ae892eef8b82..835a94650ee3 100644
> --- a/include/linux/memory_hotplug.h
> +++ b/include/linux/memory_hotplug.h
> @@ -354,9 +354,10 @@ extern int add_memory_resource(int nid, struct resource *resource);
>  extern void move_pfn_range_to_zone(struct zone *zone, unsigned long start_pfn,
>  		unsigned long nr_pages, struct vmem_altmap *altmap);
>  extern bool is_memblock_offlined(struct memory_block *mem);
> -extern int sparse_add_one_section(int nid, unsigned long start_pfn,
> -				  struct vmem_altmap *altmap);
> -extern void sparse_remove_one_section(struct zone *zone, struct mem_section *ms,
> +extern int sparse_add_section(int nid, unsigned long pfn,
> +		unsigned long nr_pages, struct vmem_altmap *altmap);
> +extern void sparse_remove_section(struct zone *zone, struct mem_section *ms,
> +		unsigned long pfn, unsigned long nr_pages,
>  		unsigned long map_offset, struct vmem_altmap *altmap);
>  extern struct page *sparse_decode_mem_map(unsigned long coded_mem_map,
>  					  unsigned long pnum);
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 108380e20d8f..9f73332af910 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -251,22 +251,44 @@ void __init register_page_bootmem_info_node(struct pglist_data *pgdat)
>  }
>  #endif /* CONFIG_HAVE_BOOTMEM_INFO_NODE */
>  
> -static int __meminit __add_section(int nid, unsigned long phys_start_pfn,
> -		struct vmem_altmap *altmap, bool want_memblock)
> +static int __meminit __add_section(int nid, unsigned long pfn,
> +		unsigned long nr_pages,	struct vmem_altmap *altmap,
> +		bool want_memblock)
>  {
>  	int ret;
>  
> -	if (pfn_valid(phys_start_pfn))
> +	if (pfn_valid(pfn))
>  		return -EEXIST;
>  
> -	ret = sparse_add_one_section(nid, phys_start_pfn, altmap);
> +	ret = sparse_add_section(nid, pfn, nr_pages, altmap);
>  	if (ret < 0)
>  		return ret;
>  
>  	if (!want_memblock)
>  		return 0;
>  
> -	return hotplug_memory_register(nid, __pfn_to_section(phys_start_pfn));
> +	return hotplug_memory_register(nid, __pfn_to_section(pfn));
> +}
> +
> +static int subsection_check(unsigned long pfn, unsigned long nr_pages,
> +		unsigned long flags, const char *reason)
> +{
> +	/*
> +	 * Only allow partial section hotplug for !memblock ranges,
> +	 * since register_new_memory() requires section alignment, and

What is register_new_memory?

Reviewed-by: Oscar Salvador <osalvador@...e.de>

-- 
Oscar Salvador
SUSE L3