Ok. Thanks.

Acked-by: Yasunori Goto <y-goto@jp.fujitsu.com>


quoted text
> Generic helper function to remove section mappings and sysfs entries
> for the section of the memory we are removing.  offline_pages() correctly 
> adjusted zone and marked the pages reserved.
> 
> TODO: Yasunori Goto is working on patches to freeup allocations from bootmem.
> 
> Signed-off-by: Badari Pulavarty <pbadari@us.ibm.com>
> 
> ---
>  include/linux/memory_hotplug.h |    6 +++-
>  mm/memory_hotplug.c            |   55 +++++++++++++++++++++++++++++++++++++++++
>  mm/sparse.c                    |   45 +++++++++++++++++++++++++++++++--
>  3 files changed, 102 insertions(+), 4 deletions(-)
> 
> Index: linux-2.6.25-rc5/mm/memory_hotplug.c
> ===================================================================
> --- linux-2.6.25-rc5.orig/mm/memory_hotplug.c	2008-03-21 07:00:37.000000000 -0800
> +++ linux-2.6.25-rc5/mm/memory_hotplug.c	2008-03-25 15:03:58.000000000 -0800
> @@ -102,6 +102,25 @@ static int __add_section(struct zone *zo
>  	return register_new_memory(__pfn_to_section(phys_start_pfn));
>  }
>  
> +static int __remove_section(struct zone *zone, struct mem_section *ms)
> +{
> +	unsigned long flags;
> +	struct pglist_data *pgdat = zone->zone_pgdat;
> +	int ret = -EINVAL;
> +
> +	if (!valid_section(ms))
> +		return ret;
> +
> +	ret = unregister_memory_section(ms);
> +	if (ret)
> +		return ret;
> +
> +	pgdat_resize_lock(pgdat, &flags);
> +	sparse_remove_one_section(zone, ms);
> +	pgdat_resize_unlock(pgdat, &flags);
> +	return 0;
> +}
> +
>  /*
>   * Reasonably generic function for adding memory.  It is
>   * expected that archs that support memory hotplug will
> @@ -135,6 +154,42 @@ int __add_pages(struct zone *zone, unsig
>  }
>  EXPORT_SYMBOL_GPL(__add_pages);
>  
> +/**
> + * __remove_pages() - remove sections of pages from a zone
> + * @zone: zone from which pages need to be removed
> + * @phys_start_pfn: starting pageframe (must be aligned to start of a section)
> + * @nr_pages: number of pages to remove (must be multiple of section size)
> + *
> + * Generic helper function to remove section mappings and sysfs entries
> + * for the section of the memory we are removing. Caller needs to make
> + * sure that pages are marked reserved and zones are adjust properly by
> + * calling offline_pages().
> + */
> +int __remove_pages(struct zone *zone, unsigned long phys_start_pfn,
> +		 unsigned long nr_pages)
> +{
> +	unsigned long i, ret = 0;
> +	int sections_to_remove;
> +
> +	/*
> +	 * We can only remove entire sections
> +	 */
> +	BUG_ON(phys_start_pfn & ~PAGE_SECTION_MASK);
> +	BUG_ON(nr_pages % PAGES_PER_SECTION);
> +
> +	release_mem_region(phys_start_pfn << PAGE_SHIFT, nr_pages * PAGE_SIZE);
> +
> +	sections_to_remove = nr_pages / PAGES_PER_SECTION;
> +	for (i = 0; i < sections_to_remove; i++) {
> +		unsigned long pfn = phys_start_pfn + i*PAGES_PER_SECTION;
> +		ret = __remove_section(zone, __pfn_to_section(pfn));
> +		if (ret)
> +			break;
> +	}
> +	return ret;
> +}
> +EXPORT_SYMBOL_GPL(__remove_pages);
> +
>  static void grow_zone_span(struct zone *zone,
>  		unsigned long start_pfn, unsigned long end_pfn)
>  {
> Index: linux-2.6.25-rc5/mm/sparse.c
> ===================================================================
> --- linux-2.6.25-rc5.orig/mm/sparse.c	2008-03-21 07:00:37.000000000 -0800
> +++ linux-2.6.25-rc5/mm/sparse.c	2008-03-25 13:59:51.000000000 -0800
> @@ -198,12 +198,13 @@ static unsigned long sparse_encode_mem_m
>  }
>  
>  /*
> - * We need this if we ever free the mem_maps.  While not implemented yet,
> - * this function is included for parity with its sibling.
> + * Decode mem_map from the coded memmap
>   */
> -static __attribute((unused))
> +static
>  struct page *sparse_decode_mem_map(unsigned long coded_mem_map, unsigned long pnum)
>  {
> +	/* mask off the extra low bits of information */
> +	coded_mem_map &= SECTION_MAP_MASK;
>  	return ((struct page *)coded_mem_map) + section_nr_to_pfn(pnum);
>  }
>  
> @@ -363,6 +364,28 @@ static void __kfree_section_memmap(struc
>  }
>  #endif /* CONFIG_SPARSEMEM_VMEMMAP */
>  
> +static void free_section_usemap(struct page *memmap, unsigned long *usemap)
> +{
> +	if (!usemap)
> +		return;
> +
> +	/*
> +	 * Check to see if allocation came from hot-plug-add
> +	 */
> +	if (PageSlab(virt_to_page(usemap))) {
> +		kfree(usemap);
> +		if (memmap)
> +			__kfree_section_memmap(memmap, PAGES_PER_SECTION);
> +		return;
> +	}
> +
> +	/*
> +	 * TODO: Allocations came from bootmem - how do I free up ?
> +	 */
> +	printk(KERN_WARNING "Not freeing up allocations from bootmem "
> +			"- leaking memory\n");
> +}
> +
>  /*
>   * returns the number of sections whose mem_maps were properly
>   * set.  If this is <=0, then that means that the passed-in
> @@ -415,4 +438,20 @@ out:
>  	}
>  	return ret;
>  }
> +
> +void sparse_remove_one_section(struct zone *zone, struct mem_section *ms)
> +{
> +	struct page *memmap = NULL;
> +	unsigned long *usemap = NULL;
> +
> +	if (ms->section_mem_map) {
> +		usemap = ms->pageblock_flags;
> +		memmap = sparse_decode_mem_map(ms->section_mem_map,
> +						__section_nr(ms));
> +		ms->section_mem_map = 0;
> +		ms->pageblock_flags = NULL;
> +	}
> +
> +	free_section_usemap(memmap, usemap);
> +}
>  #endif
> Index: linux-2.6.25-rc5/include/linux/memory_hotplug.h
> ===================================================================
> --- linux-2.6.25-rc5.orig/include/linux/memory_hotplug.h	2008-03-21 07:00:36.000000000 -0800
> +++ linux-2.6.25-rc5/include/linux/memory_hotplug.h	2008-03-25 13:59:51.000000000 -0800
> @@ -8,6 +8,7 @@
>  struct page;
>  struct zone;
>  struct pglist_data;
> +struct mem_section;
>  
>  #ifdef CONFIG_MEMORY_HOTPLUG
>  /*
> @@ -64,9 +65,11 @@ extern int offline_pages(unsigned long, 
>  /* reasonably generic interface to expand the physical pages in a zone  */
>  extern int __add_pages(struct zone *zone, unsigned long start_pfn,
>  	unsigned long nr_pages);
> +extern int __remove_pages(struct zone *zone, unsigned long start_pfn,
> +	unsigned long nr_pages);
>  
>  /*
> - * Walk thorugh all memory which is registered as resource.
> + * Walk through all memory which is registered as resource.
>   * arg is (start_pfn, nr_pages, private_arg_pointer)
>   */
>  extern int walk_memory_resource(unsigned long start_pfn,
> @@ -188,5 +191,6 @@ extern int arch_add_memory(int nid, u64 
>  extern int remove_memory(u64 start, u64 size);
>  extern int sparse_add_one_section(struct zone *zone, unsigned long start_pfn,
>  								int nr_pages);
> +extern void sparse_remove_one_section(struct zone *zone, struct mem_section *ms);
>  
>  #endif /* __LINUX_MEMORY_HOTPLUG_H */
> 
> 

-- 
Yasunori Goto 


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